[PATCH v14 00/24] Allow AET to use PMT as loadable module

[PATCH v14 00/24] Allow AET to use PMT as loadable module

[Tony Luck]

Requiring INTEL_PMT_TELEMETRY=y to enable AET is a functional workaround
to enable enumeration of Application Energy Telemetry (AET) events, but
unacceptable to many users. It results in increased configuration complexity,
increased kernel memory footprint and inability to patch problems by unloading
a module and loading an updated version.

Add a registration function to the AET code that can be used by
INTEL_PMT_TELEMETRY to provide the enumeration functions.

INTEL_PMT_TELEMETRY can be loaded/unloaded independently of
resctrl file system mount/unmount. Perform enumeration on
every mount and cleanup on every unmount.

Patch series based on TIP tree x86/cache branch current HEAD is:
  2c10b3fa5bdf ("fs/resctrl: Ensure default group reports tasks on monitor-only systems")

Signed-off-by: Tony Luck <tony.luck@intel.com>

Previous version (v13) here:
Link: https://lore.kernel.org/all/20260928221509.68002-1-tony.luck@intel.com/

Changes since v13:

[PATCH v14 01/24] x86/cpufeatures: Add missing CQM feature dependency
	Add AMD64 manual
	s/Linux X86_FEATURE_CQM/X86_FEATURE_CQM/
	Complete the trio of context, problem, solution paragraphs
	by adding the problem statement.

[PATCH v14 02/24] x86/resctrl: Check if monitoring features are supported

	Move maintainer note after the "---"
	Put the X86_FEATURE_* parenthetical comments back (without "Linux")
	s/monitoring features/resource monitoring features/g
	Add Reinette RB tag
	Add problem paragraph between context and solution.
	Add Chen Yu Tested-by tag

[PATCH v14 03/24] x86/resctrl: Centralize monitoring feature enumeration
	Structure commit in context, problem, solution.
	Add note that there is still one user of boot_cpu_data.

[PATCH v14 04/24] x86/resctrl: Apply Intel MBM quirk from rdt_get_l3_mon_config()
	Replaced commit message with Reinette suggestion from v12 review.
	Two tweaks suggested by AI commit review:
		Be more specific that "early" enumeration is simply
		before resctrl.
		s/consumer/reader/g

[PATCH v14 05/24] x86/resctrl: Delete resctrl_cpu_detect()
	Split first paragraph into two: context and problem.
	Don't list all the fields as a regex.

[PATCH v14 06/24] arm,x86,fs/resctrl: Replace architecture capability helpers with generic versions
	New Subject: without {alloc,mon}
	New commit message in context, problem, solution format
	Did not apply Reinette RB tag because of commit message rewrite.

[PATCH v14 07/24] x86/resctrl: Update special case for Intel Haswell enumeration
	Updated commit comment in context, problem, solution form.

[PATCH v14 08/24] x86/resctrl: Delete rdt_alloc_capable and rdt_mon_capable
	New commit message in context, problem, solution format.

[PATCH v14 09/24] fs/resctrl: Remove redundant calls to resctrl_mon_capable()
	New commit message confessing that this is fixing a performance
	problem created by an earlier patch this series.

[PATCH v14 10/24] x86/resctrl: Honor rdt={perf|energy} options to force enable AET events
	New commit message. Dropped previous supplied Reinette RB tag.

[PATCH v14 11/24] fs/resctrl: Add interface to disable a monitor event
	New commit message. Dropped previous applied Reinette RB tag.

[PATCH v14 12/24] arm,x86,fs/resctrl: Allocate maximum needed rmid_ptrs[]
	New commit message.

[PATCH v14 13/24] arm,x86,fs/resctrl: Use right size for L3 monitor data structures
	New commit message.

[PATCH v14 14/24] x86,fs/resctrl: Handle systems where AET is the only monitoring feature
	New commit message.

[PATCH v14 15/24] x86/resctrl: Add PMT registration API for AET enumeration callbacks
	New commit message.

[PATCH v14 16/24] platform/x86/intel/pmt: Register enumeration functions with resctrl
	New commit message.

[PATCH v14 17/24] x86/resctrl: Use registered function pointers for AET enumeration
	Updates to resolve locking problems reported by Sashiko in v13.

	AET is now going to use a single mutex for both registration
	and in a later patch for device removal. So change the name
	from aet_register_lock to just aet_lock.

	Reverse locking hierarchy between AET and pmt_telemetry.
	No longer OK to call into pmt_telemetry to enumerate
	features with the aet_lock held. Instead, make use of
	module pinning while holding aet_lock.

	New commit message

[PATCH v14 18/24] arm,x86,fs/resctrl: Enumerate AET on every resctrl mount
	New commit comment.
	aet_register_lock name changed to aet_lock.
	Babu: Add commit comment about event_group::force_off

[PATCH v14 19/24] x86/resctrl: Enforce system RMID limit on AET
	New commit comment

[PATCH v14 20/24] x86/resctrl: Export interface to report telemetry unbind/remove
	Dropped aet_mmio_lock. Now safe to use aet_lock.
	New commit message
	Add code comment noting that per-package may be over-reaction.

[PATCH v14 21/24] platform/x86/intel/pmt: Inform resctrl when MMIO maps are being removed
	Added commit comment on lock order.
	New commit comment.

[PATCH v14 22/24] x86/resctrl: Require 64-bit x86 for resctrl support
	New commit message.

[PATCH v14 23/24] x86/resctrl: Simplify Kconfig options for resctrl
	New commit message.

[PATCH v14 24/24] x86,fs/resctrl: Document telemetry mount timing caveat
	Updated commit message. Include unmount/remount as solution
	if early mount did not include AET.


Tony Luck (24):
  x86/cpufeatures: Add missing CQM feature dependency
  x86/resctrl: Check if monitoring features are supported
  x86/resctrl: Centralize monitoring feature enumeration
  x86/resctrl: Apply Intel MBM quirk from rdt_get_l3_mon_config()
  x86/resctrl: Delete resctrl_cpu_detect()
  arm,x86,fs/resctrl: Replace architecture capability helpers with
    generic versions
  x86/resctrl: Update special case for Intel Haswell enumeration
  x86/resctrl: Delete rdt_alloc_capable and rdt_mon_capable
  fs/resctrl: Remove redundant calls to resctrl_mon_capable()
  x86/resctrl: Honor rdt={perf|energy} options to force enable AET
    events
  fs/resctrl: Add interface to disable a monitor event
  arm,x86,fs/resctrl: Allocate maximum needed rmid_ptrs[]
  arm,x86,fs/resctrl: Use right size for L3 monitor data structures
  x86,fs/resctrl: Handle systems where AET is the only monitoring
    feature
  x86/resctrl: Add PMT registration API for AET enumeration callbacks
  platform/x86/intel/pmt: Register enumeration functions with resctrl
  x86/resctrl: Use registered function pointers for AET enumeration
  arm,x86,fs/resctrl: Enumerate AET on every resctrl mount
  x86/resctrl: Enforce system RMID limit on AET
  x86/resctrl: Export interface to report telemetry unbind/remove
  platform/x86/intel/pmt: Inform resctrl when MMIO maps are being
    removed
  x86/resctrl: Require 64-bit x86 for resctrl support
  x86/resctrl: Simplify Kconfig options for resctrl
  x86,fs/resctrl: Document telemetry mount timing caveat

 Documentation/filesystems/resctrl.rst      |   8 +-
 include/linux/arm_mpam.h                   |   3 -
 include/linux/intel_vsec.h                 |  14 ++
 include/linux/resctrl.h                    |  84 ++++++++++-
 arch/x86/include/asm/processor.h           |   4 -
 arch/x86/include/asm/resctrl.h             |  24 +---
 arch/x86/kernel/cpu/resctrl/internal.h     |  33 ++---
 arch/x86/kernel/cpu/amd.c                  |   3 -
 arch/x86/kernel/cpu/cpuid-deps.c           |   1 +
 arch/x86/kernel/cpu/hygon.c                |   3 -
 arch/x86/kernel/cpu/intel.c                |   7 -
 arch/x86/kernel/cpu/resctrl/core.c         | 150 +++++++++++---------
 arch/x86/kernel/cpu/resctrl/intel_aet.c    | 156 +++++++++++++++++++--
 arch/x86/kernel/cpu/resctrl/monitor.c      |  78 +++++++----
 drivers/platform/x86/intel/pmt/telemetry.c |  45 +++++-
 drivers/resctrl/mpam_resctrl.c             |  44 +++---
 fs/resctrl/monitor.c                       | 111 +++++++++++----
 fs/resctrl/pseudo_lock.c                   |   6 +-
 fs/resctrl/rdtgroup.c                      |  72 ++++++----
 arch/x86/Kconfig                           |  15 +-
 arch/x86/kernel/cpu/resctrl/Makefile       |   3 +-
 21 files changed, 590 insertions(+), 274 deletions(-)


base-commit: 2c10b3fa5bdf61e344bc522e6c2e00d870ce7ab8
-- 
2.56.0

[PATCH v14 01/24] x86/cpufeatures: Add missing CQM feature dependency

[Tony Luck]

The L3 monitoring features are enumerated from CPUID leaf 0xF. Both the Intel
Software Developer's Manual, and the AMD64 Architecture Programmer's Manual,
say that software must check that CPUID(0x7,0x0).EBX[12] (X86_FEATURE_CQM)
is set before checking for monitoring features in CPUID leaf 0xF.

The CPU feature dependency table does not record this requirement.

Add the missing dependency of X86_FEATURE_CQM_LLC on X86_FEATURE_CQM.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
---
v14:
	Add AMD64 manual
	s/Linux X86_FEATURE_CQM/X86_FEATURE_CQM/
	Complete the trio of context, problem, solution paragraphs
	by adding the problem statement.
---
 arch/x86/kernel/cpu/cpuid-deps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 99801e844b30..93d45b688f6c 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -67,6 +67,7 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_AVX512_4FMAPS,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512_VPOPCNTDQ,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512_VP2INTERSECT,	X86_FEATURE_AVX512VL  },
+	{ X86_FEATURE_CQM_LLC,			X86_FEATURE_CQM       },
 	{ X86_FEATURE_CQM_OCCUP_LLC,		X86_FEATURE_CQM_LLC   },
 	{ X86_FEATURE_CQM_MBM_TOTAL,		X86_FEATURE_CQM_LLC   },
 	{ X86_FEATURE_CQM_MBM_LOCAL,		X86_FEATURE_CQM_LLC   },
-- 
2.56.0

[PATCH v14 02/24] x86/resctrl: Check if monitoring features are supported

[Tony Luck]

Both Intel and AMD manuals say that software must first check
CPUID(0x7,0x0).EBX[12] (X86_FEATURE_CQM) to see if any resource monitoring
features are supported before checking for resource specific features
supported in subleaves. The L3 resource monitoring features are further gated
by CPUID(0xF,0x0).EDX[1] (X86_FEATURE_CQM_LLC).

resctrl enables L3 monitoring based only on the individual monitoring
features. It can thus enable L3 monitoring on a system that does not report
support for resource monitoring.

Do not enable L3 monitoring unless both X86_FEATURE_CQM and X86_FEATURE_CQM_LLC
are supported. This also applies to assignable counters, which rely on the
RMID count and scale enumerated in CPUID leaf 0xF.

Fixes: cbc82b172638 ("x86: Add support for Intel Cache QoS Monitoring (CQM) detection")
Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Tested-by: Chen Yu <yu.c.chen@intel.com>
---
v14:
Maintainer note: No need to backport this fix. No issues have been seen
from this failure to follow the exact enumeration process in the manual.

	Move maintainer note after the "---"
	Put the X86_FEATURE_* parenthetical comments back (without "Linux")
	s/monitoring features/resource monitoring features/g
	Add Reinette RB tag
	Add problem paragraph between context and solution.
	Add Chen Yu Tested-by tag
---
 arch/x86/kernel/cpu/resctrl/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 55214d6fdc49..34ca3c7cc046 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -968,6 +968,14 @@ static __init bool get_rdt_mon_resources(void)
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
 	bool ret = false;
 
+	/* Any monitoring at all? */
+	if (!cpu_feature_enabled(X86_FEATURE_CQM))
+		return false;
+
+	/* Any of the L3 monitoring features? */
+	if (!cpu_feature_enabled(X86_FEATURE_CQM_LLC))
+		return false;
+
 	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
 		resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL);
 		ret = true;
-- 
2.56.0

[PATCH v14 03/24] x86/resctrl: Centralize monitoring feature enumeration

[Tony Luck]

The original "perf" implementation of Intel Cache QoS Monitoring (CQM)
put parameters from CPUID into fields of the cpuinfo_x86 structure. The
perf implementation was reverted and replaced by resctrl. The enumerated
parameters remained in the boot_cpu_data structure.

resctrl is the only consumer of these values, yet it depends on generic
x86 CPU setup to enumerate them.

Centralize all L3 monitoring enumeration within resctrl in preparation for
removal of resctrl fields from struct cpuinfo_x86. The Intel MBM correction
factor quirk remains the only reader of the cached values.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Structure commit in context, problem, solution.
	Add note that there is still one user of boot_cpu_data.
---
 arch/x86/include/asm/resctrl.h        |  9 ++++----
 arch/x86/kernel/cpu/resctrl/monitor.c | 32 ++++++++++++++++++++++++---
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 8f6edcdcfd87..c9f9db96f792 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -44,6 +44,7 @@ DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
 
 extern bool rdt_alloc_capable;
 extern bool rdt_mon_capable;
+extern unsigned int rdt_l3_mon_scale;
 
 DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
@@ -132,11 +133,9 @@ static inline void __resctrl_sched_in(struct task_struct *tsk)
 
 static inline unsigned int resctrl_arch_round_mon_val(unsigned int val)
 {
-	unsigned int scale = boot_cpu_data.x86_cache_occ_scale;
-
-	/* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */
-	val /= scale;
-	return val * scale;
+	/* Round down to nearest h/w monitoring unit */
+	val /= rdt_l3_mon_scale;
+	return val * rdt_l3_mon_scale;
 }
 
 static inline void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid,
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 3838e0a13d36..89b83cc7e800 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -32,6 +32,11 @@
  */
 bool rdt_mon_capable;
 
+/*
+ * Scale factor to convert L3 monitor events to bytes.
+ */
+unsigned int __ro_after_init rdt_l3_mon_scale;
+
 #define CF(cf)	((unsigned long)(1048576 * (cf) + 0.5))
 
 static int snc_nodes_per_l3_cache = 1;
@@ -418,16 +423,37 @@ static __init int snc_get_config(void)
 
 int __init rdt_get_l3_mon_config(struct rdt_resource *r)
 {
-	unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+	unsigned int mbm_offset;
 	unsigned int threshold;
 	u32 eax, ebx, ecx, edx;
+	u32 num_rmid;
+
+	/* Resource monitoring leaf is 0xf. L3 monitoring details in subleaf 1 */
+	cpuid_count(0xf, 1, &eax, &ebx, &ecx, &edx);
+	mbm_offset = eax & GENMASK(7, 0);
+	rdt_l3_mon_scale = ebx;
+	num_rmid = ecx + 1;
+
+	if (!mbm_offset) {
+		switch (boot_cpu_data.x86_vendor) {
+		case X86_VENDOR_AMD:
+			mbm_offset = MBM_CNTR_WIDTH_OFFSET_AMD;
+			break;
+		case X86_VENDOR_HYGON:
+			mbm_offset = MBM_CNTR_WIDTH_OFFSET_HYGON;
+			break;
+		default:
+			/* Leave mbm_offset as 0 */
+			break;
+		}
+	}
 
 	snc_nodes_per_l3_cache = snc_get_config();
 
 	resctrl_rmid_realloc_limit = boot_cpu_data.x86_cache_size * 1024;
-	hw_res->mon_scale = boot_cpu_data.x86_cache_occ_scale / snc_nodes_per_l3_cache;
-	r->mon.num_rmid = (boot_cpu_data.x86_cache_max_rmid + 1) / snc_nodes_per_l3_cache;
+	hw_res->mon_scale = rdt_l3_mon_scale / snc_nodes_per_l3_cache;
+	r->mon.num_rmid = num_rmid / snc_nodes_per_l3_cache;
 	hw_res->mbm_width = MBM_CNTR_WIDTH_BASE;
 
 	if (mbm_offset > 0 && mbm_offset <= MBM_CNTR_WIDTH_OFFSET_MAX)
-- 
2.56.0

[PATCH v14 04/24] x86/resctrl: Apply Intel MBM quirk from rdt_get_l3_mon_config()

[Tony Luck]

The Intel MBM correction factor quirk is applied during CPU model checks
that precede resctrl feature enumeration, using the RMID count from
cpuinfo_x86::x86_cache_max_rmid. It is the last reader of the resctrl fields
in struct cpuinfo_x86 now that monitoring feature enumeration is contained
within resctrl.

