diff options
| author | Boris Ostrovsky <boris.ostrovsky@amd.com> | 2013-01-29 16:32:49 -0500 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-01-31 13:35:38 -0800 |
| commit | f0322bd341fd63261527bf84afd3272bcc2e8dd3 (patch) | |
| tree | 40138ddb8827ab5945c8d13b5ae731bc92018443 | |
| parent | 6bf08a8dcd1ef13e542f08fc3b1ce6cf64ae63b6 (diff) | |
x86, AMD: Enable WC+ memory type on family 10 processors
In some cases BIOS may not enable WC+ memory type on family 10
processors, instead converting what would be WC+ memory to CD type.
On guests using nested pages this could result in performance
degradation. This patch enables WC+.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
Link: http://lkml.kernel.org/r/1359495169-23278-1-git-send-email-ostr@amd64.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
| -rw-r--r-- | arch/x86/include/uapi/asm/msr-index.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 21 |
2 files changed, 17 insertions, 5 deletions
diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h index 433a59fb1a7..158cde98bbc 100644 --- a/arch/x86/include/uapi/asm/msr-index.h +++ b/arch/x86/include/uapi/asm/msr-index.h @@ -173,6 +173,7 @@ #define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140 #define MSR_AMD64_OSVW_STATUS 0xc0010141 #define MSR_AMD64_DC_CFG 0xc0011022 +#define MSR_AMD64_BU_CFG2 0xc001102a #define MSR_AMD64_IBSFETCHCTL 0xc0011030 #define MSR_AMD64_IBSFETCHLINAD 0xc0011031 #define MSR_AMD64_IBSFETCHPHYSAD 0xc0011032 diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index dd4a5b685a0..721ef3208eb 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -698,13 +698,11 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) if (c->x86 > 0x11) set_cpu_cap(c, X86_FEATURE_ARAT); - /* - * Disable GART TLB Walk Errors on Fam10h. We do this here - * because this is always needed when GART is enabled, even in a - * kernel which has no MCE support built in. - */ if (c->x86 == 0x10) { /* + * Disable GART TLB Walk Errors on Fam10h. We do this here + * because this is always needed when GART is enabled, even in a + * kernel which has no MCE support built in. * BIOS should disable GartTlbWlk Errors themself. If * it doesn't do it here as suggested by the BKDG. * @@ -718,6 +716,19 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) mask |= (1 << 10); wrmsrl_safe(MSR_AMD64_MCx_MASK(4), mask); } + + /* + * On family 10h BIOS may not have properly enabled WC+ support, + * causing it to be converted to CD memtype. This may result in + * performance degradation for certain nested-paging guests. + * Prevent this conversion by clearing bit 24 in + * MSR_AMD64_BU_CFG2. + */ + if (c->x86 == 0x10) { + rdmsrl(MSR_AMD64_BU_CFG2, value); + value &= ~(1ULL << 24); + wrmsrl(MSR_AMD64_BU_CFG2, value); + } } rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); |