diff options
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/setup_64.c | 4 | ||||
| -rw-r--r-- | include/asm-x86/cpufeature.h | 1 |
3 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 1ff88c7..aaa8101 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -301,6 +301,9 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) /* K6s reports MCEs but don't actually have all the MSRs */ if (c->x86 < 6) clear_bit(X86_FEATURE_MCE, c->x86_capability); + + if (cpu_has_xmm) + set_bit(X86_FEATURE_MFENCE_RDTSC, c->x86_capability); } static unsigned int __cpuinit amd_size_cache(struct cpuinfo_x86 * c, unsigned int size) diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c index 0240910..2139aa6 100644 --- a/arch/x86/kernel/setup_64.c +++ b/arch/x86/kernel/setup_64.c @@ -746,8 +746,8 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) if (c->x86 == 0xf || c->x86 == 0x10 || c->x86 == 0x11) set_cpu_cap(c, X86_FEATURE_K8); - /* RDTSC can be speculated around */ - clear_cpu_cap(c, X86_FEATURE_SYNC_RDTSC); + /* MFENCE stops RDTSC speculation */ + set_cpu_cap(c, X86_FEATURE_MFENCE_RDTSC); /* Family 10 doesn't support C states in MWAIT so don't use it */ if (c->x86 == 0x10 && !force_mwait) diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h index 75e2f78..7d53eea 100644 --- a/include/asm-x86/cpufeature.h +++ b/include/asm-x86/cpufeature.h @@ -79,6 +79,7 @@ /* 14 free */ #define X86_FEATURE_SYNC_RDTSC (3*32+15) /* RDTSC synchronizes the CPU */ #define X86_FEATURE_REP_GOOD (3*32+16) /* rep microcode works well on this CPU */ +#define X86_FEATURE_MFENCE_RDTSC (3*32+17) /* Mfence synchronizes RDTSC */ /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */ #define X86_FEATURE_XMM3 (4*32+ 0) /* Streaming SIMD Extensions-3 */ |