This lone reader prevents those fields from being removed, and applies
MBM specific setup before resctrl has established that MBM is supported.

Apply the quirk during monitoring feature enumeration in preparation
for removing the resctrl fields from struct cpuinfo_x86.
Keep the decision on whether the quirk is needed with the other model
specific tests to avoid scattering quirk handling.

No functional change intended.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Replaced commit message with Reinette suggestion from v12 review.
	Two tweaks suggested by AI commit review:
		Be more specific that "early" enumeration is simply
		before resctrl.
		s/consumer/reader/g
---
 arch/x86/kernel/cpu/resctrl/internal.h |  4 +--
 arch/x86/kernel/cpu/resctrl/core.c     |  2 +-
 arch/x86/kernel/cpu/resctrl/monitor.c  | 40 ++++++++++++++++----------
 3 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index e3cfa0c10e92..086282a82fca 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -151,6 +151,8 @@ static inline struct rdt_hw_resource *resctrl_to_arch_res(struct rdt_resource *r
 
 extern struct rdt_hw_resource rdt_resources_all[];
 
+extern bool intel_rdt_mbm_need_quirk;
+
 void arch_mon_domain_online(struct rdt_resource *r, struct rdt_l3_mon_domain *d);
 
 /* CPUID.(EAX=10H, ECX=ResID=1).EAX */
@@ -228,8 +230,6 @@ int rdt_get_l3_mon_config(struct rdt_resource *r);
 
 bool rdt_cpu_has(int flag);
 
-void __init intel_rdt_mbm_apply_quirk(void);
-
 void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
 void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r);
 
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 34ca3c7cc046..82b27a0157ae 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1011,7 +1011,7 @@ static __init void __check_quirks_intel(void)
 			set_rdt_options("!l3cat");
 		fallthrough;
 	case INTEL_BROADWELL_X:
-		intel_rdt_mbm_apply_quirk();
+		intel_rdt_mbm_need_quirk = true;
 		break;
 	}
 }
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 89b83cc7e800..468e9821f35a 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -37,6 +37,8 @@ bool rdt_mon_capable;
  */
 unsigned int __ro_after_init rdt_l3_mon_scale;
 
+bool __initdata intel_rdt_mbm_need_quirk;
+
 #define CF(cf)	((unsigned long)(1048576 * (cf) + 0.5))
 
 static int snc_nodes_per_l3_cache = 1;
@@ -51,7 +53,7 @@ static int snc_nodes_per_l3_cache = 1;
  * 1. The threshold 0 is changed to rmid count - 1 so don't do correction
  *    for the case.
  * 2. MBM total and local correction table indexed by core counter which is
- *    equal to (x86_cache_max_rmid + 1) / 8 - 1 and is from 0 up to 27.
+ *    equal to num_rmid / 8 - 1 and is from 0 up to 27.
  * 3. The correction factor is normalized to 2^20 (1048576) so it's faster
  *    to calculate corrected value by shifting:
  *    corrected_value = (original_value * correction_factor) >> 20
@@ -421,6 +423,20 @@ static __init int snc_get_config(void)
 	return ret;
 }
 
+static void __init intel_rdt_mbm_apply_quirk(u32 num_rmid)
+{
+	unsigned int cf_index;
+
+	cf_index = num_rmid / 8 - 1;
+	if (cf_index >= ARRAY_SIZE(mbm_cf_table)) {
+		pr_info("No MBM correction factor available\n");
+		return;
+	}
+
+	mbm_cf_rmidthreshold = mbm_cf_table[cf_index].rmidthreshold;
+	mbm_cf = mbm_cf_table[cf_index].cf;
+}
+
 int __init rdt_get_l3_mon_config(struct rdt_resource *r)
 {
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
@@ -500,25 +516,19 @@ int __init rdt_get_l3_mon_config(struct rdt_resource *r)
 		hw_res->mbm_cntr_assign_enabled = true;
 	}
 
+	/*
+	 * This quirk only applies to Intel Skylake and Broadwell
+	 * CPUs. These don't support Sub-NUMA Cluster. Pass the
+	 * raw number of RMIDs enumerated by CPUID(0xF,0x1).ECX.
+	 */
+	if (intel_rdt_mbm_need_quirk)
+		intel_rdt_mbm_apply_quirk(num_rmid);
+
 	r->mon_capable = true;
 
 	return 0;
 }
 
-void __init intel_rdt_mbm_apply_quirk(void)
-{
-	int cf_index;
-
-	cf_index = (boot_cpu_data.x86_cache_max_rmid + 1) / 8 - 1;
-	if (cf_index >= ARRAY_SIZE(mbm_cf_table)) {
-		pr_info("No MBM correction factor available\n");
-		return;
-	}
-
-	mbm_cf_rmidthreshold = mbm_cf_table[cf_index].rmidthreshold;
-	mbm_cf = mbm_cf_table[cf_index].cf;
-}
-
 static void resctrl_abmc_set_one_amd(void *arg)
 {
 	bool *enable = arg;
-- 
2.56.0

[PATCH v14 05/24] x86/resctrl: Delete resctrl_cpu_detect()

[Tony Luck]

resctrl now enumerates its monitoring properties itself, leaving the resctrl
fields in cpuinfo_x86 without any consumers. These resctrl specific fields
are populated from the vendor CPU identification paths.

This unnecessarily placing resctrl details in generic x86 CPU setup.

Delete the unused fields together with the code that populates them, removing
resctrl from early CPU identification.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
---
v14:
	Split first paragraph into two: context and problem.
	Don't list all the fields as a regex.
---
 arch/x86/include/asm/processor.h   |  4 ---
 arch/x86/include/asm/resctrl.h     |  3 ---
 arch/x86/kernel/cpu/amd.c          |  3 ---
 arch/x86/kernel/cpu/hygon.c        |  3 ---
 arch/x86/kernel/cpu/intel.c        |  7 -----
 arch/x86/kernel/cpu/resctrl/core.c | 42 ------------------------------
 6 files changed, 62 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ec9db0dfa0df..4deb88c61c94 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -185,10 +185,6 @@ struct cpuinfo_x86 {
 	/* in KB - valid for CPUS which support this call: */
 	unsigned int		x86_cache_size;
 	int			x86_cache_alignment;	/* In bytes */
-	/* Cache QoS architectural values, valid only on the BSP: */
-	int			x86_cache_max_rmid;	/* max index */
-	int			x86_cache_occ_scale;	/* scale to bytes */
-	int			x86_cache_mbm_width_offset;
 	int			x86_power;
 	unsigned long		loops_per_jiffy;
 	/* protected processor identification number */
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index c9f9db96f792..2031b30ff25b 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -193,12 +193,9 @@ static inline void resctrl_arch_mon_ctx_free(struct rdt_resource *r,
 					     enum resctrl_event_id evtid,
 					     void *ctx) { }
 
-void resctrl_cpu_detect(struct cpuinfo_x86 *c);
-
 #else
 
 static inline void resctrl_arch_sched_in(struct task_struct *tsk) {}
-static inline void resctrl_cpu_detect(struct cpuinfo_x86 *c) {}
 
 #endif /* CONFIG_X86_CPU_RESCTRL */
 
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 54e14ed276b5..dd82a11084f4 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -23,7 +23,6 @@
 #include <asm/pci-direct.h>
 #include <asm/delay.h>
 #include <asm/debugreg.h>
-#include <asm/resctrl.h>
 #include <asm/msr.h>
 #include <asm/sev.h>
 
@@ -475,8 +474,6 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 		}
 	}
 
-	resctrl_cpu_detect(c);
-
 	/* Figure out Zen generations: */
 	switch (c->x86) {
 	case 0x17:
diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c
index ec51c2b9a257..0f226335dd9a 100644
--- a/arch/x86/kernel/cpu/hygon.c
+++ b/arch/x86/kernel/cpu/hygon.c
@@ -17,7 +17,6 @@
 #include <asm/spec-ctrl.h>
 #include <asm/delay.h>
 #include <asm/msr.h>
-#include <asm/resctrl.h>
 
 #include "cpu.h"
 
@@ -119,8 +118,6 @@ static void bsp_init_hygon(struct cpuinfo_x86 *c)
 			x86_amd_ls_cfg_ssbd_mask = 1ULL << 10;
 		}
 	}
-
-	resctrl_cpu_detect(c);
 }
 
 static void early_init_hygon(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 4297ceb2cb24..2f09710e863c 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -22,7 +22,6 @@
 #include <asm/microcode.h>
 #include <asm/msr.h>
 #include <asm/numa.h>
-#include <asm/resctrl.h>
 #include <asm/thermal.h>
 #include <asm/uaccess.h>
 
@@ -371,11 +370,6 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 		detect_tme_early(c);
 }
 
-static void bsp_init_intel(struct cpuinfo_x86 *c)
-{
-	resctrl_cpu_detect(c);
-}
-
 #ifdef CONFIG_X86_32
 /*
  *	Early probe support logic for ppro memory erratum #50
@@ -804,7 +798,6 @@ static const struct cpu_dev intel_cpu_dev = {
 #endif
 	.c_detect_tlb	= intel_detect_tlb,
 	.c_early_init   = early_init_intel,
-	.c_bsp_init	= bsp_init_intel,
 	.c_init		= init_intel,
 	.c_x86_vendor	= X86_VENDOR_INTEL,
 };
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 82b27a0157ae..f0cfb37482d3 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1083,48 +1083,6 @@ static __init void rdt_init_res_defs(void)
 
 static enum cpuhp_state rdt_online;
 
-/* Runs once on the BSP during boot. */
-void resctrl_cpu_detect(struct cpuinfo_x86 *c)
-{
-	if (!cpu_has(c, X86_FEATURE_CQM_LLC) && !cpu_has(c, X86_FEATURE_ABMC)) {
-		c->x86_cache_max_rmid  = -1;
-		c->x86_cache_occ_scale = -1;
-		c->x86_cache_mbm_width_offset = -1;
-		return;
-	}
-
-	/* will be overridden if occupancy monitoring exists */
-	c->x86_cache_max_rmid = cpuid_ebx(0xf);
-
-	if (cpu_has(c, X86_FEATURE_CQM_OCCUP_LLC) ||
-	    cpu_has(c, X86_FEATURE_CQM_MBM_TOTAL) ||
-	    cpu_has(c, X86_FEATURE_CQM_MBM_LOCAL) ||
-	    cpu_has(c, X86_FEATURE_ABMC)) {
-		u32 eax, ebx, ecx, edx;
-
-		/* QoS sub-leaf, EAX=0Fh, ECX=1 */
-		cpuid_count(0xf, 1, &eax, &ebx, &ecx, &edx);
-
-		c->x86_cache_max_rmid  = ecx;
-		c->x86_cache_occ_scale = ebx;
-		c->x86_cache_mbm_width_offset = eax & 0xff;
-
-		if (!c->x86_cache_mbm_width_offset) {
-			switch (c->x86_vendor) {
-			case X86_VENDOR_AMD:
-				c->x86_cache_mbm_width_offset = MBM_CNTR_WIDTH_OFFSET_AMD;
-				break;
-			case X86_VENDOR_HYGON:
-				c->x86_cache_mbm_width_offset = MBM_CNTR_WIDTH_OFFSET_HYGON;
-				break;
-			default:
-				/* Leave c->x86_cache_mbm_width_offset as 0 */
-				break;
-			}
-		}
-	}
-}
-
 static int __init resctrl_arch_late_init(void)
 {
 	struct rdt_resource *r;
-- 
2.56.0

[PATCH v14 06/24] arm,x86,fs/resctrl: Replace architecture capability helpers with generic versions

[Tony Luck]

resctrl supports allocation or monitoring if any resource is capable of
it. Each architecture answers this via resctrl_arch_alloc_capable() and
resctrl_arch_mon_capable(). x86 maintains global flags for this in
addition to the per-resource flags and must keep both in sync. MPAM
derives the answer from its per-resource flags.

The per-resource flags are part of the resource description that the file
system already has, so the architecture helpers duplicate information
available to the file system.

Define resctrl_alloc_capable() and resctrl_mon_capable() in the file system
based on the per-resource flags and remove the architecture helpers, in
preparation for removing the x86 global flags. The result is unchanged for
MPAM, which presents all monitors on the L3 resource.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New Subject: without {alloc,mon}
	New commit message in context, problem, solution format
	Did not apply Reinette RB tag because of commit message rewrite.
---
 include/linux/arm_mpam.h       |  3 ---
 include/linux/resctrl.h        | 30 ++++++++++++++++++++++++++++
 arch/x86/include/asm/resctrl.h | 10 ----------
 drivers/resctrl/mpam_resctrl.c | 26 ++----------------------
 fs/resctrl/monitor.c           | 10 +++++-----
 fs/resctrl/pseudo_lock.c       |  6 +++---
 fs/resctrl/rdtgroup.c          | 36 +++++++++++++++++-----------------
 7 files changed, 58 insertions(+), 63 deletions(-)

diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h
index f92a36187a52..ba4131048260 100644
--- a/include/linux/arm_mpam.h
+++ b/include/linux/arm_mpam.h
@@ -50,9 +50,6 @@ static inline int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,
 }
 #endif
 
-bool resctrl_arch_alloc_capable(void);
-bool resctrl_arch_mon_capable(void);
-
 void resctrl_arch_set_cpu_default_closid(int cpu, u32 closid);
 void resctrl_arch_set_closid_rmid(struct task_struct *tsk, u32 closid, u32 rmid);
 void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid, u32 rmid);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 10dfdca7f4bf..0e7fce070fde 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -346,6 +346,36 @@ struct rdt_resource {
  */
 struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l);
 
+/*
+ * resctrl_alloc_capable - Are any allocation resources enabled?
+ */
+static inline bool resctrl_alloc_capable(void)
+{
+	struct rdt_resource *r;
+
+	for_each_rdt_resource(r) {
+		if (r->alloc_capable)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * resctrl_mon_capable - Are any monitor resources enabled?
+ */
+static inline bool resctrl_mon_capable(void)
+{
+	struct rdt_resource *r;
+
+	for_each_rdt_resource(r) {
+		if (r->mon_capable)
+			return true;
+	}
+
+	return false;
+}
+
 /**
  * struct resctrl_schema - configuration abilities of a resource presented to
  *			   user-space
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 2031b30ff25b..9c44a7766631 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -50,11 +50,6 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
 
