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-rw-r--r--arch/x86/kernel/process.c32
1 files changed, 24 insertions, 8 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index ad9540676fcc..28ad9f4d8b94 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -526,21 +526,37 @@ static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
}
/*
- * Check for AMD CPUs, which have potentially C1E support
+ * Check for AMD CPUs, where APIC timer interrupt does not wake up CPU from C1e.
+ * For more information see
+ * - Erratum #400 for NPT family 0xf and family 0x10 CPUs
+ * - Erratum #365 for family 0x11 (not affected because C1e not in use)
*/
static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c)
{
+ u64 val;
if (c->x86_vendor != X86_VENDOR_AMD)
- return 0;
-
- if (c->x86 < 0x0F)
- return 0;
+ goto no_c1e_idle;
/* Family 0x0f models < rev F do not have C1E */
- if (c->x86 == 0x0f && c->x86_model < 0x40)
- return 0;
+ if (c->x86 == 0x0F && c->x86_model >= 0x40)
+ return 1;
- return 1;
+ if (c->x86 == 0x10) {
+ /*
+ * check OSVW bit for CPUs that are not affected
+ * by erratum #400
+ */
+ rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, val);
+ if (val >= 2) {
+ rdmsrl(MSR_AMD64_OSVW_STATUS, val);
+ if (!(val & BIT(1)))
+ goto no_c1e_idle;
+ }
+ return 1;
+ }
+
+no_c1e_idle:
+ return 0;
}
static cpumask_var_t c1e_mask;