[PATCH v6 02/18] x86/resctrl: Add PLZA support to command-line options

[Babu Moger <babu.moger@amd.com>]

Add a kernel command-line parameter to enable or disable the exposure of
the PLZA (Privilege Level Zero Association) feature to resctrl.

This allows administrators to control PLZA visibility at boot time via the
rdt= option (e.g. rdt=plza or rdt=!plza).

Add "plza" to the rdt= command-line parameter so PLZA exposure to resctrl
can be enabled or disabled at boot. PLZA is exposed by default when
supported; rdt=!plza suppresses it.

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v6: Updated the changelog.

v5: Updated the changelog to mention about rdt= options.

v4: Split the patch 1 from v3 into 2 patches.
    This patch contains changes for resctrl subsystem.
---
 Documentation/admin-guide/kernel-parameters.txt | 2 +-
 Documentation/filesystems/resctrl.rst           | 1 +
 arch/x86/kernel/cpu/resctrl/core.c              | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 33cd30996e47..ee39a39ee9cd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6449,7 +6449,7 @@ Kernel parameters
 	rdt=		[HW,X86,RDT]
 			Turn on/off individual RDT features. List is:
 			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
-			mba, smba, bmec, abmc, sdciae, energy[:guid],
+			mba, smba, bmec, abmc, sdciae, plza, energy[:guid],
 			perf[:guid].
 			E.g. to turn on cmt and turn off mba use:
 				rdt=cmt,!mba
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index dd4f80da419c..73bf89d0ac83 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -28,6 +28,7 @@ SMBA (Slow Memory Bandwidth Allocation)				""
 BMEC (Bandwidth Monitoring Event Configuration)			""
 ABMC (Assignable Bandwidth Monitoring Counters)			""
 SDCIAE (Smart Data Cache Injection Allocation Enforcement)	""
+PLZA (Privilege Level Zero Association)				""
 =============================================================== ================================
 
 Historically, new features were made visible by default in /proc/cpuinfo. This
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 55214d6fdc49..4ca8bedeb995 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -803,6 +803,7 @@ enum {
 	RDT_FLAG_BMEC,
 	RDT_FLAG_ABMC,
 	RDT_FLAG_SDCIAE,
+	RDT_FLAG_PLZA,
 };
 
 #define RDT_OPT(idx, n, f)	\
@@ -830,6 +831,7 @@ static struct rdt_options rdt_options[]  __ro_after_init = {
 	RDT_OPT(RDT_FLAG_BMEC,	    "bmec",	X86_FEATURE_BMEC),
 	RDT_OPT(RDT_FLAG_ABMC,	    "abmc",	X86_FEATURE_ABMC),
 	RDT_OPT(RDT_FLAG_SDCIAE,    "sdciae",	X86_FEATURE_SDCIAE),
+	RDT_OPT(RDT_FLAG_PLZA,	    "plza",	X86_FEATURE_PLZA),
 };
 #define NUM_RDT_OPTIONS ARRAY_SIZE(rdt_options)
 
-- 
2.43.0