-static inline bool resctrl_arch_alloc_capable(void)
-{
-	return rdt_alloc_capable;
-}
-
 static inline void resctrl_arch_enable_alloc(void)
 {
 	static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
@@ -67,11 +62,6 @@ static inline void resctrl_arch_disable_alloc(void)
 	static_branch_dec_cpuslocked(&rdt_enable_key);
 }
 
-static inline bool resctrl_arch_mon_capable(void)
-{
-	return rdt_mon_capable;
-}
-
 static inline void resctrl_arch_enable_mon(void)
 {
 	static_branch_enable_cpuslocked(&rdt_mon_enable_key);
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index f2c651e9f6ea..7ddee8f5162f 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -75,28 +75,6 @@ static DECLARE_WAIT_QUEUE_HEAD(wait_cacheinfo_ready);
  */
 static bool resctrl_enabled;
 
-bool resctrl_arch_alloc_capable(void)
-{
-	struct mpam_resctrl_res *res;
-	enum resctrl_res_level rid;
-
-	for_each_mpam_resctrl_control(res, rid) {
-		if (res->resctrl_res.alloc_capable)
-			return true;
-	}
-
-	return false;
-}
-
-bool resctrl_arch_mon_capable(void)
-{
-	struct mpam_resctrl_res *res = &mpam_resctrl_controls[RDT_RESOURCE_L3];
-	struct rdt_resource *l3 = &res->resctrl_res;
-
-	/* All monitors are presented as being on the L3 cache */
-	return l3->mon_capable;
-}
-
 bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)
 {
 	return false;
@@ -1902,9 +1880,9 @@ int mpam_resctrl_setup(void)
 
 	cpus_read_unlock();
 
-	if (!resctrl_arch_alloc_capable() && !resctrl_arch_mon_capable()) {
+	if (!resctrl_alloc_capable() && !resctrl_mon_capable()) {
 		pr_debug("No alloc(%u) or monitor(%u) found - resctrl not supported\n",
-			 resctrl_arch_alloc_capable(), resctrl_arch_mon_capable());
+			 resctrl_alloc_capable(), resctrl_mon_capable());
 		return -EOPNOTSUPP;
 	}
 
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 04e4ea612b7c..cb34d3637ee5 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -338,7 +338,7 @@ void free_rmid(u32 closid, u32 rmid)
 	 * allows architectures that ignore the closid parameter to avoid an
 	 * unnecessary check.
 	 */
-	if (!resctrl_arch_mon_capable() ||
+	if (!resctrl_mon_capable() ||
 	    idx == resctrl_arch_rmid_idx_encode(RESCTRL_RESERVED_CLOSID,
 						RESCTRL_RESERVED_RMID))
 		return;
@@ -888,7 +888,7 @@ void mbm_handle_overflow(struct work_struct *work)
 	 * If the filesystem has been unmounted this work no longer needs to
 	 * run.
 	 */
-	if (!resctrl_mounted || !resctrl_arch_mon_capable())
+	if (!resctrl_mounted || !resctrl_mon_capable())
 		goto out_unlock;
 
 	/*
@@ -950,7 +950,7 @@ void mbm_setup_overflow_handler(struct rdt_l3_mon_domain *dom, unsigned long del
 	 * When a domain comes online there is no guarantee the filesystem is
 	 * mounted. If not, there is no need to catch counter overflow.
 	 */
-	if (!resctrl_mounted || !resctrl_arch_mon_capable())
+	if (!resctrl_mounted || !resctrl_mon_capable())
 		return;
 	cpu = cpumask_any_housekeeping(&dom->hdr.cpu_mask, exclude_cpu);
 	dom->mbm_work_cpu = cpu;
@@ -966,7 +966,7 @@ int setup_rmid_lru_list(void)
 	u32 idx;
 	int i;
 
-	if (!resctrl_arch_mon_capable())
+	if (!resctrl_mon_capable())
 		return 0;
 
 	/*
@@ -1006,7 +1006,7 @@ int setup_rmid_lru_list(void)
 
 void free_rmid_lru_list(void)
 {
-	if (!resctrl_arch_mon_capable())
+	if (!resctrl_mon_capable())
 		return;
 
 	mutex_lock(&rdtgroup_mutex);
diff --git a/fs/resctrl/pseudo_lock.c b/fs/resctrl/pseudo_lock.c
index 56ab63f19bad..3d831227a42f 100644
--- a/fs/resctrl/pseudo_lock.c
+++ b/fs/resctrl/pseudo_lock.c
@@ -383,7 +383,7 @@ static int rdtgroup_locksetup_user_restrict(struct rdtgroup *rdtgrp)
 	if (ret)
 		goto err_cpus;
 
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		ret = rdtgroup_kn_mode_restrict(rdtgrp, "mon_groups");
 		if (ret)
 			goto err_cpus_list;
@@ -430,7 +430,7 @@ static int rdtgroup_locksetup_user_restore(struct rdtgroup *rdtgrp)
 	if (ret)
 		goto err_cpus;
 
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		ret = rdtgroup_kn_mode_restore(rdtgrp, "mon_groups", 0777);
 		if (ret)
 			goto err_cpus_list;
@@ -577,7 +577,7 @@ int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp)
 {
 	int ret;
 
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		ret = alloc_rmid(rdtgrp->closid);
 		if (ret < 0) {
 			rdt_last_cmd_puts("Out of RMIDs\n");
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 57ab090072c2..96a4978ce6b6 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -691,7 +691,7 @@ static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
 
 static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
 {
-	return (resctrl_arch_mon_capable() && (r->type == RDTMON_GROUP) &&
+	return (resctrl_mon_capable() && (r->type == RDTMON_GROUP) &&
 		resctrl_arch_match_rmid(t, r->mon.parent->closid,
 					r->mon.rmid));
 }
@@ -3157,9 +3157,9 @@ static void resctrl_unmount(void)
 		resctrl_arch_reset_all_ctrls(r);
 
 	resctrl_fs_teardown();
-	if (resctrl_arch_alloc_capable())
+	if (resctrl_alloc_capable())
 		resctrl_arch_disable_alloc();
-	if (resctrl_arch_mon_capable())
+	if (resctrl_mon_capable())
 		resctrl_arch_disable_mon();
 	resctrl_mounted = false;
 	mutex_unlock(&rdtgroup_mutex);
@@ -3213,7 +3213,7 @@ static int rdt_get_tree(struct fs_context *fc)
 	if (ret)
 		goto out_schemata_free;
 
-	if (resctrl_arch_mon_capable())
+	if (resctrl_mon_capable())
 		flags |= RFTYPE_MON;
 
 	ret = rdtgroup_add_files(rdtgroup_default.kn, flags);
@@ -3226,7 +3226,7 @@ static int rdt_get_tree(struct fs_context *fc)
 	if (ret < 0)
 		goto out_closid_exit;
 
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		ret = mongroup_create_dir(rdtgroup_default.kn,
 					  &rdtgroup_default, "mon_groups",
 					  &kn_mongrp);
@@ -3246,12 +3246,12 @@ static int rdt_get_tree(struct fs_context *fc)
 	if (ret)
 		goto out_mondata;
 
-	if (resctrl_arch_alloc_capable())
+	if (resctrl_alloc_capable())
 		resctrl_arch_enable_alloc();
-	if (resctrl_arch_mon_capable())
+	if (resctrl_mon_capable())
 		resctrl_arch_enable_mon();
 
-	if (resctrl_arch_alloc_capable() || resctrl_arch_mon_capable())
+	if (resctrl_alloc_capable() || resctrl_mon_capable())
 		resctrl_mounted = true;
 
 	if (resctrl_is_mbm_enabled()) {
@@ -3294,10 +3294,10 @@ static int rdt_get_tree(struct fs_context *fc)
 	return ret;
 
 out_mondata:
-	if (resctrl_arch_mon_capable())
+	if (resctrl_mon_capable())
 		kernfs_remove(kn_mondata);
 out_mongrp:
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		mon_put_kn_priv();
 		rdtgroup_unassign_cntrs(&rdtgroup_default);
 		kernfs_remove(kn_mongrp);
@@ -3886,7 +3886,7 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
 {
 	int ret;
 
-	if (!resctrl_arch_mon_capable())
+	if (!resctrl_mon_capable())
 		return 0;
 
 	ret = alloc_rmid(rdtgrp->closid);
@@ -3911,7 +3911,7 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
 
 static void mkdir_rdt_prepare_rmid_free(struct rdtgroup *rgrp)
 {
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		rdtgroup_unassign_cntrs(rgrp);
 		free_rmid(rgrp->closid, rgrp->mon.rmid);
 	}
@@ -4002,7 +4002,7 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 
 	if (rtype == RDTCTRL_GROUP) {
 		files = RFTYPE_BASE | RFTYPE_CTRL;
-		if (resctrl_arch_mon_capable())
+		if (resctrl_mon_capable())
 			files |= RFTYPE_MON;
 	} else {
 		files = RFTYPE_BASE | RFTYPE_MON;
@@ -4111,7 +4111,7 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
 
 	list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);
 
-	if (resctrl_arch_mon_capable()) {
+	if (resctrl_mon_capable()) {
 		/*
 		 * Create an empty mon_groups directory to hold the subset
 		 * of tasks and cpus to monitor.
@@ -4152,11 +4152,11 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
 	 * allocation is supported, add a control and monitoring
 	 * subdirectory
 	 */
-	if (resctrl_arch_alloc_capable() && parent_kn == rdtgroup_default.kn)
+	if (resctrl_alloc_capable() && parent_kn == rdtgroup_default.kn)
 		return rdtgroup_mkdir_ctrl_mon(parent_kn, name, mode);
 
 	/* Else, attempt to add a monitoring subdirectory. */
-	if (resctrl_arch_mon_capable())
+	if (resctrl_mon_capable())
 		return rdtgroup_mkdir_mon(parent_kn, name, mode);
 
 	return -EPERM;
@@ -4571,7 +4571,7 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *h
 	 * If resctrl is mounted, remove all the
 	 * per domain monitor data directories.
 	 */
-	if (resctrl_mounted && resctrl_arch_mon_capable())
+	if (resctrl_mounted && resctrl_mon_capable())
 		rmdir_mondata_subdir_allrdtgrp(r, hdr);
 
 	if (r->rid != RDT_RESOURCE_L3)
@@ -4708,7 +4708,7 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr
 	 * by rdt_get_tree() calling mkdir_mondata_all().
 	 * If resctrl is mounted, add per domain monitor data directories.
 	 */
-	if (resctrl_mounted && resctrl_arch_mon_capable())
+	if (resctrl_mounted && resctrl_mon_capable())
 		mkdir_mondata_subdir_allrdtgrp(r, hdr);
 
 out_unlock:
-- 
2.56.0

[PATCH v14 07/24] x86/resctrl: Update special case for Intel Haswell enumeration

[Tony Luck]

Certain Intel Haswell CPUs support L3 cache allocation but do not enumerate the
feature. A quirk probes for support and provides hard-coded parameters. The
quirk sets both the L3 resource and the global rdt_alloc_capable, but only
the global is used to signal that normal enumeration can be skipped.

Setting the global in the quirk is redundant. The quirk runs before
allocation enumeration and is the only code that can mark a resource as
allocation capable that early, so finding any allocation capable resource
at the start of enumeration already identifies the quirk case.

Stop setting rdt_alloc_capable in the quirk and skip allocation enumeration
when resctrl_alloc_capable() reports a resource is already allocation
capable, in preparation for removing the global.

No functional change intended.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Updated commit comment in context, problem, solution form.
---
 arch/x86/kernel/cpu/resctrl/core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index f0cfb37482d3..f2bf160d01c1 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -177,8 +177,6 @@ static inline void cache_alloc_hsw_probe(void)
 	r->cache.min_cbm_bits = 2;
 	r->cache.arch_has_sparse_bitmasks = false;
 	r->alloc_capable = true;
-
-	rdt_alloc_capable = true;
 }
 
 /*
@@ -930,7 +928,11 @@ static __init bool get_rdt_alloc_resources(void)
 	struct rdt_resource *r;
 	bool ret = false;
 
-	if (rdt_alloc_capable)
+	/*
+	 * On Haswell systems cache_alloc_hsw_probe() already marked
+	 * RDT_RESOURCE_L3 as alloc_capable. No further enumeration is needed.
+	 */
+	if (resctrl_alloc_capable())
 		return true;
 
 	if (!boot_cpu_has(X86_FEATURE_RDT_A))
-- 
2.56.0

[PATCH v14 08/24] x86/resctrl: Delete rdt_alloc_capable and rdt_mon_capable

[Tony Luck]

Whether the system supports allocation or monitoring is now determined from
the per-resource capability flags via resctrl_alloc_capable() and
resctrl_mon_capable(). The x86 globals rdt_alloc_capable and
rdt_mon_capable are still written during enumeration and when telemetry
monitoring is discovered at mount time, but nothing reads them.

Every place that writes a global also sets the matching resource flag, so
the globals carry no information that the resource flags do not.

Delete rdt_alloc_capable and rdt_mon_capable.

No functional change intended.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message in context, problem, solution format.
---
 arch/x86/include/asm/resctrl.h        |  2 --
 arch/x86/kernel/cpu/resctrl/core.c    | 13 +++----------
 arch/x86/kernel/cpu/resctrl/monitor.c |  6 ------
 3 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 9c44a7766631..8c3b51398ddc 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -42,8 +42,6 @@ struct resctrl_pqr_state {
 
 DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
 
-extern bool rdt_alloc_capable;
-extern bool rdt_mon_capable;
 extern unsigned int rdt_l3_mon_scale;
 
 DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index f2bf160d01c1..2e3b9c16cbda 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -45,12 +45,6 @@ static DEFINE_MUTEX(domain_list_lock);
  */
 DEFINE_PER_CPU(struct resctrl_pqr_state, pqr_state);
 
-/*
- * Global boolean for rdt_alloc which is true if any
- * resource allocation is enabled.
- */
-bool rdt_alloc_capable;
-
 static void mba_wrmsr_intel(struct msr_param *m);
 static void cat_wrmsr(struct msr_param *m);
 static void mba_wrmsr_amd(struct msr_param *m);
@@ -781,7 +775,6 @@ void resctrl_arch_pre_mount(void)
 	cpus_read_lock();
 	mutex_lock(&domain_list_lock);
 	r->mon_capable = true;
-	rdt_mon_capable = true;
 	for_each_online_cpu(cpu)
 		domain_add_cpu_mon(cpu, r);
 	mutex_unlock(&domain_list_lock);
@@ -1026,10 +1019,10 @@ static __init void check_quirks(void)
 
 static __init bool get_rdt_resources(void)
 {
-	rdt_alloc_capable = get_rdt_alloc_resources();
-	rdt_mon_capable = get_rdt_mon_resources();
+	bool alloc = get_rdt_alloc_resources();
+	bool mon = get_rdt_mon_resources();
 
-	return (rdt_mon_capable || rdt_alloc_capable);
+	return alloc || mon;
 }
 
 static __init void rdt_init_res_defs_intel(void)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 468e9821f35a..82a555855c1b 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -26,12 +26,6 @@
 
 #include "internal.h"
 
-/*
- * Global boolean for rdt_monitor which is true if any
- * resource monitoring is enabled.
- */
-bool rdt_mon_capable;
-
 /*
  * Scale factor to convert L3 monitor events to bytes.
  */
-- 
2.56.0

[PATCH v14 09/24] fs/resctrl: Remove redundant calls to resctrl_mon_capable()

[Tony Luck]

resctrl_mon_capable() reports whether the system supports monitoring by
scanning all resources. On x86 it used to read a single architecture-provided
flag. Calls on paths that run repeatedly now pay for the scan.

