New versions of AMD processors have support to disable parts
of their L3 caches if too many MCEs are generated by the
L3 cache.
This patch provides a /sysfs interface under the cache
hierarchy to display which caches indices are disabled
(if any) and to monitoring applications to disable a
cache index.
This patch does not set an automatic policy to disable
the L3 cache. Policy decisions would need to be made
by a RAS handler. This patch merely makes it easier to
see what indices are currently disabled.
Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
diff -r e683983d4dd0 Documentation/ABI/testing/sysfs-devices-cache_disable
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/Documentation/ABI/testing/sysfs-devices-cache_disable Thu Aug 14 03:49:19 2008 -0500
@@ -0,0 +1,18 @@
+What: /sys/devices/system/cpu/cpu*/cache/index*/cache_disable_X
+Date: August 2008
+KernelVersion: 2.6.27
+Contact: mark.langsdorf@amd.com
+Description: These files exist in every cpu's cache index directories.
+ There are currently 2 cache_disable_# files in each
+ directory. Reading from these files on a supported
+ processor will return that cache disable index value
+ for that processor and node. Writing to one of these
+ files will cause the specificed cache index to be disabled.
+
+ Currently, only AMD Family 10h Processors support cache index
+ disable, and only for their L3 caches. See the BIOS and
+ Kernel Developer's Guide at
+ http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31116.PDF
+ for formatting information and other details on the
+ cache index disable.
+Users: joachim.deguara@amd.com
diff -r e683983d4dd0 arch/x86/kernel/cpu/intel_cacheinfo.c
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c Tue Aug 12 08:46:38 2008 -0500
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c Thu Aug 14 08:06:12 2008 -0500
@@ -16,6 +16,9 @@
#include <asm/processor.h>
#include <asm/smp.h>
+
+#include <linux/pci.h>
+#include <asm/k8.h>
#define LVL_1_INST 1
#define LVL_1_DATA 2
@@ -130,6 +133,7 @@ struct _cpuid4_info {
union _cpuid4_leaf_ebx ebx;
union _cpuid4_leaf_ecx ecx;
unsigned long size;
+ bool can_disable;
cpumask_t shared_cpu_map; /* future?: only cpus/node is needed */
};
@@ -251,6 +255,14 @@ static void __cpuinit amd_cpuid4(int lea
(ebx->split.ways_of_associativity + 1) - 1;
}
+static void __cpuinit
+amd_check_l3_disable(int index, struct _cpuid4_info *this_leaf)
+{
+ if (index < 3)
+ return;
+ this_leaf->can_disable = 1;
+}
+
static int __cpuinit cpuid4_cache_lookup(int index, struct _cpuid4_info *this_leaf)
{
union _cpuid4_leaf_eax eax;
@@ -258,10 +270,13 @@ static int __cpuinit cpuid4_cache_lookup
union _cpuid4_leaf_ecx ecx;
unsigned edx;
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
amd_cpuid4(index, &eax, &ebx, &ecx);
- else
- cpuid_count(4, index, &eax.full, &ebx.full, &ecx.full, &edx);
+ if (boot_cpu_data.x86 >= 0x10)
+ amd_check_l3_disable(index, this_leaf);
+ } else {
+ cpuid_count(4, index, &eax.full, &ebx.full, &ecx.full, &edx);
+ }
if (eax.split.type == CACHE_TYPE_NULL)
return -EIO; /* better error ? */
@@ -269,9 +284,9 @@ static int __cpuinit cpuid4_cache_lookup
this_leaf->ebx = ebx;
this_leaf->ecx = ecx;
this_leaf->size = (ecx.split.number_of_sets + 1) *
- (ebx.split.coherency_line_size + 1) *
- (ebx.split.physical_line_partition + 1) *
- (ebx.split.ways_of_associativity + 1);
+ (ebx.split.coherency_line_size + 1) *
+ (ebx.split.physical_line_partition + 1) *
+ (ebx.split.ways_of_associativity + 1);
return 0;
