[PATCH 0/5] arch_topology: Build cacheinfo from primary CPU

[PATCH 0/5] arch_topology: Build cacheinfo from primary CPU

[Pierre Gondois]

[1] and [2] build the CPU topology from the cacheinfo information for
both DT/ACPI based systems and remove (struct cpu_topology).llc_id
which was used by ACPI only.

Creating the cacheinfo for secondary CPUs is done during early boot.
Preemption and interrupts are disabled at this stage. On PREEMPT_RT
kernels, allocating memory (and parsing the PPTT table for ACPI based
systems) triggers a:
  'BUG: sleeping function called from invalid context' [4]

To prevent this bug, allocate the cacheinfo from the primary CPU when
preemption and interrupts are enabled and before booting secondary
CPUs. The cache levels/leaves are computed from DT/ACPI PPTT information
only, without relying on the arm64 CLIDR_EL1 register.
If no cache information is found in the DT/ACPI PPTT, then fallback
to the current state, triggering [4] on PREEMPT_RT kernels.

Patches to update the arm64 device trees that have incomplete cacheinfo
(mostly for missing the 'cache-level' or 'cache-unified' property)
have been sent at [3].

Tested platforms:
- ACPI + PPTT: Ampere Altra, Ampere eMAG, Cavium ThunderX2,
  Kunpeng 920, Juno-r2
- DT: rb5, db845c, Juno-r2

[1] https://lore.kernel.org/all/20220704101605.1318280-1-sudeep.holla@arm.com/
[2] https://lore.kernel.org/all/20220720-arch_topo_fixes-v3-0-43d696288e84@arm.com/
[3] https://lore.kernel.org/all/20221107155825.1644604-1-pierre.gondois@arm.com/
[4] On an Ampere Altra, with PREEMPT_RT kernel based on v6.0.0-rc4:


[    7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
[    7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
[    7.560796] preempt_count: 1, expected: 0
[    7.560797] RCU nest depth: 1, expected: 1
[    7.560799] 3 locks held by swapper/111/0:
[    7.560800]  #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
[    7.560811]  #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
[    7.560820]  #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
[    7.560824] irq event stamp: 0
[    7.560825] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
[    7.560827] hardirqs last disabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
[    7.560830] softirqs last  enabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
[    7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0
[    7.560834] Preemption disabled at:
[    7.560835] [<ffffc5f8e9fd3c28>] migrate_enable+0x30/0x130
[    7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-[...]
[    7.560841] Call trace:
[...]
[    7.560870]  __kmalloc+0xbc/0x1e8
[    7.560873]  detect_cache_attributes+0x2d4/0x5f0
[    7.560876]  update_siblings_masks+0x30/0x368
[    7.560880]  store_cpu_topology+0x78/0xb8
[    7.560883]  secondary_start_kernel+0xd0/0x198
[    7.560885]  __secondary_switched+0xb0/0xb4

Pierre Gondois (5):
  cacheinfo: Use riscv's init_cache_level() as generic OF implem
  cacheinfo: Return error code in init_of_cache_level()
  ACPI: PPTT: Remove acpi_find_cache_levels()
  ACPI: PPTT: Update acpi_find_last_cache_level() to
    acpi_get_cache_info()
  arch_topology: Build cacheinfo from primary CPU

 arch/arm64/kernel/cacheinfo.c |   9 ++-
 arch/riscv/kernel/cacheinfo.c |  39 +------------
 drivers/acpi/pptt.c           |  86 +++++++++++++++++------------
 drivers/base/arch_topology.c  |  10 +++-
 drivers/base/cacheinfo.c      | 101 ++++++++++++++++++++++++++++++----
 include/linux/cacheinfo.h     |  10 +++-
 6 files changed, 164 insertions(+), 91 deletions(-)

-- 
2.25.1


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[PATCH 1/5] cacheinfo: Use riscv's init_cache_level() as generic OF implem

[Pierre Gondois]

Riscv's implementation of init_of_cache_level() is following
the Devicetree Specification v0.3 regarding caches, cf.:
- s3.7.3 'Internal (L1) Cache Properties'
- s3.8 'Multi-level and Shared Cache Nodes'

Allow reusing the implementation by moving it.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
 arch/riscv/kernel/cacheinfo.c | 39 +------------------------------
 drivers/base/cacheinfo.c      | 44 +++++++++++++++++++++++++++++++++++
 include/linux/cacheinfo.h     |  1 +
 3 files changed, 46 insertions(+), 38 deletions(-)

diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index 90deabfe63ea..440a3df5944c 100644
--- a/arch/riscv/kernel/cacheinfo.c
+++ b/arch/riscv/kernel/cacheinfo.c
@@ -115,44 +115,7 @@ static void fill_cacheinfo(struct cacheinfo **this_leaf,
 
 int init_cache_level(unsigned int cpu)
 {
-	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
-	struct device_node *np = of_cpu_device_node_get(cpu);
-	struct device_node *prev = NULL;
-	int levels = 0, leaves = 0, level;
-
-	if (of_property_read_bool(np, "cache-size"))
-		++leaves;
-	if (of_property_read_bool(np, "i-cache-size"))
-		++leaves;
-	if (of_property_read_bool(np, "d-cache-size"))
-		++leaves;
-	if (leaves > 0)
-		levels = 1;
-
-	prev = np;
-	while ((np = of_find_next_cache_node(np))) {
-		of_node_put(prev);
-		prev = np;
-		if (!of_device_is_compatible(np, "cache"))
-			break;
-		if (of_property_read_u32(np, "cache-level", &level))
-			break;
-		if (level <= levels)
-			break;
-		if (of_property_read_bool(np, "cache-size"))
-			++leaves;
-		if (of_property_read_bool(np, "i-cache-size"))
-			++leaves;
-		if (of_property_read_bool(np, "d-cache-size"))
-			++leaves;
-		levels = level;
-	}
-
-	of_node_put(np);
-	this_cpu_ci->num_levels = levels;
-	this_cpu_ci->num_leaves = leaves;
-
-	return 0;
+	return init_of_cache_level(cpu);
 }
 
 int populate_cache_leaves(unsigned int cpu)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 4b5cd08c5a65..a4308b48dd3e 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -224,8 +224,52 @@ static int cache_setup_of_node(unsigned int cpu)
 
 	return 0;
 }
+
+int init_of_cache_level(unsigned int cpu)
+{
+	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
+	struct device_node *np = of_cpu_device_node_get(cpu);
+	struct device_node *prev = NULL;
+	int levels = 0, leaves = 0, level;
+
+	if (of_property_read_bool(np, "cache-size"))
+		++leaves;
+	if (of_property_read_bool(np, "i-cache-size"))
+		++leaves;
+	if (of_property_read_bool(np, "d-cache-size"))
+		++leaves;
+	if (leaves > 0)
+		levels = 1;
+
+	prev = np;
+	while ((np = of_find_next_cache_node(np))) {
+		of_node_put(prev);
+		prev = np;
+		if (!of_device_is_compatible(np, "cache"))
+			break;
+		if (of_property_read_u32(np, "cache-level", &level))
+			break;
+		if (level <= levels)
+			break;
+		if (of_property_read_bool(np, "cache-size"))
+			++leaves;
+		if (of_property_read_bool(np, "i-cache-size"))
+			++leaves;
+		if (of_property_read_bool(np, "d-cache-size"))
+			++leaves;
+		levels = level;
+	}
+
+	of_node_put(np);
+	this_cpu_ci->num_levels = levels;
+	this_cpu_ci->num_leaves = leaves;
+
+	return 0;
+}
+
 #else
 static inline int cache_setup_of_node(unsigned int cpu) { return 0; }
+int init_of_cache_level(unsigned int cpu) { return 0; }
 #endif
 
 int __weak cache_setup_acpi(unsigned int cpu)
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 00b7a6ae8617..ff0328f3fbb0 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -80,6 +80,7 @@ struct cpu_cacheinfo {
 
 struct cpu_cacheinfo *get_cpu_cacheinfo(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);
 int cache_setup_acpi(unsigned int cpu);
 bool last_level_cache_is_valid(unsigned int cpu);
-- 
2.25.1