Two such callers already know that monitoring is supported:

1) mbm_handle_overflow()
The MBM overflow handler runs once per second on each L3 monitoring
domain. It is only set up when MBM events are enabled, which requires
L3 monitoring support.

2) is_rmid_match()
Called for every task in the system when walking the task list to read
a tasks file, remove a group, or unmount. It only matches MON groups,
which can only be created on a system that supports monitoring.

Remove the call to resctrl_mon_capable() from both functions.

No functional change intended.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message confessing that this is fixing a performance
	problem created by an earlier patch this series.
---
 fs/resctrl/monitor.c  | 2 +-
 fs/resctrl/rdtgroup.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index cb34d3637ee5..f05be52ab5b3 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -888,7 +888,7 @@ void mbm_handle_overflow(struct work_struct *work)
 	 * If the filesystem has been unmounted this work no longer needs to
 	 * run.
 	 */
-	if (!resctrl_mounted || !resctrl_mon_capable())
+	if (!resctrl_mounted)
 		goto out_unlock;
 
 	/*
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 96a4978ce6b6..7cf809380c53 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -691,7 +691,7 @@ static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
 
 static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
 {
-	return (resctrl_mon_capable() && (r->type == RDTMON_GROUP) &&
+	return (r->type == RDTMON_GROUP &&
 		resctrl_arch_match_rmid(t, r->mon.parent->closid,
 					r->mon.rmid));
 }
-- 
2.56.0

[PATCH v14 10/24] x86/resctrl: Honor rdt={perf|energy} options to force enable AET events

[Tony Luck]

resctrl can disable a feature the platform supports, for example because
of an erratum or, for Application Energy Telemetry (AET), because an event
group has insufficient RMIDs. The "rdt=" kernel command line option lets
the user force such a feature on anyway, and also lets the user disable
supported features they do not need.

resctrl enumerates AET once, on first mount. Enumeration skips an event
group that is marked disabled. An event group with insufficient RMIDs is
marked disabled even when the user forced it on, but this happens after
the test for forced off when enumeration begins for an event group.

This will be broken when AET is enumerated on every mount. The disable mark
recorded for insufficient RMIDs on one mount causes the event group to be
skipped on the next, ignoring the user's explicit rdt= request to enable it.

In preparation for enumerating AET on every mount, skip a disabled event
group only if the user has not forced it on. As a result, when the command
line both disables and enables the same event group, for example
"rdt=!perf,perf:<guid>", enabling now takes precedence. This matches how
rdt= handles the other resctrl features.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message. Dropped previous supplied Reinette RB tag.
---
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 66cd8c2c7a51..9f0829a82cb0 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -262,7 +262,7 @@ static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
 	int skipped_events = 0;
 
-	if (e->force_off)
+	if (e->force_off && !e->force_on)
 		return false;
 
 	if (!group_has_usable_regions(e, p))
-- 
2.56.0

[PATCH v14 11/24] fs/resctrl: Add interface to disable a monitor event

[Tony Luck]

resctrl assumes that every monitor event is enabled before any domain is
created, since domains are created from CPU hotplug callbacks and their
per-domain state depends on the events enabled at that time. Events, once
enabled, stay enabled.

resctrl enumerates Application Energy Telemetry (AET) events from data provided
by the pmt_telemetry driver, which currently must be built in. Allowing the
driver to be a loadable module means AET events must be enumerated on every
mount and disabled again on unmount, so the driver can be unloaded while
resctrl is not mounted. There is no way to disable an event.

Add resctrl_disable_mon_event(). The architecture owns domain lifetime, so
it is responsible for calling this only while resctrl is unmounted and for
cleaning up any per-domain state. These requirements are not enforced in
code, so document them in kerneldoc, alongside the matching requirements
for enabling an event.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message. Dropped previous applied Reinette RB tag.
---
 include/linux/resctrl.h | 36 ++++++++++++++++++++++++++++++++++++
 fs/resctrl/monitor.c    | 15 +++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 0e7fce070fde..764c45be2d59 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -449,9 +449,45 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
 u32 resctrl_arch_system_num_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
+/**
+ * resctrl_enable_mon_event() - Enable monitoring event
+ * @eventid:	ID of the event.
+ * @any_cpu:	True if event data can be read from any CPU.
+ * @binary_bits: Number of binary places of the fixed-point value expected to
+ *		back a floating point event. Can only be set for floating point
+ *		events.
+ * @arch_priv:	Architecture private data associated with event. Passed back to
+ *		architecture when reading the event via resctrl_arch_rmid_read().
+ *
+ * The file system must not be mounted when enabling an event.
+ *
+ * Events that require per-domain (architectural and/or filesystem) state must
+ * be enabled before the domain structures are allocated. For example before
+ * CPU hotplug callbacks that allocate domain structures are registered. If the
+ * architecture discovers a resource after initialization it should enable
+ * events needing per-domain state before any domain structure allocation which
+ * should be coordinated with the CPU hotplug callbacks.
+ *
+ * Return:
+ * true if event was successfully enabled, false otherwise.
+ */
 bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
 			      unsigned int binary_bits, void *arch_priv);
 
+/**
+ * resctrl_disable_mon_event() - Disable monitoring event
+ * @eventid:	ID of the event
+ *
+ * Never disable an event while the file system is mounted. Never
+ * disable an event that may be accessed while the file system is
+ * unmounted.
+ *
+ * Events that require per-domain (architectural and/or filesystem) state
+ * will require additional cleanup which should be coordinated with the CPU
+ * hotplug callbacks.
+ */
+void resctrl_disable_mon_event(enum resctrl_event_id eventid);
+
 bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
 
 bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index f05be52ab5b3..fbbb31e9618b 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1068,6 +1068,21 @@ bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
 	return true;
 }
 
+void resctrl_disable_mon_event(enum resctrl_event_id eventid)
+{
+	if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >= QOS_NUM_EVENTS))
+		return;
+	if (!mon_event_all[eventid].enabled) {
+		pr_warn("Event %d already disabled\n", eventid);
+		return;
+	}
+
+	mon_event_all[eventid].any_cpu = false;
+	mon_event_all[eventid].binary_bits = 0;
+	mon_event_all[eventid].arch_priv = NULL;
+	mon_event_all[eventid].enabled = false;
+}
+
 bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid)
 {
 	return eventid >= QOS_FIRST_EVENT && eventid < QOS_NUM_EVENTS &&
-- 
2.56.0

[PATCH v14 12/24] arm,x86,fs/resctrl: Allocate maximum needed rmid_ptrs[]

[Tony Luck]

resctrl keeps per-RMID state in rmid_ptrs[]. It is allocated on first
mount, sized for the number of RMIDs available at that time, and reused by
every subsequent mount. The number of RMIDs available is the smallest
number supported across all monitoring resources.

Application Energy Telemetry (AET) requires the pmt_telemetry driver
to be built in. Allowing it to be a module means AET may contribute to
that smallest number on one mount and not on the next, so a later mount
may need more entries than the first mount allocated. Reallocating per
mount is not possible because the limbo handler continues to access
rmid_ptrs[] after resctrl is unmounted.

Size rmid_ptrs[] for the maximum number of RMIDs the system can ever need,
as reported by a new architecture hook. On x86 this is the number of RMIDs
supported by L3 monitoring if present, since that bounds the number
available on every mount, and otherwise the number of RMIDs that
MSR_IA32_PQR_ASSOC.RMID can hold.

Rebuild the free list on every mount from the RMIDs available for that
mount. Leave out RMIDs still dirty from an earlier mount, because the
limbo handler returns them to the free list once they are clean.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message.
---
 include/linux/resctrl.h            |  1 +
 arch/x86/kernel/cpu/resctrl/core.c | 27 +++++++++++++
 drivers/resctrl/mpam_resctrl.c     |  9 +++++
 fs/resctrl/monitor.c               | 64 ++++++++++++++++++++----------
 4 files changed, 79 insertions(+), 22 deletions(-)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 764c45be2d59..7afeb3bd55d9 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -447,6 +447,7 @@ static inline u32 resctrl_get_default_ctrl(struct rdt_resource *r)
 /* The number of closid supported by this resource regardless of CDP */
 u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
 u32 resctrl_arch_system_num_rmid_idx(void);
+u32 resctrl_arch_system_max_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
 /**
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 2e3b9c16cbda..8702a6da2374 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -45,6 +45,9 @@ static DEFINE_MUTEX(domain_list_lock);
  */
 DEFINE_PER_CPU(struct resctrl_pqr_state, pqr_state);
 
+/* Number of unique RMID values that can be written to MSR_IA32_PQR_ASSOC.RMID */
+static u32 pqr_assoc_num_rmid;
+
 static void mba_wrmsr_intel(struct msr_param *m);
 static void cat_wrmsr(struct msr_param *m);
 static void mba_wrmsr_amd(struct msr_param *m);
@@ -124,6 +127,28 @@ u32 resctrl_arch_system_num_rmid_idx(void)
 	return num_rmids == U32_MAX ? 0 : num_rmids;
 }
 
+/**
+ * resctrl_arch_system_max_rmid_idx - Largest possible RMID index
+ *
+ * Return: Largest possible RMID index used for boot time allocations.
+ */
+u32 resctrl_arch_system_max_rmid_idx(void)
+{
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+	u32 num_rmid = pqr_assoc_num_rmid;
+
+	/*
+	 * If the system is capable of L3 monitoring the maximum RMID value may
+	 * be lower than the system maximum. Either because the L3 monitoring
+	 * feature supports fewer RMIDs, or because SNC (Sub-NUMA Cluster)
+	 * is enabled and divides RMIDs per cluster.
+	 */
+	if (r->mon_capable)
+		num_rmid = r->mon.num_rmid;
+
+	return num_rmid;
+}
+
 struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l)
 {
 	if (l >= RDT_NUM_RESOURCES)
@@ -967,6 +992,8 @@ static __init bool get_rdt_mon_resources(void)
 	if (!cpu_feature_enabled(X86_FEATURE_CQM))
 		return false;
 
+	pqr_assoc_num_rmid = cpuid_ebx(0xf) + 1;
+
 	/* Any of the L3 monitoring features? */
 	if (!cpu_feature_enabled(X86_FEATURE_CQM_LLC))
 		return false;
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 7ddee8f5162f..52726f7fd03f 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -257,6 +257,15 @@ u32 resctrl_arch_system_num_rmid_idx(void)
 	return (mpam_pmg_max + 1) * (mpam_partid_max + 1);
 }
 
+/*
+ * File system calls this for one-time allocation of structures.
+ * Return the largest possible value.
+ */
+u32 resctrl_arch_system_max_rmid_idx(void)
+{
+	return resctrl_arch_system_num_rmid_idx();
+}
+
 u32 resctrl_arch_rmid_idx_encode(u32 closid, u32 rmid)
 {
 	return closid * (mpam_pmg_max + 1) + rmid;
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index fbbb31e9618b..647dad02fffd 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -75,6 +75,11 @@ static unsigned int rmid_limbo_count;
  */
 static struct rmid_entry	*rmid_ptrs;
 
+/*
+ * @num_rmid_ptrs - The number of elements in rmid_ptrs[].
+ */
+static u32 num_rmid_ptrs;
+
 /*
  * This is the threshold cache occupancy in bytes at which we will consider an
  * RMID available for re-allocation.
@@ -961,45 +966,60 @@ void mbm_setup_overflow_handler(struct rdt_l3_mon_domain *dom, unsigned long del
 
 int setup_rmid_lru_list(void)
 {
-	struct rmid_entry *entry = NULL;
-	u32 idx_limit;
-	u32 idx;
+	struct rmid_entry *entry;
+	u32 cur_idx_limit;
+	u32 rsvd_idx;
 	int i;
 
 	if (!resctrl_mon_capable())
 		return 0;
 
 	/*
-	 * Called on every mount, but the number of RMIDs cannot change
-	 * after the first mount, so keep using the same set of rmid_ptrs[]
-	 * until resctrl_exit(). Note that the limbo handler continues to
-	 * access rmid_ptrs[] after resctrl is unmounted.
+	 * Allocate the largest number of RMIDs that this system will ever
+	 * need. These cannot be freed until resctrl_exit() because the limbo
+	 * handler continues to access rmid_ptrs[] after resctrl is unmounted.
 	 */
-	if (rmid_ptrs)
-		return 0;
+	if (!rmid_ptrs) {
+		num_rmid_ptrs = resctrl_arch_system_max_rmid_idx();
+		rmid_ptrs = kzalloc_objs(struct rmid_entry, num_rmid_ptrs);
+		if (!rmid_ptrs) {
+			num_rmid_ptrs = 0;
+			return -ENOMEM;
+		}
 
-	idx_limit = resctrl_arch_system_num_rmid_idx();
-	rmid_ptrs = kzalloc_objs(struct rmid_entry, idx_limit);
-	if (!rmid_ptrs)
-		return -ENOMEM;
+		for (i = 0; i < num_rmid_ptrs; i++) {
+			entry = &rmid_ptrs[i];
+			INIT_LIST_HEAD(&entry->list);
 
-	for (i = 0; i < idx_limit; i++) {
-		entry = &rmid_ptrs[i];
-		INIT_LIST_HEAD(&entry->list);
+			resctrl_arch_rmid_idx_decode(i, &entry->closid, &entry->rmid);
+		}
+	}
 
-		resctrl_arch_rmid_idx_decode(i, &entry->closid, &entry->rmid);
-		list_add_tail(&entry->list, &rmid_free_lru);
+	/* Find how many RMIDs are available for this mount */
+	cur_idx_limit = resctrl_arch_system_num_rmid_idx();
+	if (cur_idx_limit > num_rmid_ptrs) {
+		pr_warn_once("RMID count %u exceeds allocation. Limit to %u\n",
+			     cur_idx_limit, num_rmid_ptrs);
+		cur_idx_limit = num_rmid_ptrs;
 	}
 
+	INIT_LIST_HEAD(&rmid_free_lru);
+
 	/*
 	 * RESCTRL_RESERVED_CLOSID and RESCTRL_RESERVED_RMID are special and
 	 * are always allocated. These are used for the rdtgroup_default
 	 * control group, which was setup earlier in rdtgroup_setup_default().
 	 */
-	idx = resctrl_arch_rmid_idx_encode(RESCTRL_RESERVED_CLOSID,
-					   RESCTRL_RESERVED_RMID);
-	entry = __rmid_entry(idx);
-	list_del(&entry->list);
+	rsvd_idx = resctrl_arch_rmid_idx_encode(RESCTRL_RESERVED_CLOSID,
+						RESCTRL_RESERVED_RMID);
+
+	for (i = 0; i < cur_idx_limit; i++) {
+		entry = &rmid_ptrs[i];
+		/* Don't add reserved or busy entries to free list */
+		if (i == rsvd_idx || entry->busy)
+			continue;
+		list_add_tail(&entry->list, &rmid_free_lru);
+	}
 
 	return 0;
 }
-- 
2.56.0

[PATCH v14 13/24] arm,x86,fs/resctrl: Use right size for L3 monitor data structures

[Tony Luck]

On x86 the number of RMIDs available for use is the smallest number of RMIDs
supported by any resource that supports monitoring.

Each L3 monitoring domain has structures with one entry per RMID index,
allocated when the domain comes online and kept across mounts of the resctrl
file system:

* the bitmap of RMIDs in limbo with L3 occupancy above the threshold,
* the per-event state used by the "mba_MBps" software controller to compute
bandwidth,
* on x86, the per-event state that accumulates MBM counts across hardware
counter overflow.

The resctrl file system sizes and walks the first two using the number of
RMIDs available for use. x86 already sizes the third by the number of RMIDs
supported by L3 monitoring.

