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Date: Thu, 14 Aug 2008 11:48:37 -0500
From: Mark Langsdorf <mark.langsdorf@....com>
To: Greg KH <greg@...ah.com>
CC: Pavel Machek <pavel@...e.cz>, <joachim.deguara@....com>,
<gregkh@....cz>, <tglx@...utronix.de>, <mingo@...hat.com>,
<hpa@...or.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/01][retry 5] x86: L3 cache index disable for 2.6.26
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@....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@....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@....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 06:23:13 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;
+ unsigned long 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 = {
--
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