}
@@ -574,6 +589,9 @@ static DEFINE_PER_CPU(struct _index_kobj
static DEFINE_PER_CPU(struct _index_kobject *, index_kobject);
#define INDEX_KOBJECT_PTR(x, y) (&((per_cpu(index_kobject, x))[y]))
+#define to_object(k) container_of(k, struct _index_kobject, kobj)
+#define to_attr(a) container_of(a, struct _cache_attr, attr)
+
#define show_one_plus(file_name, object, val) \
static ssize_t show_##file_name \
(struct _cpuid4_info *this_leaf, char *buf) \
@@ -619,6 +637,66 @@ static inline ssize_t show_shared_cpu_li
{
return show_shared_cpu_map_func(leaf, 1, buf);
}
+
+static ssize_t show_cache_disable(struct _cpuid4_info *this_leaf, char *buf,
+ unsigned int index)
+{
+ int node = cpu_to_node(first_cpu(this_leaf->shared_cpu_map));
+ struct pci_dev *dev = get_k8_northbridge(node);
+ unsigned int reg = 0;
+
+ if (!this_leaf->can_disable)
+ return -EINVAL;
+
+ pci_read_config_dword(dev, 0x1BC + index * 4, ®);
+ return sprintf(buf, "%x\n", reg);
+}
+
+#define SHOW_CACHE_DISABLE(index) \
+static ssize_t \
+show_cache_disable_##index(struct _cpuid4_info *this_leaf, char *buf) \
+{ \
+ return show_cache_disable(this_leaf, buf, index); \
+}
+
+static ssize_t
+store_cache_disable(struct _cpuid4_info *this_leaf, const char *buf,
+ size_t count, unsigned int index)
+{
+ int node = cpu_to_node(first_cpu(this_leaf->shared_cpu_map));
+ struct pci_dev *dev = get_k8_northbridge(node);
+ ssize_t ret = 0;
+ unsigned int val;
+
+ if (!this_leaf->can_disable)
+ return -EINVAL;
+
+ ret = sscanf(buf, "%x", &val);
+ if (ret != 1)
+ return -EINVAL;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ val |= 0xc0000000;
+ pci_write_config_dword(dev, 0x1BC + index * 4, val & ~0x40000000);
+ wbinvd();
+ pci_write_config_dword(dev, 0x1BC + index * 4, val);
+ return count;
+}
+
+#define STORE_CACHE_DISABLE(index) \
+static ssize_t \
+store_cache_disable_##index(struct _cpuid4_info *this_leaf, \
+ const char *buf, size_t count) \
+{ \
+ return store_cache_disable(this_leaf, buf, count, index); \
+}
+
+SHOW_CACHE_DISABLE(0)
+STORE_CACHE_DISABLE(0)
+SHOW_CACHE_DISABLE(1)
+STORE_CACHE_DISABLE(1)
static ssize_t show_type(struct _cpuid4_info *this_leaf, char *buf) {
switch(this_leaf->eax.split.type) {
@@ -657,6 +735,12 @@ define_one_ro(shared_cpu_map);
define_one_ro(shared_cpu_map);
define_one_ro(shared_cpu_list);
+static struct _cache_attr cache_disable_0 = __ATTR(cache_disable_0, 0644,
+ show_cache_disable_0, store_cache_disable_0);
+static struct _cache_attr cache_disable_1 = __ATTR(cache_disable_1, 0644,
+ show_cache_disable_1, store_cache_disable_1);
+
+
static struct attribute * default_attrs[] = {
&type.attr,
&level.attr,
@@ -667,11 +751,10 @@ static struct attribute * default_attrs[
&size.attr,
&shared_cpu_map.attr,
&shared_cpu_list.attr,
+ &cache_disable_0.attr,
+ &cache_disable_1.attr,
NULL
};
-
-#define to_object(k) container_of(k, struct _index_kobject, kobj)
-#define to_attr(a) container_of(a, struct _cache_attr, attr)
static ssize_t show(struct kobject * kobj, struct attribute * attr, char * buf)
{
@@ -689,7 +772,15 @@ static ssize_t store(struct kobject * ko
static ssize_t store(struct kobject * kobj, struct attribute * attr,
const char * buf, size_t count)
{
- return 0;
+ struct _cache_attr *fattr = to_attr(attr);
+ struct _index_kobject *this_leaf = to_object(kobj);
+ ssize_t ret;
+
+ ret = fattr->store ?
+ fattr->store(CPUID4_INFO_IDX(this_leaf->cpu, this_leaf->index),
+ buf, count) :
+ 0;
+ return ret;
}
static struct sysfs_ops sysfs_ops = {
--