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[PATCH 2/5] cacheinfo: Return error code in init_of_cache_level()

[Pierre Gondois]

Make init_of_cache_level() return an error code when the cache
information parsing fails to help detecting missing information.

init_of_cache_level() is only called for riscv. Returning an error
code instead of 0 will prevent detect_cache_attributes() to allocate
memory if an incomplete DT is parsed.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
 drivers/base/cacheinfo.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index a4308b48dd3e..6f6cd120c4f1 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -246,11 +246,11 @@ int init_of_cache_level(unsigned int cpu)
 		of_node_put(prev);
 		prev = np;
 		if (!of_device_is_compatible(np, "cache"))
-			break;
+			goto err_out;
 		if (of_property_read_u32(np, "cache-level", &level))
-			break;
+			goto err_out;
 		if (level <= levels)
-			break;
+			goto err_out;
 		if (of_property_read_bool(np, "cache-size"))
 			++leaves;
 		if (of_property_read_bool(np, "i-cache-size"))
@@ -265,6 +265,10 @@ int init_of_cache_level(unsigned int cpu)
 	this_cpu_ci->num_leaves = leaves;
 
 	return 0;
+
+err_out:
+	of_node_put(np);
+	return -EINVAL;
 }
 
 #else
-- 
2.25.1


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[PATCH 3/5] ACPI: PPTT: Remove acpi_find_cache_levels()

[Pierre Gondois]

acpi_find_cache_levels() is used at a single place and is short
enough to be merged into the calling function. The removal allows
an easier renaming of the calling function in the next patch.

Also reorder the parameters in the 'reversed Christmas tree' order.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
 drivers/acpi/pptt.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index c91342dcbcd6..97c1d33822d1 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -281,19 +281,6 @@ static struct acpi_pptt_processor *acpi_find_processor_node(struct acpi_table_he
 	return NULL;
 }
 
-static int acpi_find_cache_levels(struct acpi_table_header *table_hdr,
-				  u32 acpi_cpu_id)
-{
-	int number_of_levels = 0;
-	struct acpi_pptt_processor *cpu;
-
-	cpu = acpi_find_processor_node(table_hdr, acpi_cpu_id);
-	if (cpu)
-		number_of_levels = acpi_count_levels(table_hdr, cpu);
-
-	return number_of_levels;
-}
-
 static u8 acpi_cache_type(enum cache_type type)
 {
 	switch (type) {
@@ -613,9 +600,10 @@ static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag)
  */
 int acpi_find_last_cache_level(unsigned int cpu)
 {
-	u32 acpi_cpu_id;
+	struct acpi_pptt_processor *cpu_node;
 	struct acpi_table_header *table;
 	int number_of_levels = 0;
+	u32 acpi_cpu_id;
 
 	table = acpi_get_pptt();
 	if (!table)
@@ -624,7 +612,10 @@ int acpi_find_last_cache_level(unsigned int cpu)
 	pr_debug("Cache Setup find last level CPU=%d\n", cpu);
 
 	acpi_cpu_id = get_acpi_id_for_cpu(cpu);
-	number_of_levels = acpi_find_cache_levels(table, acpi_cpu_id);
+	cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
+	if (cpu_node)
+		number_of_levels = acpi_count_levels(table, cpu_node);
+
 	pr_debug("Cache Setup find last level level=%d\n", number_of_levels);
 
 	return number_of_levels;
-- 
2.25.1


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[PATCH 4/5] ACPI: PPTT: Update acpi_find_last_cache_level() to acpi_get_cache_info()

[Pierre Gondois]

acpi_find_last_cache_level() allows to find the last level of cache
for a given CPU. The function is only called on arm64 ACPI based
platforms to check for cache information that would be missing in
the CLIDR_EL1 register.
To allow populating (struct cpu_cacheinfo).num_leaves by only parsing
a PPTT, update acpi_find_last_cache_level() to get the 'split_levels',
i.e. the number of cache levels being split in data/instruction
caches.

It is assumed that there will not be data/instruction caches above a
unified cache.
If a split level consist of one data cache and no instruction cache
(or opposite), then the missing cache will still be populated
by default with minimal cache information, and maximal cpumask
(all non-existing caches have the same fw_token).

Suggested-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
 arch/arm64/kernel/cacheinfo.c |  9 +++--
 drivers/acpi/pptt.c           | 69 ++++++++++++++++++++++++-----------
 include/linux/cacheinfo.h     |  8 ++--
 3 files changed, 58 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index 97c42be71338..164255651d64 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -46,7 +46,7 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
 int init_cache_level(unsigned int cpu)
 {
 	unsigned int ctype, level, leaves;
-	int fw_level;
+	int fw_level, ret;
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 
 	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
@@ -61,8 +61,11 @@ int init_cache_level(unsigned int cpu)
 
 	if (acpi_disabled)
 		fw_level = of_find_last_cache_level(cpu);
-	else
-		fw_level = acpi_find_last_cache_level(cpu);
+	else {
+		ret = acpi_get_cache_info(cpu, &fw_level, NULL);
+		if (ret < 0)
+			return ret;
+	}
 
 	if (fw_level < 0)
 		return fw_level;
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index 97c1d33822d1..72a6ddc1c555 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -81,6 +81,7 @@ static inline bool acpi_pptt_match_type(int table_type, int type)
  * acpi_pptt_walk_cache() - Attempt to find the requested acpi_pptt_cache
  * @table_hdr: Pointer to the head of the PPTT table
  * @local_level: passed res reflects this cache level
+ * @split_levels: Number of split cache levels (data/instruction).
  * @res: cache resource in the PPTT we want to walk
  * @found: returns a pointer to the requested level if found
  * @level: the requested cache level
@@ -100,6 +101,7 @@ static inline bool acpi_pptt_match_type(int table_type, int type)
  */
 static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
 					 unsigned int local_level,
+					 unsigned int *split_levels,
 					 struct acpi_subtable_header *res,
 					 struct acpi_pptt_cache **found,
 					 unsigned int level, int type)
@@ -113,6 +115,12 @@ static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
 	while (cache) {
 		local_level++;
 