The number of RMIDs available for use does not currently change between
mounts because Application Energy Telemetry (AET) is enumerated only once. In
preparation for building the pmt_telemetry driver as a module, AET will be
enumerated on every mount, and its events will be available only when the
driver is loaded at that time. The number of RMIDs available for use can
then change between mounts while the L3 domain structures stay allocated. A
domain that comes online while the number is small would be too small for a
later mount. RMIDs that are still in limbo at unmount may also be beyond the
number of RMIDs available for the next mount.

Add resctrl_arch_get_num_rmid_idx() for the architecture to report the
number of RMID indexes a resource supports, which does not change between
mounts. On x86 this is the number of RMIDs supported by L3 monitoring. MPAM
keeps reporting the system-wide number. Use it to size and walk the L3
domain structures.

Keep checking every RMID supported by L3 for limbo. Do not return an RMID
to the free list when it is beyond the number of RMIDs available for the
current mount.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message.
---
 include/linux/resctrl.h            |  7 +++++--
 arch/x86/kernel/cpu/resctrl/core.c |  5 +++++
 drivers/resctrl/mpam_resctrl.c     |  5 +++++
 fs/resctrl/monitor.c               | 22 ++++++++++++++++++----
 fs/resctrl/rdtgroup.c              |  2 +-
 5 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 7afeb3bd55d9..c77e24c0d8b6 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -183,10 +183,12 @@ struct mbm_cntr_cfg {
  * struct rdt_l3_mon_domain - group of CPUs sharing RDT_RESOURCE_L3 monitoring
  * @hdr:		common header for different domain types
  * @ci_id:		cache info id for this domain
- * @rmid_busy_llc:	bitmap of which limbo RMIDs are above threshold
+ * @rmid_busy_llc:	bitmap of which limbo RMIDs are above threshold. Sized for
+ *			maximum supported RMIDs in L3 resource.
  * @mbm_states:		Per-event pointer to the MBM event's saved state.
  *			An MBM event's state is an array of struct mbm_state
  *			indexed by RMID on x86 or combined CLOSID, RMID on Arm.
+ *			Sized same as @rmid_busy_llc.
  * @mbm_over:		worker to periodically read MBM h/w counters
  * @cqm_limbo:		worker to periodically read CQM h/w counters
  * @mbm_work_cpu:	worker CPU for MBM h/w counters
@@ -444,8 +446,9 @@ static inline u32 resctrl_get_default_ctrl(struct rdt_resource *r)
 	return WARN_ON_ONCE(1);
 }
 
-/* The number of closid supported by this resource regardless of CDP */
+/* The number of closid/rmid supported by this resource regardless of CDP */
 u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
+u32 resctrl_arch_get_num_rmid_idx(struct rdt_resource *r);
 u32 resctrl_arch_system_num_rmid_idx(void);
 u32 resctrl_arch_system_max_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 8702a6da2374..b32fa143283e 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -380,6 +380,11 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r)
 	return resctrl_to_arch_res(r)->num_closid;
 }
 
+u32 resctrl_arch_get_num_rmid_idx(struct rdt_resource *r)
+{
+	return r->mon.num_rmid;
+}
+
 void rdt_ctrl_update(void *arg)
 {
 	struct rdt_hw_resource *hw_res;
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 52726f7fd03f..360a50eb0cd3 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -252,6 +252,11 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored)
 	return mpam_partid_max + 1;
 }
 
+u32 resctrl_arch_get_num_rmid_idx(struct rdt_resource *ignored)
+{
+	return resctrl_arch_system_num_rmid_idx();
+}
+
 u32 resctrl_arch_system_num_rmid_idx(void)
 {
 	return (mpam_pmg_max + 1) * (mpam_partid_max + 1);
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 647dad02fffd..4c7308c84657 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -120,10 +120,18 @@ static inline struct rmid_entry *__rmid_entry(u32 idx)
 
 static void limbo_release_entry(struct rmid_entry *entry)
 {
+	u32 cur_idx_limit = resctrl_arch_system_num_rmid_idx();
+
 	lockdep_assert_held(&rdtgroup_mutex);
 
 	rmid_limbo_count--;
-	list_add_tail(&entry->list, &rmid_free_lru);
+
+	/*
+	 * Limbo may be freeing an RMID from a previous mount where there
+	 * were more RMIDs available.
+	 */
+	if (resctrl_arch_rmid_idx_encode(entry->closid, entry->rmid) < cur_idx_limit)
+		list_add_tail(&entry->list, &rmid_free_lru);
 
 	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID))
 		closid_num_dirty_rmid[entry->closid]--;
@@ -138,7 +146,7 @@ static void limbo_release_entry(struct rmid_entry *entry)
 void __check_limbo(struct rdt_l3_mon_domain *d, bool force_free)
 {
 	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
-	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
+	u32 idx_limit = resctrl_arch_get_num_rmid_idx(r);
 	struct rmid_entry *entry;
 	bool rmid_dirty = true;
 	u32 idx, cur_idx = 1;
@@ -159,6 +167,11 @@ void __check_limbo(struct rdt_l3_mon_domain *d, bool force_free)
 	 * are marked as busy for occupancy < threshold. If the occupancy
 	 * is less than the threshold decrement the busy counter of the
 	 * RMID and move it to the free list when the counter reaches 0.
+	 *
+	 * RMIDs will keep counts of allocated LLC entries after the resctrl
+	 * file system is unmounted. So check all possible RMIDs since a
+	 * previous mount cycle may have used more than are available in
+	 * this mount cycle.
 	 */
 	for (;;) {
 		idx = find_next_bit(d->rmid_busy_llc, idx_limit, cur_idx);
@@ -202,7 +215,8 @@ void __check_limbo(struct rdt_l3_mon_domain *d, bool force_free)
 
 bool has_busy_rmid(struct rdt_l3_mon_domain *d)
 {
-	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
+	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+	u32 idx_limit = resctrl_arch_get_num_rmid_idx(r);
 
 	return find_first_bit(d->rmid_busy_llc, idx_limit) != idx_limit;
 }
@@ -1240,7 +1254,7 @@ static void mbm_cntr_free_all(struct rdt_resource *r, struct rdt_l3_mon_domain *
  */
 static void resctrl_reset_rmid_all(struct rdt_resource *r, struct rdt_l3_mon_domain *d)
 {
-	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
+	u32 idx_limit = resctrl_arch_get_num_rmid_idx(r);
 	enum resctrl_event_id evt;
 	int idx;
 
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 7cf809380c53..79d4ddc3d64d 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -4619,7 +4619,7 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *h
  */
 static int domain_setup_l3_mon_state(struct rdt_resource *r, struct rdt_l3_mon_domain *d)
 {
-	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
+	u32 idx_limit = resctrl_arch_get_num_rmid_idx(r);
 	size_t tsize = sizeof(*d->mbm_states[0]);
 	enum resctrl_event_id eventid;
 	int idx;
-- 
2.56.0

[PATCH v14 14/24] x86,fs/resctrl: Handle systems where AET is the only monitoring feature

[Tony Luck]

Application Energy Telemetry (AET) is not enumerated via CPUID. Its presence
is discovered on the first mount of the resctrl file system by querying the
pmt_telemetry driver. resctrl is initialized at boot only if CPUID
enumeration finds allocation or monitoring features.

On a system that supports monitoring (X86_FEATURE_CQM) but no L3 monitoring
features, get_rdt_mon_resources() reports that no monitoring is supported.
If the system also does not support allocation, resctrl is not initialized
and AET can never be used.

Assume that AET may be supported whenever the system supports monitoring.

If AET is not supported either, the mount finds neither allocation nor
monitoring support. rdt_get_tree() then lets the mount succeed with nothing
to allocate or monitor, but does not mark resctrl as mounted. Fail the mount
with an error message instead, before any of the file system is set up.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message.
---
 arch/x86/kernel/cpu/resctrl/internal.h |  2 +-
 arch/x86/kernel/cpu/resctrl/core.c     | 22 +++++++++++++---------
 arch/x86/kernel/cpu/resctrl/monitor.c  |  4 +---
 fs/resctrl/rdtgroup.c                  |  8 ++++++--
 4 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 086282a82fca..c038b7d80ce3 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -226,7 +226,7 @@ union l3_qos_abmc_cfg {
 
 void rdt_ctrl_update(void *arg);
 
-int rdt_get_l3_mon_config(struct rdt_resource *r);
+void rdt_get_l3_mon_config(struct rdt_resource *r);
 
 bool rdt_cpu_has(int flag);
 
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index b32fa143283e..0262174df7ad 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -991,7 +991,7 @@ static __init bool get_rdt_alloc_resources(void)
 static __init bool get_rdt_mon_resources(void)
 {
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
-	bool ret = false;
+	bool l3_mon_found = false;
 
 	/* Any monitoring at all? */
 	if (!cpu_feature_enabled(X86_FEATURE_CQM))
@@ -1001,27 +1001,31 @@ static __init bool get_rdt_mon_resources(void)
 
 	/* Any of the L3 monitoring features? */
 	if (!cpu_feature_enabled(X86_FEATURE_CQM_LLC))
-		return false;
+		goto out;
 
 	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
 		resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL);
-		ret = true;
+		l3_mon_found = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
 		resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false, 0, NULL);
-		ret = true;
+		l3_mon_found = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
 		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false, 0, NULL);
-		ret = true;
+		l3_mon_found = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_ABMC))
-		ret = true;
+		l3_mon_found = true;
 
-	if (!ret)
-		return false;
+	if (l3_mon_found)
+		rdt_get_l3_mon_config(r);
+	else
+		pr_info("CPUID reports L3 monitoring support, but no L3 monitoring features found\n");
 
-	return !rdt_get_l3_mon_config(r);
+out:
+	/* Non-L3 features, e.g. AET, may be supported */
+	return true;
 }
 
 static __init void __check_quirks_intel(void)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 82a555855c1b..bd45d72d1d05 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -431,7 +431,7 @@ static void __init intel_rdt_mbm_apply_quirk(u32 num_rmid)
 	mbm_cf = mbm_cf_table[cf_index].cf;
 }
 
-int __init rdt_get_l3_mon_config(struct rdt_resource *r)
+void __init rdt_get_l3_mon_config(struct rdt_resource *r)
 {
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 	unsigned int mbm_offset;
@@ -519,8 +519,6 @@ int __init rdt_get_l3_mon_config(struct rdt_resource *r)
 		intel_rdt_mbm_apply_quirk(num_rmid);
 
 	r->mon_capable = true;
-
-	return 0;
 }
 
 static void resctrl_abmc_set_one_amd(void *arg)
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 79d4ddc3d64d..ecdb5da50179 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -3193,6 +3193,11 @@ static int rdt_get_tree(struct fs_context *fc)
 		goto out;
 	}
 
+	if (!resctrl_alloc_capable() && !resctrl_mon_capable()) {
+		ret = invalfc(fc, "No allocation or monitoring features are available or enabled");
+		goto out;
+	}
+
 	ret = setup_rmid_lru_list();
 	if (ret)
 		goto out;
@@ -3251,8 +3256,7 @@ static int rdt_get_tree(struct fs_context *fc)
 	if (resctrl_mon_capable())
 		resctrl_arch_enable_mon();
 
-	if (resctrl_alloc_capable() || resctrl_mon_capable())
-		resctrl_mounted = true;
+	resctrl_mounted = true;
 
 	if (resctrl_is_mbm_enabled()) {
 		r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
-- 
2.56.0

[PATCH v14 15/24] x86/resctrl: Add PMT registration API for AET enumeration callbacks

[Tony Luck]

resctrl is always built in and calls into the pmt_telemetry driver to
enumerate Application Energy Telemetry (AET) features. Built-in code cannot
call directly into a module, so AET support requires
CONFIG_INTEL_PMT_TELEMETRY=y.

In preparation for allowing pmt_telemetry to be built as a module, add and
export functions with which pmt_telemetry registers its enumeration
callbacks when it is loaded and unregisters them when it is unloaded.
Record the registering module so that resctrl can hold a reference on it
while it uses the callbacks.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message.
---
 include/linux/intel_vsec.h              | 12 ++++++++++++
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 24 ++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
index 843cda8f8644..c04b1d0f3143 100644
--- a/include/linux/intel_vsec.h
+++ b/include/linux/intel_vsec.h
@@ -257,4 +257,16 @@ static inline void
 intel_pmt_put_feature_group(struct pmt_feature_group *feature_group) {}
 #endif
 
+#ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET
+void intel_aet_register_enumeration(struct module *module,
+				    struct pmt_feature_group *(*get)(enum pmt_feature_id id),
+				    void (*put)(struct pmt_feature_group *p));
+void intel_aet_unregister_enumeration(void);
+#else
+static inline void intel_aet_register_enumeration(struct module *module,
+						  struct pmt_feature_group *(*get)(enum pmt_feature_id id),
+						  void (*put)(struct pmt_feature_group *p)) { }
+static inline void intel_aet_unregister_enumeration(void) { }
+#endif /* CONFIG_X86_CPU_RESCTRL_INTEL_AET */
+
 #endif
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 9f0829a82cb0..996a7ee544bf 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -17,12 +17,14 @@
 #include <linux/cpumask.h>
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/export.h>
 #include <linux/gfp_types.h>
 #include <linux/init.h>
 #include <linux/intel_pmt_features.h>
 #include <linux/intel_vsec.h>
 #include <linux/io.h>
 #include <linux/minmax.h>
+#include <linux/module.h>
 #include <linux/printk.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
@@ -325,6 +327,10 @@ static enum pmt_feature_id lookup_pfid(const char *pfname)
 	return FEATURE_INVALID;
 }
 
+static struct module *pmt_module;
+static struct pmt_feature_group *(*get_feature)(enum pmt_feature_id id);
+static void (*put_feature)(struct pmt_feature_group *p);
+
 /*
  * Request a copy of struct pmt_feature_group for each event group. If there is
  * one, the returned structure has an array of telemetry_region structures,
@@ -359,6 +365,24 @@ bool intel_aet_get_events(void)
 	return ret;
 }
 
+void intel_aet_register_enumeration(struct module *module,
+				    struct pmt_feature_group *(*get)(enum pmt_feature_id id),
+				    void (*put)(struct pmt_feature_group *p))
+{
+	get_feature = get;
+	put_feature = put;
+	pmt_module = module;
+}
+EXPORT_SYMBOL_NS_GPL(intel_aet_register_enumeration, "INTEL_PMT");
+
+void intel_aet_unregister_enumeration(void)
+{
+	pmt_module = NULL;
+	get_feature = NULL;
+	put_feature = NULL;
+}
+EXPORT_SYMBOL_NS_GPL(intel_aet_unregister_enumeration, "INTEL_PMT");
+
 void __exit intel_aet_exit(void)
 {
 	struct event_group **peg;
-- 
2.56.0

[PATCH v14 16/24] platform/x86/intel/pmt: Register enumeration functions with resctrl

[Tony Luck]

resctrl enumerates Application Energy Telemetry (AET) features by calling
pmt_telemetry functions directly, which requires pmt_telemetry to be built
in. resctrl now provides functions with which pmt_telemetry can register
those enumeration functions instead.

Register the enumeration functions with resctrl when pmt_telemetry is
loaded, in preparation for resctrl calling them through the registration
and for pmt_telemetry being built as a module.

Register only after the driver has probed all telemetry devices so that resctrl
does not enumerate a partial set. Force synchronous probing to avoid issues
if kernel command line or module parameter requests asynchronous operation.

