x86/cpufeature: Create a new synthetic cpu capability for machine check recovery

The Intel Software Developer Manual describes bit 24 in the MCG_CAP
MSR:

   MCG_SER_P (software error recovery support present) flag,
   bit 24 — Indicates (when set) that the processor supports
   software error recovery

But only some models with this capability bit set will actually
generate recoverable machine checks.

Check the model name and set a synthetic capability bit. Provide
a command line option to set this bit anyway in case the kernel
doesn't recognise the model name.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2e5bfb23c89800a036fb8a45fa97a74bb16bc362.1455732970.git.tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index 68ed3114c363bf7332b2515b156bf0953ca88d24..0965a71f994243e70b3ae04fe78f73263666c1af 100644 (file)
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -60,6 +60,8 @@ Machine check
                threshold to 1. Enabling this may make memory predictive failure
                analysis less effective if the bios sets thresholds for memory
                errors since we will not see details for all errors.
+   mce=recovery
+               Force-enable recoverable machine check code paths
 
    nomce (for compatibility with i386): same as mce=off
 

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 0ceb6adc8a48c41aa74072075d369bac3566c225..6663fae71b123d6b46566e8bcbdb087248b973cc 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -106,6 +106,7 @@
 #define X86_FEATURE_APERFMPERF ( 3*32+28) /* APERFMPERF */
 #define X86_FEATURE_EAGER_FPU  ( 3*32+29) /* "eagerfpu" Non lazy FPU restore */
 #define X86_FEATURE_NONSTOP_TSC_S3 ( 3*32+30) /* TSC doesn't stop in S3 state */
+#define X86_FEATURE_MCE_RECOVERY ( 3*32+31) /* cpu has recoverable machine checks */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3       ( 4*32+ 0) /* "pni" SSE-3 */

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index 2ea4527e462f133398f178a885a4b920892cd3f5..18d2ba9c8e44e398e2edd31c381150c515b63e37 100644 (file)
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -113,6 +113,7 @@ struct mca_config {
        bool ignore_ce;
        bool disabled;
        bool ser;
+       bool recovery;
        bool bios_cmci_threshold;
        u8 banks;
        s8 bootlog;

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index a006f4cd792b10d54a92eff4a3b9c6860aa5382e..b5b187c8cc072a68ebf28e80c4e2bdc5caaaedd3 100644 (file)
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1576,6 +1576,17 @@ static int __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c)
 
                if (c->x86 == 6 && c->x86_model == 45)
                        quirk_no_way_out = quirk_sandybridge_ifu;
+               /*
+                * MCG_CAP.MCG_SER_P is necessary but not sufficient to know
+                * whether this processor will actually generate recoverable
+                * machine checks. Check to see if this is an E7 model Xeon.
+                * We can't do a model number check because E5 and E7 use the
+                * same model number. E5 doesn't support recovery, E7 does.
+                */
+               if (mca_cfg.recovery || (mca_cfg.ser &&
+                       !strncmp(c->x86_model_id,
+                                "Intel(R) Xeon(R) CPU E7-", 24)))
+                       set_cpu_cap(c, X86_FEATURE_MCE_RECOVERY);
        }
        if (cfg->monarch_timeout < 0)
                cfg->monarch_timeout = 0;
@@ -2028,6 +2039,8 @@ static int __init mcheck_enable(char *str)
                cfg->bootlog = (str[0] == 'b');
        else if (!strcmp(str, "bios_cmci_threshold"))
                cfg->bios_cmci_threshold = true;
+       else if (!strcmp(str, "recovery"))
+               cfg->recovery = true;
        else if (isdigit(str[0])) {
                if (get_option(&str, &cfg->tolerant) == 2)
                        get_option(&str, &(cfg->monarch_timeout));