From: Fenghua Yu <fenghua...@intel.com>

Cache management software needs a name for each instance of a cache of
a particular type.

The current cacheinfo structure does not provide any information about
the underlying hardware so there is no way to expose it.

Hardware with cache management features provides means (cpuid, enumeration
etc.) to retrieve the hardware id of a particular cache instance. Cache
instances which share hardware have the same hardware id.

Add an 'id' field to struct cacheinfo to store this information. Expose
this information under the /sys/devices/system/cpu/cpu*/cache/index*/
directory as well.

Signed-off-by: Fenghua Yu <fenghua...@intel.com>
Signed-off-by: Tony Luck <tony.l...@intel.com>
---
 drivers/base/cacheinfo.c  | 5 +++++
 include/linux/cacheinfo.h | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index e9fd32e..00a9688 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -233,6 +233,7 @@ static ssize_t file_name##_show(struct device *dev,         
\
        return sprintf(buf, "%u\n", this_leaf->object);         \
 }
 
+show_one(id, id);
 show_one(level, level);
 show_one(coherency_line_size, coherency_line_size);
 show_one(number_of_sets, number_of_sets);
@@ -314,6 +315,7 @@ static ssize_t write_policy_show(struct device *dev,
        return n;
 }
 
+static DEVICE_ATTR_RO(id);
 static DEVICE_ATTR_RO(level);
 static DEVICE_ATTR_RO(type);
 static DEVICE_ATTR_RO(coherency_line_size);
@@ -327,6 +329,7 @@ static DEVICE_ATTR_RO(shared_cpu_list);
 static DEVICE_ATTR_RO(physical_line_partition);
 
 static struct attribute *cache_default_attrs[] = {
+       &dev_attr_id.attr,
        &dev_attr_type.attr,
        &dev_attr_level.attr,
        &dev_attr_shared_cpu_map.attr,
@@ -350,6 +353,8 @@ cache_default_attrs_is_visible(struct kobject *kobj,
        const struct cpumask *mask = &this_leaf->shared_cpu_map;
        umode_t mode = attr->mode;
 
+       if ((attr == &dev_attr_id.attr) && (this_leaf->attributes & CACHE_ID))
+               return mode;
        if ((attr == &dev_attr_type.attr) && this_leaf->type)
                return mode;
        if ((attr == &dev_attr_level.attr) && this_leaf->level)
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 2189935..0bcbb67 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -18,6 +18,7 @@ enum cache_type {
 
 /**
  * struct cacheinfo - represent a cache leaf node
+ * @id: This cache's id. It is unique among caches with the same (type, level).
  * @type: type of the cache - data, inst or unified
  * @level: represents the hierarchy in the multi-level cache
  * @coherency_line_size: size of each cache line usually representing
@@ -44,6 +45,7 @@ enum cache_type {
  * keeping, the remaining members form the core properties of the cache
  */
 struct cacheinfo {
+       unsigned int id;
        enum cache_type type;
        unsigned int level;
        unsigned int coherency_line_size;
@@ -61,6 +63,7 @@ struct cacheinfo {
 #define CACHE_WRITE_ALLOCATE   BIT(3)
 #define CACHE_ALLOCATE_POLICY_MASK     \
        (CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE)
+#define CACHE_ID               BIT(4)
 
        struct device_node *of_node;
        bool disable_sysfs;
-- 
2.5.0

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