Unregister the enumeration functions before tearing down the telemetry
devices on unload, so that resctrl cannot start enumeration while they are
being removed.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit message.
---
 drivers/platform/x86/intel/pmt/telemetry.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel/pmt/telemetry.c b/drivers/platform/x86/intel/pmt/telemetry.c
index 953f35b6daec..57eb2967a4d0 100644
--- a/drivers/platform/x86/intel/pmt/telemetry.c
+++ b/drivers/platform/x86/intel/pmt/telemetry.c
@@ -427,16 +427,29 @@ static struct auxiliary_driver pmt_telem_aux_driver = {
 	.id_table	= pmt_telem_id_table,
 	.remove		= pmt_telem_remove,
 	.probe		= pmt_telem_probe,
+	.driver		= {
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
+	},
 };
 
 static int __init pmt_telem_init(void)
 {
-	return auxiliary_driver_register(&pmt_telem_aux_driver);
+	int ret;
+
+	ret = auxiliary_driver_register(&pmt_telem_aux_driver);
+	if (ret)
+		return ret;
+
+	intel_aet_register_enumeration(THIS_MODULE, intel_pmt_get_regions_by_feature,
+				       intel_pmt_put_feature_group);
+
+	return 0;
 }
 module_init(pmt_telem_init);
 
 static void __exit pmt_telem_exit(void)
 {
+	intel_aet_unregister_enumeration();
 	auxiliary_driver_unregister(&pmt_telem_aux_driver);
 	xa_destroy(&telem_array);
 }
-- 
2.56.0

[PATCH v14 17/24] x86/resctrl: Use registered function pointers for AET enumeration

[Tony Luck]

resctrl enumerates Application Energy Telemetry (AET) features by calling
pmt_telemetry functions directly. pmt_telemetry now also registers these
functions with resctrl when it is loaded.

Calling them directly requires pmt_telemetry to be built in.

In preparation for pmt_telemetry being built as a loadable module, call the
registered functions instead. Serialize registration and unregistration
against enumeration. Take a reference on the pmt_telemetry module before
enumerating, so that the functions cannot be unregistered while resctrl
uses them.

AET support still requires pmt_telemetry to be built in, so it does not yet
matter that the module reference is never dropped after a successful
enumeration. It must be dropped on unmount before pmt_telemetry can be built
as a module.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Updates to resolve locking problems reported by Sashiko in v13.

	AET is now going to use a single mutex for both registration
	and in a later patch for device removal. So change the name
	from aet_register_lock to just aet_lock.

	Reverse locking hierarchy between AET and pmt_telemetry.
	No longer OK to call into pmt_telemetry to enumerate
	features with the aet_lock held. Instead, make use of
	module pinning while holding aet_lock.

	New commit message
---
 arch/x86/kernel/cpu/resctrl/internal.h  |  4 +-
 arch/x86/kernel/cpu/resctrl/core.c      |  2 +-
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 59 ++++++++++++++++++++++---
 3 files changed, 57 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c038b7d80ce3..8406addc05f5 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -234,15 +234,15 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
 void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r);
 
 #ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET
-bool intel_aet_get_events(void);
 void __exit intel_aet_exit(void);
+bool intel_aet_pre_mount(void);
 int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
 void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
 				struct list_head *add_pos);
 bool intel_handle_aet_option(bool force_off, char *tok);
 #else
-static inline bool intel_aet_get_events(void) { return false; }
 static inline void __exit intel_aet_exit(void) { }
+static inline bool intel_aet_pre_mount(void) { return false; }
 static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
 {
 	return -EINVAL;
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 0262174df7ad..ac67b4523b2d 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -795,7 +795,7 @@ void resctrl_arch_pre_mount(void)
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
 	int cpu;
 
-	if (!intel_aet_get_events())
+	if (!intel_aet_pre_mount())
 		return;
 
 	/*
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 996a7ee544bf..26406e18d5ed 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -12,6 +12,7 @@
 #define pr_fmt(fmt)   "resctrl: " fmt
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/compiler_types.h>
 #include <linux/container_of.h>
 #include <linux/cpumask.h>
@@ -25,6 +26,7 @@
 #include <linux/io.h>
 #include <linux/minmax.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/printk.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
@@ -327,6 +329,18 @@ static enum pmt_feature_id lookup_pfid(const char *pfname)
 	return FEATURE_INVALID;
 }
 
+/*
+ * Serialises AET's view of pmt_telemetry:
+ *   - pmt_module, get_feature, put_feature
+ *   - every event_group's ->pfg
+ *
+ * Lock ordering with pmt/telemetry.c's ep_lock is ep_lock -> aet_lock.
+ * AET therefore must not call get_feature() (which takes ep_lock) while
+ * holding aet_lock. put_feature() does not take ep_lock and may be
+ * invoked with aet_lock held.
+ */
+static DEFINE_MUTEX(aet_lock);
+
 static struct module *pmt_module;
 static struct pmt_feature_group *(*get_feature)(enum pmt_feature_id id);
 static void (*put_feature)(struct pmt_feature_group *p);
@@ -342,7 +356,8 @@ static void (*put_feature)(struct pmt_feature_group *p);
  * struct pmt_feature_group to indicate that its events are successfully
  * enabled.
  */
-bool intel_aet_get_events(void)
+static bool aet_get_events(struct pmt_feature_group *(*get)(enum pmt_feature_id id),
+			   void (*put)(struct pmt_feature_group *p))
 {
 	struct pmt_feature_group *p;
 	enum pmt_feature_id pfid;
@@ -351,14 +366,16 @@ bool intel_aet_get_events(void)
 
 	for_each_event_group(peg) {
 		pfid = lookup_pfid((*peg)->pfname);
-		p = intel_pmt_get_regions_by_feature(pfid);
+		p = get(pfid);
 		if (IS_ERR_OR_NULL(p))
 			continue;
 		if (enable_events(*peg, p)) {
-			(*peg)->pfg = p;
+			scoped_guard(mutex, &aet_lock) {
+				(*peg)->pfg = p;
+			}
 			ret = true;
 		} else {
-			intel_pmt_put_feature_group(p);
+			put(p);
 		}
 	}
 
@@ -369,6 +386,7 @@ void intel_aet_register_enumeration(struct module *module,
 				    struct pmt_feature_group *(*get)(enum pmt_feature_id id),
 				    void (*put)(struct pmt_feature_group *p))
 {
+	guard(mutex)(&aet_lock);
 	get_feature = get;
 	put_feature = put;
 	pmt_module = module;
@@ -377,19 +395,50 @@ EXPORT_SYMBOL_NS_GPL(intel_aet_register_enumeration, "INTEL_PMT");
 
 void intel_aet_unregister_enumeration(void)
 {
+	guard(mutex)(&aet_lock);
 	pmt_module = NULL;
 	get_feature = NULL;
 	put_feature = NULL;
 }
 EXPORT_SYMBOL_NS_GPL(intel_aet_unregister_enumeration, "INTEL_PMT");
 
+bool intel_aet_pre_mount(void)
+{
+	struct pmt_feature_group *(*get)(enum pmt_feature_id id);
+	void (*put)(struct pmt_feature_group *p);
+	struct module *mod;
+
+	/*
+	 * Snapshot the callbacks and pin the pmt_telemetry module under
+	 * aet_lock. The module reference keeps pmt_telem_exit() from
+	 * running intel_aet_unregister_enumeration() and changing these
+	 * pointers, so the snapshot remains valid after dropping aet_lock.
+	 */
+	scoped_guard(mutex, &aet_lock) {
+		if (!get_feature || !put_feature)
+			return false;
+		if (!try_module_get(pmt_module))
+			return false;
+		mod = pmt_module;
+		get = get_feature;
+		put = put_feature;
+	}
+
+	if (!aet_get_events(get, put)) {
+		module_put(mod);
+		return false;
+	}
+
+	return true;
+}
+
 void __exit intel_aet_exit(void)
 {
 	struct event_group **peg;
 
 	for_each_event_group(peg) {
 		if ((*peg)->pfg) {
-			intel_pmt_put_feature_group((*peg)->pfg);
+			put_feature((*peg)->pfg);
 			(*peg)->pfg = NULL;
 		}
 	}
-- 
2.56.0

[PATCH v14 18/24] arm,x86,fs/resctrl: Enumerate AET on every resctrl mount

[Tony Luck]

Application Energy Telemetry (AET) is enumerated only on the first mount of
the resctrl file system. A successful enumeration takes a reference on the
pmt_telemetry module that is never dropped. This is harmless only because
AET support requires pmt_telemetry to be built in.

In preparation for pmt_telemetry being built as a module, hold the module
reference only while resctrl is mounted. resctrl must then enumerate AET on
every mount and release everything obtained from pmt_telemetry on every
unmount.

Call resctrl_arch_pre_mount() on every mount attempt. Add
resctrl_arch_unmount() for the architecture to undo it after a failed mount
or on unmount. Serialize both hooks with each other and with the check that
resctrl is not already mounted, so that enumeration only happens while
resctrl is not mounted. Use a new mutex because the hooks take
cpus_read_lock(), which nests outside rdtgroup_mutex.

On x86, if AET was enumerated, unmount disables the AET events, returns the
telemetry data to pmt_telemetry, drops the module reference and removes
the AET monitoring domains. Cleanup at resctrl exit is no longer needed.

Do not re-enable an event group that was disabled during mount because the
system supports too few RMIDs for it. The same check would disable it again
on the next mount.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit comment.
	aet_register_lock name changed to aet_lock.
	Babu: Add commit comment about event_group::force_off
---
 include/linux/resctrl.h                 | 10 +++++++--
 arch/x86/kernel/cpu/resctrl/internal.h  |  4 ++--
 arch/x86/kernel/cpu/resctrl/core.c      | 21 +++++++++++++++--
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 29 +++++++++++++++++++-----
 drivers/resctrl/mpam_resctrl.c          |  4 ++++
 fs/resctrl/rdtgroup.c                   | 30 ++++++++++++++++++++-----
 6 files changed, 81 insertions(+), 17 deletions(-)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index c77e24c0d8b6..c40d72e4a957 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -611,11 +611,17 @@ void resctrl_online_cpu(unsigned int cpu);
 void resctrl_offline_cpu(unsigned int cpu);
 
 /*
- * Architecture hook called at beginning of first file system mount attempt.
- * No locks are held.
+ * Architecture hook called at beginning of each file system mount attempt.
+ * Serialized against other mount and unmount attempts.
  */
 void resctrl_arch_pre_mount(void);
 
+/*
+ * Architecture hook called when mount fails, or on unmount.
+ * Serialized against other mount and unmount attempts.
+ */
+void resctrl_arch_unmount(void);
+
 /**
  * resctrl_arch_rmid_read() - Read the eventid counter corresponding to rmid
  *			      for this resource and domain.
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 8406addc05f5..c66954bc01e7 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -234,15 +234,15 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
 void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r);
 
 #ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET
-void __exit intel_aet_exit(void);
 bool intel_aet_pre_mount(void);
+void intel_aet_unmount(void);
 int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
 void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
 				struct list_head *add_pos);
 bool intel_handle_aet_option(bool force_off, char *tok);
 #else
-static inline void __exit intel_aet_exit(void) { }
 static inline bool intel_aet_pre_mount(void) { return false; }
+static inline void intel_aet_unmount(void) { }
 static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
 {
 	return -EINVAL;
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index ac67b4523b2d..40466f29e48e 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -811,6 +811,25 @@ void resctrl_arch_pre_mount(void)
 	cpus_read_unlock();
 }
 
+void resctrl_arch_unmount(void)
+{
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
+	int cpu;
+
+	if (!r->mon_capable)
+		return;
+
+	intel_aet_unmount();
+
+	cpus_read_lock();
+	mutex_lock(&domain_list_lock);
+	for_each_online_cpu(cpu)
+		domain_remove_cpu_mon(cpu, r);
+	r->mon_capable = false;
+	mutex_unlock(&domain_list_lock);
+	cpus_read_unlock();
+}
+
 enum {
 	RDT_FLAG_CMT,
 	RDT_FLAG_MBM_TOTAL,
@@ -1161,8 +1180,6 @@ late_initcall(resctrl_arch_late_init);
 
 static void __exit resctrl_arch_exit(void)
 {
-	intel_aet_exit();
-
 	cpuhp_remove_state(rdt_online);
 
 	resctrl_exit();
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 26406e18d5ed..75cd602d65ae 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -331,7 +331,7 @@ static enum pmt_feature_id lookup_pfid(const char *pfname)
 
 /*
  * Serialises AET's view of pmt_telemetry:
- *   - pmt_module, get_feature, put_feature
+ *   - pmt_module, get_feature, put_feature, pmt_in_use
  *   - every event_group's ->pfg
  *
  * Lock ordering with pmt/telemetry.c's ep_lock is ep_lock -> aet_lock.
@@ -345,6 +345,11 @@ static struct module *pmt_module;
 static struct pmt_feature_group *(*get_feature)(enum pmt_feature_id id);
 static void (*put_feature)(struct pmt_feature_group *p);
 
+/*
+ * Track whether pmt_telemetry enumeration succeeded during mount for use during unmount.
+ */
+static bool pmt_in_use;
+
 /*
  * Request a copy of struct pmt_feature_group for each event group. If there is
  * one, the returned structure has an array of telemetry_region structures,
@@ -429,19 +434,33 @@ bool intel_aet_pre_mount(void)
 		return false;
 	}
 
+	pmt_in_use = true;
+
 	return true;
 }
 
-void __exit intel_aet_exit(void)
+void intel_aet_unmount(void)
 {
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
 	struct event_group **peg;
 
+	guard(mutex)(&aet_lock);
+	if (!pmt_in_use)
+		return;
+
 	for_each_event_group(peg) {
-		if ((*peg)->pfg) {
-			put_feature((*peg)->pfg);
-			(*peg)->pfg = NULL;
+		struct event_group *e = *peg;
+
+		if (e->pfg) {
+			for (int i = 0; i < e->num_events; i++)
+				resctrl_disable_mon_event(e->evts[i].id);
+			put_feature(e->pfg);
+			e->pfg = NULL;
 		}
 	}
+	module_put(pmt_module);
+	pmt_in_use = false;
+	r->mon.num_rmid = 0;
 }
 
 #define DATA_VALID	BIT_ULL(63)
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 360a50eb0cd3..ecea2239afa4 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -121,6 +121,10 @@ void resctrl_arch_pre_mount(void)
 {
 }
 
+void resctrl_arch_unmount(void)
+{
+}
+
 bool resctrl_arch_get_cdp_enabled(enum resctrl_res_level rid)
 {
 	return mpam_resctrl_controls[rid].cdp_enabled;
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index ecdb5da50179..20e579067570 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -30,6 +30,9 @@
 
 #include "internal.h"
 
+/* Mutex protecting resctrl_mounted and mount/unmount operations */
+static DEFINE_MUTEX(resctrl_mount_lock);
+
 /* Mutex to protect rdtgroup access. */
 DEFINE_MUTEX(rdtgroup_mutex);
 
@@ -48,7 +51,10 @@ LIST_HEAD(resctrl_schema_all);
  */
 static LIST_HEAD(mon_data_kn_priv_list);
 
-/* The filesystem can only be mounted once. */
+/*
+ * The filesystem can only be mounted once. Can only be updated
+ * while holding both resctrl_mount_lock and rdtgroup_mutex.
+ */
 bool resctrl_mounted;
 
 /* Kernel fs node for "info" directory under root */
@@ -3147,6 +3153,7 @@ static void resctrl_unmount(void)
 {
 	struct rdt_resource *r;
 
+	mutex_lock(&resctrl_mount_lock);
 	cpus_read_lock();
 	mutex_lock(&rdtgroup_mutex);
 
