[PATCH stable 6.3 0/4] Missing cacheinfo backports

[PATCH stable 6.3 0/4] Missing cacheinfo backports

[Florian Fainelli]

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These patches resolve the following errors seen with linux-6.3.y on our
ARCH_BRCMSTB platforms which contain cache information in the Device
Tree:

[    0.002072] Early cacheinfo failed, ret = -22

Pierre Gondois (1):
  cacheinfo: Add use_arch[|_cache]_info field/function

Radu Rendec (3):
  cacheinfo: Add arch specific early level initializer
  cacheinfo: Add arm64 early level initializer implementation
  cacheinfo: Allow early level detection when DT/ACPI info is
    missing/broken

 arch/arm64/kernel/cacheinfo.c | 25 ++++++++--
 drivers/base/arch_topology.c  |  4 +-
 drivers/base/cacheinfo.c      | 87 +++++++++++++++++++++++++----------
 include/linux/cacheinfo.h     |  8 ++++
 4 files changed, 95 insertions(+), 29 deletions(-)

-- 
2.25.1


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[PATCH stable 6.3 1/4] cacheinfo: Add use_arch[|_cache]_info field/function

[Florian Fainelli]

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From: Pierre Gondois <pierre.gondois@arm.com>

commit ef9f643a9f8b62bcbcc51f0e0af8599adc2e17ed upstream

The cache information can be extracted from either a Device
Tree (DT), the PPTT ACPI table, or arch registers (clidr_el1
for arm64).

The clidr_el1 register is used only if DT/ACPI information is not
available. It does not states how caches are shared among CPUs.

Add a use_arch_cache_info field/function to identify when the
DT/ACPI doesn't provide cache information. Use this information
to assume L1 caches are privates and L2 and higher are shared among
all CPUs.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/r/20230414081453.244787-5-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/base/cacheinfo.c  | 12 ++++++++++--
 include/linux/cacheinfo.h |  6 ++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index ea8f416852bd..8120ac1ddbe4 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -28,6 +28,9 @@ static DEFINE_PER_CPU(struct cpu_cacheinfo, ci_cpu_cacheinfo);
 #define per_cpu_cacheinfo_idx(cpu, idx)		\
 				(per_cpu_cacheinfo(cpu) + (idx))
 
+/* Set if no cache information is found in DT/ACPI. */
+static bool use_arch_info;
+
 struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu)
 {
 	return ci_cacheinfo(cpu);
@@ -40,7 +43,8 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
 	 * For non DT/ACPI systems, assume unique level 1 caches,
 	 * system-wide shared caches for all other levels.
 	 */
-	if (!(IS_ENABLED(CONFIG_OF) || IS_ENABLED(CONFIG_ACPI)))
+	if (!(IS_ENABLED(CONFIG_OF) || IS_ENABLED(CONFIG_ACPI)) ||
+	    use_arch_info)
 		return (this_leaf->level != 1) && (sib_leaf->level != 1);
 
 	if ((sib_leaf->attributes & CACHE_ID) &&
@@ -343,6 +347,10 @@ static int cache_setup_properties(unsigned int cpu)
 	else if (!acpi_disabled)
 		ret = cache_setup_acpi(cpu);
 
+	// Assume there is no cache information available in DT/ACPI from now.
+	if (ret && use_arch_cache_info())
+		use_arch_info = true;
+
 	return ret;
 }
 
@@ -361,7 +369,7 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
 	 * to update the shared cpu_map if the cache attributes were
 	 * populated early before all the cpus are brought online
 	 */
-	if (!last_level_cache_is_valid(cpu)) {
+	if (!last_level_cache_is_valid(cpu) && !use_arch_info) {
 		ret = cache_setup_properties(cpu);
 		if (ret)
 			return ret;
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 908e19d17f49..b91cc9991c7c 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -129,4 +129,10 @@ static inline int get_cpu_cacheinfo_id(int cpu, int level)
 	return -1;
 }
 
+#ifdef CONFIG_ARM64
+#define use_arch_cache_info()	(true)
+#else
+#define use_arch_cache_info()	(false)
+#endif
+
 #endif /* _LINUX_CACHEINFO_H */
-- 
2.25.1


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[PATCH stable 6.3 2/4] cacheinfo: Add arch specific early level initializer

[Florian Fainelli]

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From: Radu Rendec <rrendec@redhat.com>

commit 6539cffa94957241c096099a57d05fa4d8c7db8a upstream

This patch gives architecture specific code the ability to initialize
the cache level and allocate cacheinfo memory early, when cache level
initialization runs on the primary CPU for all possible CPUs.

This is part of a patch series that attempts to further the work in
commit 5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU").
Previously, in the absence of any DT/ACPI cache info, architecture
specific cache detection and info allocation for secondary CPUs would
happen in non-preemptible context during early CPU initialization and
trigger a "BUG: sleeping function called from invalid context" splat on
an RT kernel.

More specifically, this patch adds the early_cache_level() function,
which is called by fetch_cache_info() as a fallback when the number of
cache leaves cannot be extracted from DT/ACPI. In the default generic
(weak) implementation, this new function returns -ENOENT, which
preserves the original behavior for architectures that do not implement
the function.