+		if (split_levels && (acpi_pptt_match_type(cache->attributes,
+				ACPI_PPTT_CACHE_TYPE_DATA) ||
+				acpi_pptt_match_type(cache->attributes,
+				ACPI_PPTT_CACHE_TYPE_INSTR)))
+			*split_levels = local_level;
+
 		if (local_level == level &&
 		    cache->flags & ACPI_PPTT_CACHE_TYPE_VALID &&
 		    acpi_pptt_match_type(cache->attributes, type)) {
@@ -135,8 +143,8 @@ static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
 static struct acpi_pptt_cache *
 acpi_find_cache_level(struct acpi_table_header *table_hdr,
 		      struct acpi_pptt_processor *cpu_node,
-		      unsigned int *starting_level, unsigned int level,
-		      int type)
+		      unsigned int *starting_level, unsigned int *split_levels,
+		      unsigned int level, int type)
 {
 	struct acpi_subtable_header *res;
 	unsigned int number_of_levels = *starting_level;
@@ -149,7 +157,8 @@ acpi_find_cache_level(struct acpi_table_header *table_hdr,
 		resource++;
 
 		local_level = acpi_pptt_walk_cache(table_hdr, *starting_level,
-						   res, &ret, level, type);
+						   split_levels, res, &ret,
+						   level, type);
 		/*
 		 * we are looking for the max depth. Since its potentially
 		 * possible for a given node to have resources with differing
@@ -165,29 +174,33 @@ acpi_find_cache_level(struct acpi_table_header *table_hdr,
 }
 
 /**
- * acpi_count_levels() - Given a PPTT table, and a CPU node, count the caches
+ * acpi_count_levels() - Given a PPTT table, and a CPU node, count the cache
+ * levels and split cache levels (data/instruction).
  * @table_hdr: Pointer to the head of the PPTT table
  * @cpu_node: processor node we wish to count caches for
+ * @levels: Number of levels if success.
+ * @split_levels: Number of split cache levels (data/instruction) if success.
+ * Can by NULL.
  *
  * Given a processor node containing a processing unit, walk into it and count
  * how many levels exist solely for it, and then walk up each level until we hit
  * the root node (ignore the package level because it may be possible to have
- * caches that exist across packages). Count the number of cache levels that
- * exist at each level on the way up.
+ * caches that exist across packages). Count the number of cache levels and
+ * split cache levels (data/instruction) that exist at each level on the way
+ * up.
  *
- * Return: Total number of levels found.
+ * Return: 0 on success.
  */
 static int acpi_count_levels(struct acpi_table_header *table_hdr,
-			     struct acpi_pptt_processor *cpu_node)
+				struct acpi_pptt_processor *cpu_node,
+				unsigned int *levels, unsigned int *split_levels)
 {
-	int total_levels = 0;
-
 	do {
-		acpi_find_cache_level(table_hdr, cpu_node, &total_levels, 0, 0);
+		acpi_find_cache_level(table_hdr, cpu_node, levels, split_levels, 0, 0);
 		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
 	} while (cpu_node);
 
-	return total_levels;
+	return 0;
 }
 
 /**
@@ -321,7 +334,7 @@ static struct acpi_pptt_cache *acpi_find_cache_node(struct acpi_table_header *ta
 
 	while (cpu_node && !found) {
 		found = acpi_find_cache_level(table_hdr, cpu_node,
-					      &total_levels, level, acpi_type);
+					      &total_levels, NULL, level, acpi_type);
 		*node = cpu_node;
 		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
 	}
@@ -589,36 +602,48 @@ static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag)
 }
 
 /**
- * acpi_find_last_cache_level() - Determines the number of cache levels for a PE
+ * acpi_get_cache_info() - Determine the number of cache levels and
+ * split cache levels (data/instruction) and for a PE.
  * @cpu: Kernel logical CPU number
+ * @levels: Number of levels if success.
+ * @split_levels: Number of levels being split (i.e. data/instruction)
+ * if success. Can by NULL.
  *
  * Given a logical CPU number, returns the number of levels of cache represented
  * in the PPTT. Errors caused by lack of a PPTT table, or otherwise, return 0
  * indicating we didn't find any cache levels.
  *
- * Return: Cache levels visible to this core.
+ * Return: -ENOENT if no PPTT table or no PPTT processor struct found.
+ *	   0 on success.
  */
-int acpi_find_last_cache_level(unsigned int cpu)
+int acpi_get_cache_info(unsigned int cpu, unsigned int *levels,
+				unsigned int *split_levels)
 {
 	struct acpi_pptt_processor *cpu_node;
 	struct acpi_table_header *table;
-	int number_of_levels = 0;
 	u32 acpi_cpu_id;
 
+	*levels = 0;
+	if (split_levels)
+		*split_levels = 0;
+
 	table = acpi_get_pptt();
 	if (!table)
 		return -ENOENT;
 
-	pr_debug("Cache Setup find last level CPU=%d\n", cpu);
+	pr_debug("Cache Setup: find cache levels for CPU=%d\n", cpu);
 
 	acpi_cpu_id = get_acpi_id_for_cpu(cpu);
 	cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
-	if (cpu_node)
-		number_of_levels = acpi_count_levels(table, cpu_node);
+	if (!cpu_node)
+		return -ENOENT;
 
-	pr_debug("Cache Setup find last level level=%d\n", number_of_levels);
+	acpi_count_levels(table, cpu_node, levels, split_levels);
 
-	return number_of_levels;
+	pr_debug("Cache Setup: last_level=%d split_levels=%d\n",
+			*levels, split_levels ? *split_levels : -1);
+
+	return 0;
 }
 
 /**
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index ff0328f3fbb0..f992d81d211f 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -88,19 +88,21 @@ bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y);
 int detect_cache_attributes(unsigned int cpu);
 #ifndef CONFIG_ACPI_PPTT
 /*
- * acpi_find_last_cache_level is only called on ACPI enabled
+ * acpi_get_cache_info() is only called on ACPI enabled
  * platforms using the PPTT for topology. This means that if
  * the platform supports other firmware configuration methods
  * we need to stub out the call when ACPI is disabled.
  * ACPI enabled platforms not using PPTT won't be making calls
  * to this function so we need not worry about them.
  */
-static inline int acpi_find_last_cache_level(unsigned int cpu)
+static inline int acpi_get_cache_info(unsigned int cpu,
+			unsigned int *levels, unsigned int *split_levels)
 {
 	return 0;
 }
 #else
-int acpi_find_last_cache_level(unsigned int cpu);
+int acpi_get_cache_info(unsigned int cpu,
+			unsigned int *levels, unsigned int *split_levels);
 #endif
 
 const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);
-- 
2.25.1


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[PATCH 5/5] arch_topology: Build cacheinfo from primary CPU

[Pierre Gondois]

commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection
in the CPU hotplug path")
adds a call to detect_cache_attributes() to populate the cacheinfo
before updating the siblings mask. detect_cache_attributes() allocates
memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT
kernels, on secondary CPUs, this triggers a:
  'BUG: sleeping function called from invalid context' [1]
as the code is executed with preemption and interrupts disabled.

The primary CPU was previously storing the cache information using
the now removed (struct cpu_topology).llc_id:
commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from
the CPU topology")

allocate_cache_info() tries to build the cacheinfo from the primary
CPU prior secondary CPUs boot, if the DT/ACPI description
contains cache information.
If allocate_cache_info() fails, then fallback to the current state
for the cacheinfo allocation. [1] will be triggered in such case.

When unplugging a CPU, the cacheinfo memory cannot be freed. If it
was, then the memory would be allocated early by the re-plugged
CPU and would trigger [1].

