Merge branch 'ioat' into dmaengine

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;