Since early detection can get the number of cache leaves wrong in some
cases*, additional logic is added to still call init_cache_level() later
on the secondary CPU, therefore giving the architecture specific code an
opportunity to go back and fix the initial guess. Again, the original
behavior is preserved for architectures that do not implement the new
function.

* For example, on arm64, CLIDR_EL1 detection works only when it runs on
  the current CPU. In other words, a CPU cannot detect the cache depth
  for any other CPU than itself.

Signed-off-by: Radu Rendec <rrendec@redhat.com>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/r/20230412185759.755408-2-rrendec@redhat.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/base/cacheinfo.c  | 75 +++++++++++++++++++++++++++------------
 include/linux/cacheinfo.h |  2 ++
 2 files changed, 55 insertions(+), 22 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 8120ac1ddbe4..14aa62c3f10f 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -437,6 +437,11 @@ static void free_cache_attributes(unsigned int cpu)
 	cache_shared_cpu_map_remove(cpu);
 }
 
+int __weak early_cache_level(unsigned int cpu)
+{
+	return -ENOENT;
+}
+
 int __weak init_cache_level(unsigned int cpu)
 {
 	return -ENOENT;
@@ -462,56 +467,82 @@ int allocate_cache_info(int cpu)
 
 int fetch_cache_info(unsigned int cpu)
 {
-	struct cpu_cacheinfo *this_cpu_ci;
+	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 	unsigned int levels = 0, split_levels = 0;
 	int ret;
 
 	if (acpi_disabled) {
 		ret = init_of_cache_level(cpu);
-		if (ret < 0)
-			return ret;
 	} else {
 		ret = acpi_get_cache_info(cpu, &levels, &split_levels);
-		if (ret < 0)
+		if (!ret) {
+			this_cpu_ci->num_levels = levels;
+			/*
+			 * This assumes that:
+			 * - there cannot be any split caches (data/instruction)
+			 *   above a unified cache
+			 * - data/instruction caches come by pair
+			 */
+			this_cpu_ci->num_leaves = levels + split_levels;
+		}
+	}
+
+	if (ret || !cache_leaves(cpu)) {
+		ret = early_cache_level(cpu);
+		if (ret)
 			return ret;
 
-		this_cpu_ci = get_cpu_cacheinfo(cpu);
-		this_cpu_ci->num_levels = levels;
-		/*
-		 * This assumes that:
-		 * - there cannot be any split caches (data/instruction)
-		 *   above a unified cache
-		 * - data/instruction caches come by pair
-		 */
-		this_cpu_ci->num_leaves = levels + split_levels;
+		if (!cache_leaves(cpu))
+			return -ENOENT;
+
+		this_cpu_ci->early_ci_levels = true;
 	}
-	if (!cache_leaves(cpu))
-		return -ENOENT;
 
 	return allocate_cache_info(cpu);
 }
 
-int detect_cache_attributes(unsigned int cpu)
+static inline int init_level_allocate_ci(unsigned int cpu)
 {
-	int ret;
+	unsigned int early_leaves = cache_leaves(cpu);
 
 	/* Since early initialization/allocation of the cacheinfo is allowed
 	 * via fetch_cache_info() and this also gets called as CPU hotplug
 	 * callbacks via cacheinfo_cpu_online, the init/alloc can be skipped
 	 * as it will happen only once (the cacheinfo memory is never freed).
-	 * Just populate the cacheinfo.
+	 * Just populate the cacheinfo. However, if the cacheinfo has been
+	 * allocated early through the arch-specific early_cache_level() call,
+	 * there is a chance the info is wrong (this can happen on arm64). In
+	 * that case, call init_cache_level() anyway to give the arch-specific
+	 * code a chance to make things right.
 	 */
-	if (per_cpu_cacheinfo(cpu))
-		goto populate_leaves;
+	if (per_cpu_cacheinfo(cpu) && !ci_cacheinfo(cpu)->early_ci_levels)
+		return 0;
 
 	if (init_cache_level(cpu) || !cache_leaves(cpu))
 		return -ENOENT;
 
-	ret = allocate_cache_info(cpu);
+	/*
+	 * Now that we have properly initialized the cache level info, make
+	 * sure we don't try to do that again the next time we are called
+	 * (e.g. as CPU hotplug callbacks).
+	 */
+	ci_cacheinfo(cpu)->early_ci_levels = false;
+
+	if (cache_leaves(cpu) <= early_leaves)
+		return 0;
+
+	kfree(per_cpu_cacheinfo(cpu));
+	return allocate_cache_info(cpu);
+}
+
+int detect_cache_attributes(unsigned int cpu)
+{
+	int ret;
+
+	ret = init_level_allocate_ci(cpu);
 	if (ret)
 		return ret;
 