[1]:
[    7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
[    7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
[    7.560796] preempt_count: 1, expected: 0
[    7.560797] RCU nest depth: 1, expected: 1
[    7.560799] 3 locks held by swapper/111/0:
[    7.560800]  #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
[    7.560811]  #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
[    7.560820]  #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
[    7.560824] irq event stamp: 0
[    7.560825] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
[    7.560827] hardirqs last disabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
[    7.560830] softirqs last  enabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
[    7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0
[    7.560834] Preemption disabled at:
[    7.560835] [<ffffc5f8e9fd3c28>] migrate_enable+0x30/0x130
[    7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-rt6-[...]
[    7.560841] Call trace:
[...]
[    7.560870]  __kmalloc+0xbc/0x1e8
[    7.560873]  detect_cache_attributes+0x2d4/0x5f0
[    7.560876]  update_siblings_masks+0x30/0x368
[    7.560880]  store_cpu_topology+0x78/0xb8
[    7.560883]  secondary_start_kernel+0xd0/0x198
[    7.560885]  __secondary_switched+0xb0/0xb4

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
 drivers/base/arch_topology.c | 10 ++++++-
 drivers/base/cacheinfo.c     | 53 ++++++++++++++++++++++++++++--------
 include/linux/cacheinfo.h    |  1 +
 3 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index d07a7cfa389a..4222a6d1e07b 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -825,7 +825,7 @@ __weak int __init parse_acpi_topology(void)
 #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
 void __init init_cpu_topology(void)
 {
-	int ret;
+	int cpu, ret;
 
 	reset_cpu_topology();
 	ret = parse_acpi_topology();
@@ -840,6 +840,14 @@ void __init init_cpu_topology(void)
 		reset_cpu_topology();
 		return;
 	}
+
+	for_each_possible_cpu(cpu) {
+		ret = allocate_cache_info(cpu);
+		if (ret) {
+			pr_err("Early cacheinfo failed, ret = %d\n", ret);
+			break;
+		}
+	}
 }
 
 void store_cpu_topology(unsigned int cpuid)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 6f6cd120c4f1..889d94d89e18 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -371,10 +371,6 @@ static void free_cache_attributes(unsigned int cpu)
 		return;
 
 	cache_shared_cpu_map_remove(cpu);
-
-	kfree(per_cpu_cacheinfo(cpu));
-	per_cpu_cacheinfo(cpu) = NULL;
-	cache_leaves(cpu) = 0;
 }
 
 int __weak init_cache_level(unsigned int cpu)
@@ -387,18 +383,53 @@ int __weak populate_cache_leaves(unsigned int cpu)
 	return -ENOENT;
 }
 
+int allocate_cache_info(unsigned int cpu)
+{
+	struct cpu_cacheinfo *this_cpu_ci;
+	unsigned int levels, split_levels;
+	int ret;
+
+	if (acpi_disabled)
+		ret = init_of_cache_level(cpu);
+	else {
+		ret = acpi_get_cache_info(cpu, &levels, &split_levels);
+		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 (ret < 0)
+		return ret;
+	else if (!cache_leaves(cpu))
+		return -ENOENT;
+
+	per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu),
+					sizeof(struct cacheinfo), GFP_ATOMIC);
+	if (per_cpu_cacheinfo(cpu) == NULL) {
+		cache_leaves(cpu) = 0;
+		return -ENOMEM;
+	}
+
+	return ret;
+}
+
 int detect_cache_attributes(unsigned int cpu)
 {
 	int ret;
 
-	/* Since early detection of the cacheinfo is allowed via this
-	 * function and this also gets called as CPU hotplug callbacks via
-	 * cacheinfo_cpu_online, the initialisation can be skipped and only
-	 * CPU maps can be updated as the CPU online status would be update
-	 * if called via cacheinfo_cpu_online path.
+	/* Since early initialization/allocation of the cacheinfo is allowed
+	 * via allocate_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.
 	 */
 	if (per_cpu_cacheinfo(cpu))
-		goto update_cpu_map;
+		goto populate_leaves;
 
 	if (init_cache_level(cpu) || !cache_leaves(cpu))
 		return -ENOENT;
@@ -410,6 +441,7 @@ int detect_cache_attributes(unsigned int cpu)
 		return -ENOMEM;
 	}
 
+populate_leaves:
 	/*
 	 * populate_cache_leaves() may completely setup the cache leaves and
 	 * shared_cpu_map or it may leave it partially setup.
@@ -418,7 +450,6 @@ int detect_cache_attributes(unsigned int cpu)
 	if (ret)
 		goto free_ci;
 
-update_cpu_map:
 	/*
 	 * For systems using DT for cache hierarchy, fw_token
 	 * and shared_cpu_map will be set up here only if they are
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index f992d81d211f..7d390806b788 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -85,6 +85,7 @@ int populate_cache_leaves(unsigned int cpu);
 int cache_setup_acpi(unsigned int cpu);
 bool last_level_cache_is_valid(unsigned int cpu);
 bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y);
+int allocate_cache_info(unsigned int cpu);
 int detect_cache_attributes(unsigned int cpu);
 #ifndef CONFIG_ACPI_PPTT
 /*
-- 
2.25.1


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Re: [PATCH 0/5] arch_topology: Build cacheinfo from primary CPU

[Pierre Gondois]

+ Rob Herring
+ Jeremy Linton

On 11/8/22 12:04, Pierre Gondois wrote:
> [1] and [2] build the CPU topology from the cacheinfo information for
> both DT/ACPI based systems and remove (struct cpu_topology).llc_id
> which was used by ACPI only.
> 
> Creating the cacheinfo for secondary CPUs is done during early boot.
> Preemption and interrupts are disabled at this stage. On PREEMPT_RT
> kernels, allocating memory (and parsing the PPTT table for ACPI based
> systems) triggers a:
>    'BUG: sleeping function called from invalid context' [4]
> 
> To prevent this bug, allocate the cacheinfo from the primary CPU when
> preemption and interrupts are enabled and before booting secondary
> CPUs. The cache levels/leaves are computed from DT/ACPI PPTT information
> only, without relying on the arm64 CLIDR_EL1 register.
> If no cache information is found in the DT/ACPI PPTT, then fallback
> to the current state, triggering [4] on PREEMPT_RT kernels.
> 
> Patches to update the arm64 device trees that have incomplete cacheinfo
> (mostly for missing the 'cache-level' or 'cache-unified' property)
> have been sent at [3].
> 
> Tested platforms:
> - ACPI + PPTT: Ampere Altra, Ampere eMAG, Cavium ThunderX2,
>    Kunpeng 920, Juno-r2
> - DT: rb5, db845c, Juno-r2
> 
> [1] https://lore.kernel.org/all/20220704101605.1318280-1-sudeep.holla@arm.com/
> [2] https://lore.kernel.org/all/20220720-arch_topo_fixes-v3-0-43d696288e84@arm.com/
> [3] https://lore.kernel.org/all/20221107155825.1644604-1-pierre.gondois@arm.com/
> [4] On an Ampere Altra, with PREEMPT_RT kernel based on v6.0.0-rc4:
> 
> 
> [    7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
> [    7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
> [    7.560796] preempt_count: 1, expected: 0
> [    7.560797] RCU nest depth: 1, expected: 1
> [    7.560799] 3 locks held by swapper/111/0:
> [    7.560800]  #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
> [    7.560811]  #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
> [    7.560820]  #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
> [    7.560824] irq event stamp: 0
> [    7.560825] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
> [    7.560827] hardirqs last disabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
> [    7.560830] softirqs last  enabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
> [    7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [    7.560834] Preemption disabled at:
> [    7.560835] [<ffffc5f8e9fd3c28>] migrate_enable+0x30/0x130
> [    7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-[...]
> [    7.560841] Call trace:
> [...]
> [    7.560870]  __kmalloc+0xbc/0x1e8
> [    7.560873]  detect_cache_attributes+0x2d4/0x5f0
> [    7.560876]  update_siblings_masks+0x30/0x368
> [    7.560880]  store_cpu_topology+0x78/0xb8
> [    7.560883]  secondary_start_kernel+0xd0/0x198
> [    7.560885]  __secondary_switched+0xb0/0xb4
> 
> Pierre Gondois (5):
>    cacheinfo: Use riscv's init_cache_level() as generic OF implem
>    cacheinfo: Return error code in init_of_cache_level()
>    ACPI: PPTT: Remove acpi_find_cache_levels()
>    ACPI: PPTT: Update acpi_find_last_cache_level() to
>      acpi_get_cache_info()
>    arch_topology: Build cacheinfo from primary CPU
> 
>   arch/arm64/kernel/cacheinfo.c |   9 ++-
>   arch/riscv/kernel/cacheinfo.c |  39 +------------
>   drivers/acpi/pptt.c           |  86 +++++++++++++++++------------
>   drivers/base/arch_topology.c  |  10 +++-
>   drivers/base/cacheinfo.c      | 101 ++++++++++++++++++++++++++++++----
>   include/linux/cacheinfo.h     |  10 +++-
>   6 files changed, 164 insertions(+), 91 deletions(-)
> 