@@ -3164,6 +3171,8 @@ static void resctrl_unmount(void)
 	resctrl_mounted = false;
 	mutex_unlock(&rdtgroup_mutex);
 	cpus_read_unlock();
+	resctrl_arch_unmount();
+	mutex_unlock(&resctrl_mount_lock);
 }
 
 static int rdt_get_tree(struct fs_context *fc)
@@ -3175,24 +3184,27 @@ static int rdt_get_tree(struct fs_context *fc)
 	struct rdt_resource *r;
 	int ret;
 
-	DO_ONCE_SLEEPABLE(resctrl_arch_pre_mount);
+	mutex_lock(&resctrl_mount_lock);
 
-	cpus_read_lock();
-	mutex_lock(&rdtgroup_mutex);
 	/*
 	 * resctrl file system can only be mounted once.
 	 */
 	if (resctrl_mounted) {
 		ret = -EBUSY;
-		goto out;
+		goto out_mount_unlock;
 	}
 
 	/* Avoid races from pending operations from a previous mount */
 	if (atomic_read(&rdtgroup_default.waitcount) != 0) {
 		ret = -EBUSY;
-		goto out;
+		goto out_mount_unlock;
 	}
 
+	resctrl_arch_pre_mount();
+
+	cpus_read_lock();
+	mutex_lock(&rdtgroup_mutex);
+
 	if (!resctrl_alloc_capable() && !resctrl_mon_capable()) {
 		ret = invalfc(fc, "No allocation or monitoring features are available or enabled");
 		goto out;
@@ -3287,6 +3299,8 @@ static int rdt_get_tree(struct fs_context *fc)
 	mutex_unlock(&rdtgroup_mutex);
 	cpus_read_unlock();
 
+	mutex_unlock(&resctrl_mount_lock);
+
 	ret = kernfs_get_tree(fc);
 	/*
 	 * resctrl can only be mounted once, new superblock only expected
@@ -3318,6 +3332,10 @@ static int rdt_get_tree(struct fs_context *fc)
 out:
 	mutex_unlock(&rdtgroup_mutex);
 	cpus_read_unlock();
+	resctrl_arch_unmount();
+out_mount_unlock:
+	mutex_unlock(&resctrl_mount_lock);
+
 	return ret;
 }
 
-- 
2.56.0

[PATCH v14 19/24] x86/resctrl: Enforce system RMID limit on AET

[Tony Luck]

The RMID a CPU uses for telemetry is the RMID written to
MSR_IA32_PQR_ASSOC.RMID, so the number of RMIDs that register can hold
(enumerated via CPUID) bounds every monitoring resource. Each AET
(Application Energy Telemetry) event group separately describes how many
RMIDs its counters support.

The number of RMIDs an event group supports may be higher than the number
that can be written to MSR_IA32_PQR_ASSOC.RMID. The telemetry resource
then advertises more RMIDs than can ever be used, both to user space in
info/PERF_PKG_MON/num_rmids and, on systems where telemetry is the only
monitoring resource, as the number of RMIDs available to the mount.

Cap the number of RMIDs of the telemetry resource at the number that can
be written to MSR_IA32_PQR_ASSOC.RMID.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	New commit comment
---
 arch/x86/kernel/cpu/resctrl/internal.h  | 2 ++
 arch/x86/kernel/cpu/resctrl/core.c      | 2 +-
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 6 ++++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c66954bc01e7..1f080aad1b67 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -153,6 +153,8 @@ extern struct rdt_hw_resource rdt_resources_all[];
 
 extern bool intel_rdt_mbm_need_quirk;
 
+extern u32 pqr_assoc_num_rmid;
+
 void arch_mon_domain_online(struct rdt_resource *r, struct rdt_l3_mon_domain *d);
 
 /* CPUID.(EAX=10H, ECX=ResID=1).EAX */
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 40466f29e48e..689b9e31fe7a 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -46,7 +46,7 @@ static DEFINE_MUTEX(domain_list_lock);
 DEFINE_PER_CPU(struct resctrl_pqr_state, pqr_state);
 
 /* Number of unique RMID values that can be written to MSR_IA32_PQR_ASSOC.RMID */
-static u32 pqr_assoc_num_rmid;
+u32 pqr_assoc_num_rmid;
 
 static void mba_wrmsr_intel(struct msr_param *m);
 static void cat_wrmsr(struct msr_param *m);
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 75cd602d65ae..5c88236d850f 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -308,6 +308,12 @@ static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
 	else
 		r->mon.num_rmid = e->num_rmid;
 
+	/*
+	 * AET may claim to support more RMIDs than are permitted to be
+	 * assigned to MSR_IA32_PQR_ASSOC.RMID. Enforce this limit.
+	 */
+	r->mon.num_rmid = min(r->mon.num_rmid, pqr_assoc_num_rmid);
+
 	if (skipped_events)
 		pr_info("%s %s:0x%x monitoring detected (skipped %d events)\n", r->name,
 			e->pfname, e->guid, skipped_events);
-- 
2.56.0

[PATCH v14 20/24] x86/resctrl: Export interface to report telemetry unbind/remove

[Tony Luck]

resctrl obtains the addresses of the telemetry MMIO regions from the
pmt_telemetry driver at mount time and holds a reference on the module
until unmount, so the module cannot be unloaded while resctrl may read
the counters.

The module reference does not prevent a telemetry device from being
unbound from the driver, or removed. Either tears down the MMIO mappings
that hold the event counters, and a subsequent read of an event by
resctrl faults on the stale address.

Provide an interface for pmt_telemetry to report that the mappings for a
package are about to be torn down. Stop using the regions of that package
and serialize event reads with the notification so that no read uses an
address once it has been reported. Events of the affected package then
read "Unavailable".

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Dropped aet_mmio_lock. Now safe to use aet_lock.
	New commit message
	Add code comment noting that per-package may be over-reaction.
---
 include/linux/intel_vsec.h              |  2 ++
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 30 +++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
index c04b1d0f3143..bcbf4937c71c 100644
--- a/include/linux/intel_vsec.h
+++ b/include/linux/intel_vsec.h
@@ -262,11 +262,13 @@ void intel_aet_register_enumeration(struct module *module,
 				    struct pmt_feature_group *(*get)(enum pmt_feature_id id),
 				    void (*put)(struct pmt_feature_group *p));
 void intel_aet_unregister_enumeration(void);
+void intel_aet_invalidate(u8 package_id);
 #else
 static inline void intel_aet_register_enumeration(struct module *module,
 						  struct pmt_feature_group *(*get)(enum pmt_feature_id id),
 						  void (*put)(struct pmt_feature_group *p)) { }
 static inline void intel_aet_unregister_enumeration(void) { }
+static inline void intel_aet_invalidate(u8 package_id) { }
 #endif /* CONFIG_X86_CPU_RESCTRL_INTEL_AET */
 
 #endif
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 5c88236d850f..3facb852f22b 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -339,6 +339,7 @@ static enum pmt_feature_id lookup_pfid(const char *pfname)
  * Serialises AET's view of pmt_telemetry:
  *   - pmt_module, get_feature, put_feature, pmt_in_use
  *   - every event_group's ->pfg
+ *   - the telemetry_region::addr entries reachable through ->pfg
  *
  * Lock ordering with pmt/telemetry.c's ep_lock is ep_lock -> aet_lock.
  * AET therefore must not call get_feature() (which takes ep_lock) while
@@ -413,6 +414,33 @@ void intel_aet_unregister_enumeration(void)
 }
 EXPORT_SYMBOL_NS_GPL(intel_aet_unregister_enumeration, "INTEL_PMT");
 
+/*
+ * pmt_telemetry driver calls while holding ep_lock. This is for unbind/remove
+ * operations that will invalidate the virtual addresses of MMIO registers
+ * provided by intel_pmt_get_regions_by_feature(). This simple interface may
+ * be overly broad if there are multiple telemetry devices per-package. An
+ * unbind/remove operation on one device will stop resctrl from reading
+ * event counters from all devices on the same package.
+ */
+void intel_aet_invalidate(u8 package_id)
+{
+	struct event_group **peg;
+
+	guard(mutex)(&aet_lock);
+
+	for_each_event_group(peg) {
+		struct event_group *e = *peg;
+
+		if (!e->pfg)
+			continue;
+		for (int i = 0; i < e->pfg->count; i++) {
+			if (e->pfg->regions[i].plat_info.package_id == package_id)
+				e->pfg->regions[i].addr = NULL;
+		}
+	}
+}
+EXPORT_SYMBOL_NS_GPL(intel_aet_invalidate, "INTEL_PMT");
+
 bool intel_aet_pre_mount(void)
 {
 	struct pmt_feature_group *(*get)(enum pmt_feature_id id);
@@ -488,6 +516,8 @@ int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
 	void *pevt0;
 	u32 idx;
 
+	guard(mutex)(&aet_lock);
+
 	pevt0 = pevt - pevt->idx;
 	e = container_of(pevt0, struct event_group, evts);
 	idx = rmid * e->num_events;
-- 
2.56.0

[PATCH v14 21/24] platform/x86/intel/pmt: Inform resctrl when MMIO maps are being removed

[Tony Luck]

resctrl obtains the virtual addresses of the telemetry MMIO regions from
intel_pmt_get_regions_by_feature() at mount time and reads event counters
from them until unmount.

When a telemetry device is unbound from the pmt_telemetry driver or
removed, the driver tears down those mappings. A subsequent read of a
telemetry event by resctrl faults on the stale address.

Before destroying the devices, tell resctrl that the mappings of the
device's package are about to be torn down and must not be used again.
Telemetry regions are organised per package, so the package ID identifies
the regions resctrl has to drop. This may be overly broad if there are
multiple telemetry devices on a package.

Notify resctrl while holding ep_lock so that the notification is ordered
against concurrent lookups of the regions. This is safe because ep_lock
is always taken before aet_lock.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Added commit comment on lock order.
	New commit comment.
---
 drivers/platform/x86/intel/pmt/telemetry.c | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/platform/x86/intel/pmt/telemetry.c b/drivers/platform/x86/intel/pmt/telemetry.c
index 57eb2967a4d0..bd63653802d9 100644
--- a/drivers/platform/x86/intel/pmt/telemetry.c
+++ b/drivers/platform/x86/intel/pmt/telemetry.c
@@ -366,12 +366,42 @@ pmt_telem_find_and_register_endpoint(struct device *dev, u32 guid, u16 pos)
 }
 EXPORT_SYMBOL_NS_GPL(pmt_telem_find_and_register_endpoint, "INTEL_PMT_TELEMETRY");
 
+static int pmt_telem_get_package_id(struct pmt_telem_priv *priv)
+{
+	int i;
+
+	for (i = 0; i < priv->num_entries; i++) {
+		struct intel_pmt_entry *entry = &priv->entry[i];
+		struct pci_dev *pdev = to_pci_dev(entry->ep->dev);
+		struct oobmsm_plat_info *plat_info;
+
+		plat_info = intel_vsec_get_mapping(pdev);
+		if (!IS_ERR(plat_info)) {
+			/* All entries for a device have the same package ID */
+			return plat_info->package_id;
+		}
+	}
+
+	return -ENODEV;
+}
+
 static void pmt_telem_remove(struct auxiliary_device *auxdev)
 {
 	struct pmt_telem_priv *priv = auxiliary_get_drvdata(auxdev);
+	int package_id;
 	int i;
 
 	mutex_lock(&ep_lock);
+	package_id = pmt_telem_get_package_id(priv);
+	/*
+	 * Tell resctrl/AET that virtual mappings for MMIO space in a CPU
+	 * package are about to be torn down.
+	 */
+	if (package_id < 0)
+		dev_dbg(&auxdev->dev, "Unable to determine package ID for removed device\n");
+	else
+		intel_aet_invalidate(package_id);
+
 	for (i = 0; i < priv->num_entries; i++) {
 		struct intel_pmt_entry *entry = &priv->entry[i];
 
-- 
2.56.0

[PATCH v14 22/24] x86/resctrl: Require 64-bit x86 for resctrl support

[Tony Luck]

Intel Application Energy Telemetry (AET) provides event counts in 64-bit
MMIO registers. For accurate results these must be read with a single
64-bit load, which is only available to 64-bit kernels, so AET support
depends on X86_64.

AET is about to become an unconditional part of x86 resctrl instead of
being selected by the separate CONFIG_X86_CPU_RESCTRL_INTEL_AET option.
resctrl can then no longer be built for 32-bit kernels.

Make resctrl depend on X86_64, in preparation for removing
CONFIG_X86_CPU_RESCTRL_INTEL_AET. This drops resctrl support from 32-bit
kernels, in line with Dave Hansen's proposal [1] to document reduced
support for 32-bit x86. Keeping support for 32-bit kernels is not
worth it. Modern systems that support resctrl almost always have more
memory than can be addressed by a 32-bit Linux kernel.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/all/c6ab0c24-8931-4f0d-9be6-23498ab4c38b@intel.com/ # [1]
---
v14:
	New commit message.
---
 arch/x86/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 15fd9ec5ecac..06b5d0c4633e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -518,7 +518,7 @@ config X86_MPPARSE
 
 config X86_CPU_RESCTRL
 	bool "x86 CPU resource control support"
-	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
+	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
 	depends on MISC_FILESYSTEMS
 	select ARCH_HAS_CPU_RESCTRL
 	select RESCTRL_FS
@@ -541,7 +541,7 @@ config X86_CPU_RESCTRL
 
 config X86_CPU_RESCTRL_INTEL_AET
 	bool "Intel Application Energy Telemetry"
-	depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
+	depends on X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
 	help
 	  Enable per-RMID telemetry events in resctrl.
 
-- 
2.56.0

[PATCH v14 23/24] x86/resctrl: Simplify Kconfig options for resctrl

[Tony Luck]

Application Energy Telemetry (AET) support in resctrl is selected by
CONFIG_X86_CPU_RESCTRL_INTEL_AET, which requires the pmt_telemetry and
TPMI drivers to be built in. Kernels that build those drivers as modules,
as distributions commonly do, cannot enable AET, and enabling it forces
the drivers to be built in.

resctrl now obtains the telemetry enumeration functions from
pmt_telemetry when that module loads and enumerates AET on every mount,
so the built-in requirement is no longer needed. Keeping a separate
option with relaxed dependencies would still add to the Kconfig
complexity that Linus Torvalds objected to [1].

Drop CONFIG_X86_CPU_RESCTRL_INTEL_AET and always build AET support as
part of x86 resctrl. AET remains inactive unless the pmt_telemetry driver
registers with resctrl.