-populate_leaves:
 	/*
 	 * If LLC is valid the cache leaves were already populated so just go to
 	 * update the cpu map.
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index b91cc9991c7c..a5cfd44fab45 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -76,9 +76,11 @@ struct cpu_cacheinfo {
 	unsigned int num_levels;
 	unsigned int num_leaves;
 	bool cpu_map_populated;
+	bool early_ci_levels;
 };
 
 struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
+int early_cache_level(unsigned int cpu);
 int init_cache_level(unsigned int cpu);
 int init_of_cache_level(unsigned int cpu);
 int populate_cache_leaves(unsigned int cpu);
-- 
2.25.1


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[PATCH stable 6.3 3/4] cacheinfo: Add arm64 early level initializer implementation

[Florian Fainelli]

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From: Radu Rendec <rrendec@redhat.com>

commit c931680cfa958c8fe9ace31a1dbeefff75597d54 upstream

This patch adds an architecture specific early cache level detection
handler for arm64. This is basically the CLIDR_EL1 based detection that
was previously done (only) in init_cache_level().

This is part of a patch series that attempts to further the work in
commit 5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU").
Previously, in the absence of any DT/ACPI cache info, architecture
specific cache detection and info allocation for secondary CPUs would
happen in non-preemptible context during early CPU initialization and
trigger a "BUG: sleeping function called from invalid context" splat on
an RT kernel.

This patch does not solve the problem completely for RT kernels. It
relies on the assumption that on most systems, the CPUs are symmetrical
and therefore have the same number of cache leaves. The cacheinfo memory
is allocated early (on the primary CPU), relying on the new handler. If
later (when CLIDR_EL1 based detection runs again on the secondary CPU)
the initial assumption proves to be wrong and the CPU has in fact more
leaves, the cacheinfo memory is reallocated, and that still triggers a
splat on an RT kernel.

In other words, asymmetrical CPU systems *must* still provide cacheinfo
data in DT/ACPI to avoid the splat on RT kernels (unless secondary CPUs
happen to have less leaves than the primary CPU). But symmetrical CPU
systems (the majority) can now get away without the additional DT/ACPI
data and rely on CLIDR_EL1 based detection.

Signed-off-by: Radu Rendec <rrendec@redhat.com>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/r/20230412185759.755408-3-rrendec@redhat.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 arch/arm64/kernel/cacheinfo.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index c307f69e9b55..d9c9218fa1fd 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -38,11 +38,9 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
 	this_leaf->type = type;
 }
 
-int init_cache_level(unsigned int cpu)
+static void detect_cache_level(unsigned int *level_p, unsigned int *leaves_p)
 {
 	unsigned int ctype, level, leaves;
-	int fw_level, ret;
-	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 
 	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
 		ctype = get_cache_type(level);
@@ -54,6 +52,27 @@ int init_cache_level(unsigned int cpu)
 		leaves += (ctype == CACHE_TYPE_SEPARATE) ? 2 : 1;
 	}
 
+	*level_p = level;
+	*leaves_p = leaves;
+}
+
+int early_cache_level(unsigned int cpu)
+{
+	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
+
+	detect_cache_level(&this_cpu_ci->num_levels, &this_cpu_ci->num_leaves);
+
+	return 0;
+}
+
+int init_cache_level(unsigned int cpu)
+{
+	unsigned int level, leaves;
+	int fw_level, ret;
+	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
+
+	detect_cache_level(&level, &leaves);
+
 	if (acpi_disabled) {
 		fw_level = of_find_last_cache_level(cpu);
 	} else {
-- 
2.25.1


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[PATCH stable 6.3 4/4] cacheinfo: Allow early level detection when DT/ACPI info is missing/broken

[Florian Fainelli]

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From: Radu Rendec <rrendec@redhat.com>

commit e103d55465db06c5344201fd5fa11bb19bc479c5 upstream

Recent work enables cacheinfo memory for secondary CPUs to be allocated
early, while still running on the primary CPU. That allows cacheinfo
memory to be allocated safely on RT kernels. To make that work, the
number of cache levels/leaves must be defined in the device tree or ACPI
tables. Further work adds a path for early detection of the number of
cache levels/leaves, which makes it possible to allocate the cacheinfo
memory early without requiring extra DT/ACPI information.

This patch addresses a specific issue with ACPI systems with no PPTT. In
that case, parse_acpi_topology() returns an error code, which in turn
makes init_cpu_topology() return early, before fetch_cache_info() is
called. In that case, the early cache level detection doesn't run.

The solution is to simply remove the "return" statement and let the code
flow fall through to calling fetch_cache_info().

Signed-off-by: Radu Rendec <rrendec@redhat.com>
Reported-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/all/dea94484-797f-3034-7b86-6d88801c0d91@arm.com/
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/r/20230412185759.755408-4-rrendec@redhat.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/base/arch_topology.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index c4b6198d7461..b741b5ba82bd 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -835,10 +835,10 @@ void __init init_cpu_topology(void)
 	if (ret) {
 		/*
 		 * Discard anything that was parsed if we hit an error so we
-		 * don't use partial information.
+		 * don't use partial information. But do not return yet to give
+		 * arch-specific early cache level detection a chance to run.
 		 */
 		reset_cpu_topology();
-		return;
 	}
 
 	for_each_possible_cpu(cpu) {
-- 
2.25.1


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