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Re: [PATCH 0/5] arch_topology: Build cacheinfo from primary CPU

[Conor Dooley]

On Tue, Nov 08, 2022 at 12:04:16PM +0100, Pierre Gondois wrote:
> [1] and [2] build the CPU topology from the cacheinfo information for
> both DT/ACPI based systems and remove (struct cpu_topology).llc_id
> which was used by ACPI only.
> 
> Creating the cacheinfo for secondary CPUs is done during early boot.
> Preemption and interrupts are disabled at this stage. On PREEMPT_RT
> kernels, allocating memory (and parsing the PPTT table for ACPI based
> systems) triggers a:
>   'BUG: sleeping function called from invalid context' [4]
> 
> To prevent this bug, allocate the cacheinfo from the primary CPU when
> preemption and interrupts are enabled and before booting secondary
> CPUs. The cache levels/leaves are computed from DT/ACPI PPTT information
> only, without relying on the arm64 CLIDR_EL1 register.
> If no cache information is found in the DT/ACPI PPTT, then fallback
> to the current state, triggering [4] on PREEMPT_RT kernels.
> 
> Patches to update the arm64 device trees that have incomplete cacheinfo
> (mostly for missing the 'cache-level' or 'cache-unified' property)
> have been sent at [3].

FWIW checkpatch whinges a bit at your final two patches [a]. The RISC-V
code movement looks okay though, no new warnings and the like.

[a] - https://patchwork.kernel.org/project/linux-riscv/list/?series=693175

> 
> Tested platforms:
> - ACPI + PPTT: Ampere Altra, Ampere eMAG, Cavium ThunderX2,
>   Kunpeng 920, Juno-r2
> - DT: rb5, db845c, Juno-r2
> 
> [1] https://lore.kernel.org/all/20220704101605.1318280-1-sudeep.holla@arm.com/
> [2] https://lore.kernel.org/all/20220720-arch_topo_fixes-v3-0-43d696288e84@arm.com/
> [3] https://lore.kernel.org/all/20221107155825.1644604-1-pierre.gondois@arm.com/
> [4] On an Ampere Altra, with PREEMPT_RT kernel based on v6.0.0-rc4:
> 
> 
> [    7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
> [    7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
> [    7.560796] preempt_count: 1, expected: 0
> [    7.560797] RCU nest depth: 1, expected: 1
> [    7.560799] 3 locks held by swapper/111/0:
> [    7.560800]  #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
> [    7.560811]  #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
> [    7.560820]  #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
> [    7.560824] irq event stamp: 0
> [    7.560825] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
> [    7.560827] hardirqs last disabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
> [    7.560830] softirqs last  enabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8
> [    7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [    7.560834] Preemption disabled at:
> [    7.560835] [<ffffc5f8e9fd3c28>] migrate_enable+0x30/0x130
> [    7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-[...]
> [    7.560841] Call trace:
> [...]
> [    7.560870]  __kmalloc+0xbc/0x1e8
> [    7.560873]  detect_cache_attributes+0x2d4/0x5f0
> [    7.560876]  update_siblings_masks+0x30/0x368
> [    7.560880]  store_cpu_topology+0x78/0xb8
> [    7.560883]  secondary_start_kernel+0xd0/0x198
> [    7.560885]  __secondary_switched+0xb0/0xb4
> 
> Pierre Gondois (5):
>   cacheinfo: Use riscv's init_cache_level() as generic OF implem
>   cacheinfo: Return error code in init_of_cache_level()
>   ACPI: PPTT: Remove acpi_find_cache_levels()
>   ACPI: PPTT: Update acpi_find_last_cache_level() to
>     acpi_get_cache_info()
>   arch_topology: Build cacheinfo from primary CPU
> 
>  arch/arm64/kernel/cacheinfo.c |   9 ++-
>  arch/riscv/kernel/cacheinfo.c |  39 +------------
>  drivers/acpi/pptt.c           |  86 +++++++++++++++++------------
>  drivers/base/arch_topology.c  |  10 +++-
>  drivers/base/cacheinfo.c      | 101 ++++++++++++++++++++++++++++++----
>  include/linux/cacheinfo.h     |  10 +++-
>  6 files changed, 164 insertions(+), 91 deletions(-)
> 
> -- 
> 2.25.1
> 
> 
> _______________________________________________
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> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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Re: [PATCH 1/5] cacheinfo: Use riscv's init_cache_level() as generic OF implem

[Conor Dooley]

On Tue, Nov 08, 2022 at 12:04:17PM +0100, Pierre Gondois wrote:
> Riscv's implementation of init_of_cache_level() is following

heh, "Riscv" always looks a bit odd!
Code movement looks fine, nothing surface level is broken on RISC-V.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