With AET no longer an optional Intel-specific component, rename its
x86-internal functions from the intel_ prefix to the rdt_ prefix used by
the other functions in internal.h. The functions exported to
pmt_telemetry keep their names.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/all/CAHk-=whigg3hvOy7c1j1MXFy6o6CHp0g4Tc3Y-MAk+XDssHU0A@mail.gmail.com # [1]
---
v14:
	New commit message.
---
 include/linux/intel_vsec.h              |  4 ++--
 arch/x86/kernel/cpu/resctrl/internal.h  | 25 ++++++-------------------
 arch/x86/kernel/cpu/resctrl/core.c      |  8 ++++----
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 14 +++++++-------
 arch/x86/kernel/cpu/resctrl/monitor.c   |  2 +-
 arch/x86/Kconfig                        | 13 -------------
 arch/x86/kernel/cpu/resctrl/Makefile    |  3 +--
 7 files changed, 21 insertions(+), 48 deletions(-)

diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
index bcbf4937c71c..885f8e3ab057 100644
--- a/include/linux/intel_vsec.h
+++ b/include/linux/intel_vsec.h
@@ -257,7 +257,7 @@ static inline void
 intel_pmt_put_feature_group(struct pmt_feature_group *feature_group) {}
 #endif
 
-#ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET
+#ifdef CONFIG_X86_CPU_RESCTRL
 void intel_aet_register_enumeration(struct module *module,
 				    struct pmt_feature_group *(*get)(enum pmt_feature_id id),
 				    void (*put)(struct pmt_feature_group *p));
@@ -269,6 +269,6 @@ static inline void intel_aet_register_enumeration(struct module *module,
 						  void (*put)(struct pmt_feature_group *p)) { }
 static inline void intel_aet_unregister_enumeration(void) { }
 static inline void intel_aet_invalidate(u8 package_id) { }
-#endif /* CONFIG_X86_CPU_RESCTRL_INTEL_AET */
+#endif /* CONFIG_X86_CPU_RESCTRL */
 
 #endif
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 1f080aad1b67..10432f51949a 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -235,24 +235,11 @@ bool rdt_cpu_has(int flag);
 void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
 void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r);
 
-#ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET
-bool intel_aet_pre_mount(void);
-void intel_aet_unmount(void);
-int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
-void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
-				struct list_head *add_pos);
-bool intel_handle_aet_option(bool force_off, char *tok);
-#else
-static inline bool intel_aet_pre_mount(void) { return false; }
-static inline void intel_aet_unmount(void) { }
-static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
-{
-	return -EINVAL;
-}
-
-static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
-					      struct list_head *add_pos) { }
-static inline bool intel_handle_aet_option(bool force_off, char *tok) { return false; }
-#endif
+bool rdt_aet_pre_mount(void);
+void rdt_aet_unmount(void);
+int rdt_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
+void rdt_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
+			      struct list_head *add_pos);
+bool rdt_handle_aet_option(bool force_off, char *tok);
 
 #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 689b9e31fe7a..78cb1e8cd747 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -616,7 +616,7 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
 		break;
 	case RDT_RESOURCE_PERF_PKG:
 		if (!hdr)
-			intel_aet_mon_domain_setup(cpu, id, r, add_pos);
+			rdt_aet_mon_domain_setup(cpu, id, r, add_pos);
 		break;
 	default:
 		pr_warn_once("Unknown resource rid=%d\n", r->rid);
@@ -795,7 +795,7 @@ void resctrl_arch_pre_mount(void)
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
 	int cpu;
 
-	if (!intel_aet_pre_mount())
+	if (!rdt_aet_pre_mount())
 		return;
 
 	/*
@@ -819,7 +819,7 @@ void resctrl_arch_unmount(void)
 	if (!r->mon_capable)
 		return;
 
-	intel_aet_unmount();
+	rdt_aet_unmount();
 
 	cpus_read_lock();
 	mutex_lock(&domain_list_lock);
@@ -885,7 +885,7 @@ static int __init set_rdt_options(char *str)
 		force_off = *tok == '!';
 		if (force_off)
 			tok++;
-		if (intel_handle_aet_option(force_off, tok))
+		if (rdt_handle_aet_option(force_off, tok))
 			continue;
 		for (o = rdt_options; o < &rdt_options[NUM_RDT_OPTIONS]; o++) {
 			if (strcmp(tok, o->name) == 0) {
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 3facb852f22b..49e2caed6f45 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -173,7 +173,7 @@ static struct event_group *known_event_groups[] = {
 	     _peg < &known_event_groups[ARRAY_SIZE(known_event_groups)];	\
 	     _peg++)
 
-bool intel_handle_aet_option(bool force_off, char *tok)
+bool rdt_handle_aet_option(bool force_off, char *tok)
 {
 	struct event_group **peg;
 	bool ret = false;
@@ -228,7 +228,7 @@ static bool group_has_usable_regions(struct event_group *e, struct pmt_feature_g
 		if (skip_telem_region(&p->regions[i], e)) {
 			/*
 			 * Clear the address field of regions that did not pass the checks in
-			 * skip_telem_region() so they will not be used by intel_aet_read_event().
+			 * skip_telem_region() so they will not be used by rdt_aet_read_event().
 			 * This is safe to do because intel_pmt_get_regions_by_feature() allocates
 			 * a new pmt_feature_group structure to return to each caller and only makes
 			 * use of the pmt_feature_group::kref field when intel_pmt_put_feature_group()
@@ -441,7 +441,7 @@ void intel_aet_invalidate(u8 package_id)
 }
 EXPORT_SYMBOL_NS_GPL(intel_aet_invalidate, "INTEL_PMT");
 
-bool intel_aet_pre_mount(void)
+bool rdt_aet_pre_mount(void)
 {
 	struct pmt_feature_group *(*get)(enum pmt_feature_id id);
 	void (*put)(struct pmt_feature_group *p);
@@ -473,7 +473,7 @@ bool intel_aet_pre_mount(void)
 	return true;
 }
 
-void intel_aet_unmount(void)
+void rdt_aet_unmount(void)
 {
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
 	struct event_group **peg;
@@ -506,7 +506,7 @@ void intel_aet_unmount(void)
  * the MMIO read indicates that data is not valid.  Return success if at
  * least one aggregator has valid data.
  */
-int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
+int rdt_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
 {
 	struct pmt_event *pevt = arch_priv;
 	struct event_group *e;
@@ -546,8 +546,8 @@ int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
 	return valid ? 0 : -EINVAL;
 }
 
-void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
-				struct list_head *add_pos)
+void rdt_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
+			      struct list_head *add_pos)
 {
 	struct rdt_perf_pkg_mon_domain *d;
 	int err;
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index bd45d72d1d05..0701ec3ef4e0 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -255,7 +255,7 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
 	resctrl_arch_rmid_read_context_check();
 
 	if (r->rid == RDT_RESOURCE_PERF_PKG)
-		return intel_aet_read_event(hdr->id, rmid, arch_priv, val);
+		return rdt_aet_read_event(hdr->id, rmid, arch_priv, val);
 
 	if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
 		return -EINVAL;
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 06b5d0c4633e..47f92613434e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -539,19 +539,6 @@ config X86_CPU_RESCTRL
 
 	  Say N if unsure.
 
-config X86_CPU_RESCTRL_INTEL_AET
-	bool "Intel Application Energy Telemetry"
-	depends on X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
-	help
-	  Enable per-RMID telemetry events in resctrl.
-
-	  Intel feature that collects per-RMID execution data
-	  about energy consumption, measure of frequency independent
-	  activity and other performance metrics. Data is aggregated
-	  per package.
-
-	  Say N if unsure.
-
 config X86_FRED
 	bool "Flexible Return and Event Delivery"
 	depends on X86_64
diff --git a/arch/x86/kernel/cpu/resctrl/Makefile b/arch/x86/kernel/cpu/resctrl/Makefile
index 273ddfa30836..9daf1c0abb80 100644
--- a/arch/x86/kernel/cpu/resctrl/Makefile
+++ b/arch/x86/kernel/cpu/resctrl/Makefile
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_X86_CPU_RESCTRL)		+= core.o rdtgroup.o monitor.o
-obj-$(CONFIG_X86_CPU_RESCTRL)		+= ctrlmondata.o
-obj-$(CONFIG_X86_CPU_RESCTRL_INTEL_AET)	+= intel_aet.o
+obj-$(CONFIG_X86_CPU_RESCTRL)		+= ctrlmondata.o intel_aet.o
 obj-$(CONFIG_RESCTRL_FS_PSEUDO_LOCK)	+= pseudo_lock.o
 
 # To allow define_trace.h's recursive include:
-- 
2.56.0

[PATCH v14 24/24] x86,fs/resctrl: Document telemetry mount timing caveat

[Tony Luck]

resctrl enumerates telemetry events each time it is mounted, using
functions that the pmt_telemetry driver registers when it loads. The
driver can be built as a module, which is typically loaded by udev during
boot.

An automatic mount of resctrl from /etc/fstab early in boot can run
before pmt_telemetry has loaded. Telemetry events are then not enabled
in that mount, with no indication why.

Document the race, how to avoid it by mounting resctrl after
pmt_telemetry has loaded, and that unmounting and mounting resctrl again
enables the telemetry events.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v14:
	Updated commit message. Include unmount/remount as solution
	if early mount did not include AET.
---
 Documentation/filesystems/resctrl.rst | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index b52795e03303..66ffb625aac0 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -629,7 +629,7 @@ When monitoring is enabled all MON groups will also contain:
 	each instance of an L3 cache. Each directory contains files for the enabled
 	L3 events (e.g. "llc_occupancy", "mbm_total_bytes", and "mbm_local_bytes").
 
-	If telemetry monitoring is enabled, there will be a "mon_PERF_PKG_YY"
+	If telemetry monitoring is enabled [#]_, there will be a "mon_PERF_PKG_YY"
 	directory for each physical processor package. Each directory contains
 	files for the enabled telemetry events (e.g. "core_energy". "activity",
 	"uops_retired", etc.)
@@ -668,6 +668,12 @@ When monitoring is enabled all MON groups will also contain:
 	returned if the MBM event does not have an assigned counter in the
 	CTRL_MON group nor in any of its associated MON groups.
 
+.. [#] Telemetry features are enumerated asynchronously by the PMT driver, so
+   an automatic mount of resctrl from ``/etc/fstab`` at boot may not enable
+   them. To avoid this race, defer the mount until after the ``pmt_telemetry``
+   module has loaded. Unmounting and remounting the resctrl file system will
+   fix the issue.
+
 "mon_hw_id":
 	Available only with debug option. The identifier used by hardware
 	for the monitor group. On x86 this is the RMID.
-- 
2.56.0

Re: [PATCH v14 09/24] fs/resctrl: Remove redundant calls to resctrl_mon_capable()

[Chen Yu]

Hi Tony,

On Mon, Oct 19, 2026 at 01:50:16PM -0700, Tony Luck wrote:
> resctrl_mon_capable() reports whether the system supports monitoring by
> scanning all resources. On x86 it used to read a single architecture-provided
> flag. Calls on paths that run repeatedly now pay for the scan.
> 
> Two such callers already know that monitoring is supported:
> 
> 1) mbm_handle_overflow()
> The MBM overflow handler runs once per second on each L3 monitoring
> domain. It is only set up when MBM events are enabled, which requires
> L3 monitoring support.
>

There is also a resctrl_mon_capable() check in mbm_setup_overflow_handler(),
do we need to remove it too?  But it is only called once in mbm_setup_overflow_handler(),
leave it as it is should be OK.

> 2) is_rmid_match()
> Called for every task in the system when walking the task list to read
> a tasks file, remove a group, or unmount. It only matches MON groups,
> which can only be created on a system that supports monitoring.
> 
> Remove the call to resctrl_mon_capable() from both functions.
>
> No functional change intended.
> 
> Signed-off-by: Tony Luck <tony.luck@intel.com>
>

Reviewed-by: Chen Yu <yu.c.chen@intel.com>

thanks,
Chenyu

Re: [PATCH v14 06/24] arm,x86,fs/resctrl: Replace architecture capability helpers with generic versions

[Chen Yu]

Hi Tony,

On Mon, Oct 19, 2026 at 01:50:13PM -0700, Tony Luck wrote:
> resctrl supports allocation or monitoring if any resource is capable of
> it. Each architecture answers this via resctrl_arch_alloc_capable() and
> resctrl_arch_mon_capable(). x86 maintains global flags for this in
> addition to the per-resource flags and must keep both in sync. MPAM
> derives the answer from its per-resource flags.
> 
> The per-resource flags are part of the resource description that the file
> system already has, so the architecture helpers duplicate information
> available to the file system.
> 
> Define resctrl_alloc_capable() and resctrl_mon_capable() in the file system
> based on the per-resource flags and remove the architecture helpers, in
> preparation for removing the x86 global flags. The result is unchanged for
> MPAM, which presents all monitors on the L3 resource.
> 
> Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
>

Since this possible regress window is very small, and I did not find any issue
in this change,

Reviewed-by: Chen Yu <yu.c.chen@intel.com>

thanks,
Chenyu

Re: [PATCH v14 10/24] x86/resctrl: Honor rdt={perf|energy} options to force enable AET events

[Chen Yu]

On Mon, Oct 19, 2026 at 01:50:17PM -0700, Tony Luck wrote:
> resctrl can disable a feature the platform supports, for example because
> of an erratum or, for Application Energy Telemetry (AET), because an event
> group has insufficient RMIDs. The "rdt=" kernel command line option lets
> the user force such a feature on anyway, and also lets the user disable
> supported features they do not need.
> 
> resctrl enumerates AET once, on first mount. Enumeration skips an event
> group that is marked disabled. An event group with insufficient RMIDs is
> marked disabled even when the user forced it on, but this happens after
> the test for forced off when enumeration begins for an event group.
> 
> This will be broken when AET is enumerated on every mount. The disable mark
> recorded for insufficient RMIDs on one mount causes the event group to be
> skipped on the next, ignoring the user's explicit rdt= request to enable it.
> 
> In preparation for enumerating AET on every mount, skip a disabled event
> group only if the user has not forced it on. As a result, when the command
> line both disables and enables the same event group, for example
> "rdt=!perf,perf:<guid>", enabling now takes precedence. This matches how
> rdt= handles the other resctrl features.
> 
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
> v14:
> 	New commit message. Dropped previous supplied Reinette RB tag.
> ---
>  arch/x86/kernel/cpu/resctrl/intel_aet.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index 66cd8c2c7a51..9f0829a82cb0 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -262,7 +262,7 @@ static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
>  	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
>  	int skipped_events = 0;
>  
> -	if (e->force_off)
> +	if (e->force_off && !e->force_on)
>  		return false;
>

OK, it seems that the user always has the highest priority in deciding whether
this event is enabled, which overrides the hardware/kernel decision. This will also
be the design for region aware MBA's erdt:3waymba. Per my understanding,

Reviewed-by: Chen Yu <yu.c.chen@intel.com>

thanks,
Chenyu

>  	if (!group_has_usable_regions(e, p))
> -- 
> 2.56.0
> 

Re: [PATCH v14 09/24] fs/resctrl: Remove redundant calls to resctrl_mon_capable()

[Luck, Tony]

Hi Chenyu,

On Tue, Oct 20, 2026 at 09:38:41PM +0800, Chen Yu wrote:
> Hi Tony,
> 
> On Mon, Oct 19, 2026 at 01:50:16PM -0700, Tony Luck wrote:
> > resctrl_mon_capable() reports whether the system supports monitoring by
> > scanning all resources. On x86 it used to read a single architecture-provided
> > flag. Calls on paths that run repeatedly now pay for the scan.
> > 
> > Two such callers already know that monitoring is supported:
> > 
> > 1) mbm_handle_overflow()
> > The MBM overflow handler runs once per second on each L3 monitoring
> > domain. It is only set up when MBM events are enabled, which requires
> > L3 monitoring support.
> >
> 
> There is also a resctrl_mon_capable() check in mbm_setup_overflow_handler(),
> do we need to remove it too?  But it is only called once in mbm_setup_overflow_handler(),
> leave it as it is should be OK.

Yes. I was only worried about calls in hot code paths. This call can
happen more than once if CPU hotplug removes and adds a domain. But
that's still not a hot code path.

> 
> > 2) is_rmid_match()
> > Called for every task in the system when walking the task list to read
> > a tasks file, remove a group, or unmount. It only matches MON groups,
> > which can only be created on a system that supports monitoring.
> > 
> > Remove the call to resctrl_mon_capable() from both functions.
> >
> > No functional change intended.
> > 
> > Signed-off-by: Tony Luck <tony.luck@intel.com>
> >
> 
> Reviewed-by: Chen Yu <yu.c.chen@intel.com>

Thanks for the review.

> 
> thanks,
> Chenyu

-Tony