> the Devicetree Specification v0.3 regarding caches, cf.:
> - s3.7.3 'Internal (L1) Cache Properties'
> - s3.8 'Multi-level and Shared Cache Nodes'
> 
> Allow reusing the implementation by moving it.
> 
> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
> ---
>  arch/riscv/kernel/cacheinfo.c | 39 +------------------------------
>  drivers/base/cacheinfo.c      | 44 +++++++++++++++++++++++++++++++++++
>  include/linux/cacheinfo.h     |  1 +
>  3 files changed, 46 insertions(+), 38 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
> index 90deabfe63ea..440a3df5944c 100644
> --- a/arch/riscv/kernel/cacheinfo.c
> +++ b/arch/riscv/kernel/cacheinfo.c
> @@ -115,44 +115,7 @@ static void fill_cacheinfo(struct cacheinfo **this_leaf,
>  
>  int init_cache_level(unsigned int cpu)
>  {
> -	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
> -	struct device_node *np = of_cpu_device_node_get(cpu);
> -	struct device_node *prev = NULL;
> -	int levels = 0, leaves = 0, level;
> -
> -	if (of_property_read_bool(np, "cache-size"))
> -		++leaves;
> -	if (of_property_read_bool(np, "i-cache-size"))
> -		++leaves;
> -	if (of_property_read_bool(np, "d-cache-size"))
> -		++leaves;
> -	if (leaves > 0)
> -		levels = 1;
> -
> -	prev = np;
> -	while ((np = of_find_next_cache_node(np))) {
> -		of_node_put(prev);
> -		prev = np;
> -		if (!of_device_is_compatible(np, "cache"))
> -			break;
> -		if (of_property_read_u32(np, "cache-level", &level))
> -			break;
> -		if (level <= levels)
> -			break;
> -		if (of_property_read_bool(np, "cache-size"))
> -			++leaves;
> -		if (of_property_read_bool(np, "i-cache-size"))
> -			++leaves;
> -		if (of_property_read_bool(np, "d-cache-size"))
> -			++leaves;
> -		levels = level;
> -	}
> -
> -	of_node_put(np);
> -	this_cpu_ci->num_levels = levels;
> -	this_cpu_ci->num_leaves = leaves;
> -
> -	return 0;
> +	return init_of_cache_level(cpu);
>  }
>  
>  int populate_cache_leaves(unsigned int cpu)
> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> index 4b5cd08c5a65..a4308b48dd3e 100644
> --- a/drivers/base/cacheinfo.c
> +++ b/drivers/base/cacheinfo.c
> @@ -224,8 +224,52 @@ static int cache_setup_of_node(unsigned int cpu)
>  
>  	return 0;
>  }
> +
> +int init_of_cache_level(unsigned int cpu)
> +{
> +	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
> +	struct device_node *np = of_cpu_device_node_get(cpu);
> +	struct device_node *prev = NULL;
> +	int levels = 0, leaves = 0, level;
> +
> +	if (of_property_read_bool(np, "cache-size"))
> +		++leaves;
> +	if (of_property_read_bool(np, "i-cache-size"))
> +		++leaves;
> +	if (of_property_read_bool(np, "d-cache-size"))
> +		++leaves;
> +	if (leaves > 0)
> +		levels = 1;
> +
> +	prev = np;
> +	while ((np = of_find_next_cache_node(np))) {
> +		of_node_put(prev);
> +		prev = np;
> +		if (!of_device_is_compatible(np, "cache"))
> +			break;
> +		if (of_property_read_u32(np, "cache-level", &level))
> +			break;
> +		if (level <= levels)
> +			break;
> +		if (of_property_read_bool(np, "cache-size"))
> +			++leaves;
> +		if (of_property_read_bool(np, "i-cache-size"))
> +			++leaves;
> +		if (of_property_read_bool(np, "d-cache-size"))
> +			++leaves;
> +		levels = level;
> +	}
> +
> +	of_node_put(np);
> +	this_cpu_ci->num_levels = levels;
> +	this_cpu_ci->num_leaves = leaves;
> +
> +	return 0;
> +}
> +
>  #else
>  static inline int cache_setup_of_node(unsigned int cpu) { return 0; }
> +int init_of_cache_level(unsigned int cpu) { return 0; }
>  #endif
>  
>  int __weak cache_setup_acpi(unsigned int cpu)
> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
> index 00b7a6ae8617..ff0328f3fbb0 100644
> --- a/include/linux/cacheinfo.h
> +++ b/include/linux/cacheinfo.h
> @@ -80,6 +80,7 @@ struct cpu_cacheinfo {
>  
>  struct cpu_cacheinfo *get_cpu_cacheinfo(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);
>  int cache_setup_acpi(unsigned int cpu);
>  bool last_level_cache_is_valid(unsigned int cpu);
> -- 
> 2.25.1
> 

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Re: [PATCH 1/5] cacheinfo: Use riscv's init_cache_level() as generic OF implem

[Sudeep Holla]

On Tue, Nov 08, 2022 at 02:07:41PM +0000, Conor Dooley wrote:
> On Tue, Nov 08, 2022 at 12:04:17PM +0100, Pierre Gondois wrote:
> > Riscv's implementation of init_of_cache_level() is following
> 
> heh, "Riscv" always looks a bit odd!
> Code movement looks fine, nothing surface level is broken on RISC-V.
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
>
Thanks for the review and testing. I was planning to ask Pierre to cc you
next time but you seem to have covered that for me :).

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Re: [PATCH 1/5] cacheinfo: Use riscv's init_cache_level() as generic OF implem

[Sudeep Holla]

On Tue, Nov 08, 2022 at 12:04:17PM +0100, Pierre Gondois wrote:
> Riscv's implementation of init_of_cache_level() is following
> the Devicetree Specification v0.3 regarding caches, cf.:
> - s3.7.3 'Internal (L1) Cache Properties'
> - s3.8 'Multi-level and Shared Cache Nodes'
> 
> Allow reusing the implementation by moving it.
>

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

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Re: [PATCH 2/5] cacheinfo: Return error code in init_of_cache_level()

[Sudeep Holla]

On Tue, Nov 08, 2022 at 12:04:18PM +0100, Pierre Gondois wrote:
> Make init_of_cache_level() return an error code when the cache
> information parsing fails to help detecting missing information.
> 
> init_of_cache_level() is only called for riscv. Returning an error
> code instead of 0 will prevent detect_cache_attributes() to allocate
> memory if an incomplete DT is parsed.
>

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

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Re: [PATCH 1/5] cacheinfo: Use riscv's init_cache_level() as generic OF implem

[Sudeep Holla]

On Tue, Nov 08, 2022 at 04:03:23PM +0000, Sudeep Holla wrote:
> On Tue, Nov 08, 2022 at 12:04:17PM +0100, Pierre Gondois wrote:
> > Riscv's implementation of init_of_cache_level() is following
> > the Devicetree Specification v0.3 regarding caches, cf.:
> > - s3.7.3 'Internal (L1) Cache Properties'
> > - s3.8 'Multi-level and Shared Cache Nodes'
> > 
> > Allow reusing the implementation by moving it.
> >
> 
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> 

Forgot to mention earlier, I prefer to
s/riscv/RISC-V/
s/implem/implementation/

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Re: [PATCH 3/5] ACPI: PPTT: Remove acpi_find_cache_levels()

[Sudeep Holla]

On Tue, Nov 08, 2022 at 12:04:19PM +0100, Pierre Gondois wrote:
> acpi_find_cache_levels() is used at a single place and is short
> enough to be merged into the calling function. The removal allows
> an easier renaming of the calling function in the next patch.
>
> Also reorder the parameters in the 'reversed Christmas tree' order.

Not sure if the above is worth mentioning explicitly. Even if you do,
'parameters' sounds very confusing to at-least me. I was searching for
the changes is some function parameters to understand what it was and
finally realised you meant the stack variable declaration order here.
Right ?


Other than that, it looks good.

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

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Re: [PATCH 3/5] ACPI: PPTT: Remove acpi_find_cache_levels()

[Pierre Gondois]

On 11/8/22 17:13, Sudeep Holla wrote:
> On Tue, Nov 08, 2022 at 12:04:19PM +0100, Pierre Gondois wrote:
>> acpi_find_cache_levels() is used at a single place and is short
>> enough to be merged into the calling function. The removal allows
>> an easier renaming of the calling function in the next patch.
>>
>> Also reorder the parameters in the 'reversed Christmas tree' order.
> 
> Not sure if the above is worth mentioning explicitly. Even if you do,
> 'parameters' sounds very confusing to at-least me. I was searching for
> the changes is some function parameters to understand what it was and
> finally realised you meant the stack variable declaration order here.
> Right ?

Yes right, I will use another word.

> 
> 
> Other than that, it looks good.
> 
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> 

Regards,
Pierre

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Re: [PATCH 1/5] cacheinfo: Use riscv's init_cache_level() as generic OF implem

[Conor Dooley]

On Tue, Nov 08, 2022 at 03:59:06PM +0000, Sudeep Holla wrote:
> On Tue, Nov 08, 2022 at 02:07:41PM +0000, Conor Dooley wrote:
> > On Tue, Nov 08, 2022 at 12:04:17PM +0100, Pierre Gondois wrote:
> > > Riscv's implementation of init_of_cache_level() is following
> > 
> > heh, "Riscv" always looks a bit odd!
> > Code movement looks fine, nothing surface level is broken on RISC-V.
> > Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> >
> Thanks for the review and testing. I was planning to ask Pierre to cc you
> next time but you seem to have covered that for me :).

Ye no worries.
Feel free to add some sort of "R: Conor Dooley <conor@kernel.org>" entry
where appropriate if you want to make sure I'll take a look - but I
should see it anyway if it goes to the riscv list.
Up to you.


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Re: [PATCH 4/5] ACPI: PPTT: Update acpi_find_last_cache_level() to acpi_get_cache_info()

[Jeremy Linton]

Hi,

Thanks for fixing this!


Aside from one somewhat significant comment below this is all looks fine 
to me:

Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>


On 11/8/22 05:04, Pierre Gondois wrote:
> acpi_find_last_cache_level() allows to find the last level of cache
> for a given CPU. The function is only called on arm64 ACPI based
> platforms to check for cache information that would be missing in
> the CLIDR_EL1 register.
> To allow populating (struct cpu_cacheinfo).num_leaves by only parsing
> a PPTT, update acpi_find_last_cache_level() to get the 'split_levels',
> i.e. the number of cache levels being split in data/instruction
> caches.
> 
> It is assumed that there will not be data/instruction caches above a
> unified cache.
> If a split level consist of one data cache and no instruction cache
> (or opposite), then the missing cache will still be populated
> by default with minimal cache information, and maximal cpumask
> (all non-existing caches have the same fw_token).
> 
> Suggested-by: Jeremy Linton <jeremy.linton@arm.com>
> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
> ---
>   arch/arm64/kernel/cacheinfo.c |  9 +++--
>   drivers/acpi/pptt.c           | 69 ++++++++++++++++++++++++-----------
>   include/linux/cacheinfo.h     |  8 ++--
>   3 files changed, 58 insertions(+), 28 deletions(-)
> 
> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
> index 97c42be71338..164255651d64 100644
> --- a/arch/arm64/kernel/cacheinfo.c
> +++ b/arch/arm64/kernel/cacheinfo.c
> @@ -46,7 +46,7 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
>   int init_cache_level(unsigned int cpu)
>   {
>   	unsigned int ctype, level, leaves;
> -	int fw_level;
> +	int fw_level, ret;
>   	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
>   
>   	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
> @@ -61,8 +61,11 @@ int init_cache_level(unsigned int cpu)
>   
>   	if (acpi_disabled)
>   		fw_level = of_find_last_cache_level(cpu);
> -	else
> -		fw_level = acpi_find_last_cache_level(cpu);
> +	else {
> +		ret = acpi_get_cache_info(cpu, &fw_level, NULL);
> +		if (ret < 0)
> +			return ret;
> +	}
>   
>   	if (fw_level < 0)
>   		return fw_level;
> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> index 97c1d33822d1..72a6ddc1c555 100644
> --- a/drivers/acpi/pptt.c
> +++ b/drivers/acpi/pptt.c
> @@ -81,6 +81,7 @@ static inline bool acpi_pptt_match_type(int table_type, int type)
>    * acpi_pptt_walk_cache() - Attempt to find the requested acpi_pptt_cache
>    * @table_hdr: Pointer to the head of the PPTT table
>    * @local_level: passed res reflects this cache level
> + * @split_levels: Number of split cache levels (data/instruction).
>    * @res: cache resource in the PPTT we want to walk
>    * @found: returns a pointer to the requested level if found
>    * @level: the requested cache level
> @@ -100,6 +101,7 @@ static inline bool acpi_pptt_match_type(int table_type, int type)
>    */
>   static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
>   					 unsigned int local_level,
> +					 unsigned int *split_levels,
>   					 struct acpi_subtable_header *res,
>   					 struct acpi_pptt_cache **found,
>   					 unsigned int level, int type)
> @@ -113,6 +115,12 @@ static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
>   	while (cache) {
>   		local_level++;
>   
> +		if (split_levels && (acpi_pptt_match_type(cache->attributes,
> +				ACPI_PPTT_CACHE_TYPE_DATA) ||
> +				acpi_pptt_match_type(cache->attributes,
> +				ACPI_PPTT_CACHE_TYPE_INSTR)))
> +			*split_levels = local_level;
> +

I think for maximum defense/spec compliance you need to validate the 
CACHE_TYPE_VALID flag before checking this. As its done in the next line 
too, it might be cleaner to consolidate the two checks.

>   		if (local_level == level &&
>   		    cache->flags & ACPI_PPTT_CACHE_TYPE_VALID &&
>   		    acpi_pptt_match_type(cache->attributes, type)) {
> @@ -135,8 +143,8 @@ static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
>   static struct acpi_pptt_cache *
>   acpi_find_cache_level(struct acpi_table_header *table_hdr,
>   		      struct acpi_pptt_processor *cpu_node,
> -		      unsigned int *starting_level, unsigned int level,
> -		      int type)
> +		      unsigned int *starting_level, unsigned int *split_levels,
> +		      unsigned int level, int type)
>   {
>   	struct acpi_subtable_header *res;
>   	unsigned int number_of_levels = *starting_level;
> @@ -149,7 +157,8 @@ acpi_find_cache_level(struct acpi_table_header *table_hdr,
>   		resource++;
>   
>   		local_level = acpi_pptt_walk_cache(table_hdr, *starting_level,
> -						   res, &ret, level, type);
> +						   split_levels, res, &ret,
> +						   level, type);
>   		/*
>   		 * we are looking for the max depth. Since its potentially
>   		 * possible for a given node to have resources with differing
> @@ -165,29 +174,33 @@ acpi_find_cache_level(struct acpi_table_header *table_hdr,
>   }
>   
>   /**
> - * acpi_count_levels() - Given a PPTT table, and a CPU node, count the caches
> + * acpi_count_levels() - Given a PPTT table, and a CPU node, count the cache
> + * levels and split cache levels (data/instruction).
>    * @table_hdr: Pointer to the head of the PPTT table
>    * @cpu_node: processor node we wish to count caches for
> + * @levels: Number of levels if success.
> + * @split_levels: Number of split cache levels (data/instruction) if success.
> + * Can by NULL.
nitpick: I think usually you want to indent/align multiple line argument 
comments so its clear your talking about the argument.

See: 
https://elixir.bootlin.com/linux/v6.1-rc4/source/Documentation/doc-guide/kernel-doc.rst#L107

>    *
>    * Given a processor node containing a processing unit, walk into it and count
>    * how many levels exist solely for it, and then walk up each level until we hit
>    * the root node (ignore the package level because it may be possible to have
> - * caches that exist across packages). Count the number of cache levels that
> - * exist at each level on the way up.
> + * caches that exist across packages). Count the number of cache levels and
> + * split cache levels (data/instruction) that exist at each level on the way
> + * up.
>    *
> - * Return: Total number of levels found.
> + * Return: 0 on success.
>    */
>   static int acpi_count_levels(struct acpi_table_header *table_hdr,
> -			     struct acpi_pptt_processor *cpu_node)
> +				struct acpi_pptt_processor *cpu_node,
> +				unsigned int *levels, unsigned int *split_levels)
>   {
> -	int total_levels = 0;
> - >   	do {
> -		acpi_find_cache_level(table_hdr, cpu_node, &total_levels, 0, 0);
> +		acpi_find_cache_level(table_hdr, cpu_node, levels, split_levels, 0, 0);
>   		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
>   	} while (cpu_node);
>   
> -	return total_levels;
> +	return 0;
>   }
another nitpick: You might consider just making this "void" if the 
return value is always 0, and not checked later.
>   
>   /**
> @@ -321,7 +334,7 @@ static struct acpi_pptt_cache *acpi_find_cache_node(struct acpi_table_header *ta
>   
>   	while (cpu_node && !found) {
>   		found = acpi_find_cache_level(table_hdr, cpu_node,
> -					      &total_levels, level, acpi_type);
> +					      &total_levels, NULL, level, acpi_type);
>   		*node = cpu_node;
>   		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
>   	}
> @@ -589,36 +602,48 @@ static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag)
>   }
>   
>   /**
> - * acpi_find_last_cache_level() - Determines the number of cache levels for a PE
> + * acpi_get_cache_info() - Determine the number of cache levels and
> + * split cache levels (data/instruction) and for a PE.
>    * @cpu: Kernel logical CPU number
> + * @levels: Number of levels if success.
> + * @split_levels: Number of levels being split (i.e. data/instruction)
> + * if success. Can by NULL.nitpick: same as above
>    *
>    * Given a logical CPU number, returns the number of levels of cache represented
>    * in the PPTT. Errors caused by lack of a PPTT table, or otherwise, return 0
>    * indicating we didn't find any cache levels.
>    *
> - * Return: Cache levels visible to this core.
> + * Return: -ENOENT if no PPTT table or no PPTT processor struct found.
> + *	   0 on success.
>    */
> -int acpi_find_last_cache_level(unsigned int cpu)
> +int acpi_get_cache_info(unsigned int cpu, unsigned int *levels,
> +				unsigned int *split_levels)
>   {
>   	struct acpi_pptt_processor *cpu_node;
>   	struct acpi_table_header *table;
> -	int number_of_levels = 0;
>   	u32 acpi_cpu_id;
>   
> +	*levels = 0;
> +	if (split_levels)
> +		*split_levels = 0;
> +
>   	table = acpi_get_pptt();
>   	if (!table)
>   		return -ENOENT;
>   
> -	pr_debug("Cache Setup find last level CPU=%d\n", cpu);
> +	pr_debug("Cache Setup: find cache levels for CPU=%d\n", cpu);
>   
>   	acpi_cpu_id = get_acpi_id_for_cpu(cpu);
>   	cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
> -	if (cpu_node)
> -		number_of_levels = acpi_count_levels(table, cpu_node);
> +	if (!cpu_node)
> +		return -ENOENT;
>   
> -	pr_debug("Cache Setup find last level level=%d\n", number_of_levels);
> +	acpi_count_levels(table, cpu_node, levels, split_levels);
>   
> -	return number_of_levels;
> +	pr_debug("Cache Setup: last_level=%d split_levels=%d\n",
> +			*levels, split_levels ? *split_levels : -1);
> +
> +	return 0;
>   }
>   
>   /**
> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
> index ff0328f3fbb0..f992d81d211f 100644
> --- a/include/linux/cacheinfo.h
> +++ b/include/linux/cacheinfo.h
> @@ -88,19 +88,21 @@ bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y);
>   int detect_cache_attributes(unsigned int cpu);
>   #ifndef CONFIG_ACPI_PPTT
>   /*
> - * acpi_find_last_cache_level is only called on ACPI enabled
> + * acpi_get_cache_info() is only called on ACPI enabled
>    * platforms using the PPTT for topology. This means that if
>    * the platform supports other firmware configuration methods
>    * we need to stub out the call when ACPI is disabled.
>    * ACPI enabled platforms not using PPTT won't be making calls
>    * to this function so we need not worry about them.
>    */
> -static inline int acpi_find_last_cache_level(unsigned int cpu)
> +static inline int acpi_get_cache_info(unsigned int cpu,
> +			unsigned int *levels, unsigned int *split_levels)
>   {
>   	return 0;
>   }
>   #else
> -int acpi_find_last_cache_level(unsigned int cpu);
> +int acpi_get_cache_info(unsigned int cpu,
> +			unsigned int *levels, unsigned int *split_levels);

And as a final comment your free to ignore: It might reduce some patch 
churn to just add split_levels and leave the return behavior alone.

>   #endif
>   
>   const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);


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Re: [PATCH 3/5] ACPI: PPTT: Remove acpi_find_cache_levels()

[Jeremy Linton]

On 11/8/22 05:04, Pierre Gondois wrote:
> acpi_find_cache_levels() is used at a single place and is short
> enough to be merged into the calling function. The removal allows
> an easier renaming of the calling function in the next patch.
> 
> Also reorder the parameters in the 'reversed Christmas tree' order.
> 
> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>

This bit looks fine too:

Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>


> ---
>   drivers/acpi/pptt.c | 21 ++++++---------------
>   1 file changed, 6 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> index c91342dcbcd6..97c1d33822d1 100644
> --- a/drivers/acpi/pptt.c
> +++ b/drivers/acpi/pptt.c
> @@ -281,19 +281,6 @@ static struct acpi_pptt_processor *acpi_find_processor_node(struct acpi_table_he
>   	return NULL;
>   }
>   
> -static int acpi_find_cache_levels(struct acpi_table_header *table_hdr,
> -				  u32 acpi_cpu_id)
> -{
> -	int number_of_levels = 0;
> -	struct acpi_pptt_processor *cpu;
> -
> -	cpu = acpi_find_processor_node(table_hdr, acpi_cpu_id);
> -	if (cpu)
> -		number_of_levels = acpi_count_levels(table_hdr, cpu);
> -
> -	return number_of_levels;
> -}
> -
>   static u8 acpi_cache_type(enum cache_type type)
>   {
>   	switch (type) {
> @@ -613,9 +600,10 @@ static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag)
>    */
>   int acpi_find_last_cache_level(unsigned int cpu)
>   {
> -	u32 acpi_cpu_id;
> +	struct acpi_pptt_processor *cpu_node;
>   	struct acpi_table_header *table;
>   	int number_of_levels = 0;
> +	u32 acpi_cpu_id;
>   
>   	table = acpi_get_pptt();
>   	if (!table)
> @@ -624,7 +612,10 @@ int acpi_find_last_cache_level(unsigned int cpu)
>   	pr_debug("Cache Setup find last level CPU=%d\n", cpu);
>   
>   	acpi_cpu_id = get_acpi_id_for_cpu(cpu);
> -	number_of_levels = acpi_find_cache_levels(table, acpi_cpu_id);
> +	cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
> +	if (cpu_node)
> +		number_of_levels = acpi_count_levels(table, cpu_node);
> +
>   	pr_debug("Cache Setup find last level level=%d\n", number_of_levels);
>   
>   	return number_of_levels;


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