3.11.10.4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Borislav Petkov <bp@xxxxxxx> commit 3b56496865f9f7d9bcb2f93b44c63f274f08e3b6 upstream. This adds the workaround for erratum 793 as a precaution in case not every BIOS implements it. This addresses CVE-2013-6885. Erratum text: [Revision Guide for AMD Family 16h Models 00h-0Fh Processors, document 51810 Rev. 3.04 November 2013] 793 Specific Combination of Writes to Write Combined Memory Types and Locked Instructions May Cause Core Hang Description Under a highly specific and detailed set of internal timing conditions, a locked instruction may trigger a timing sequence whereby the write to a write combined memory type is not flushed, causing the locked instruction to stall indefinitely. Potential Effect on System Processor core hang. Suggested Workaround BIOS should set MSR C001_1020[15] = 1b. Fix Planned No fix planned [ hpa: updated description, fixed typo in MSR name ] Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: http://lkml.kernel.org/r/20140114230711.GS29865@xxxxxxx Tested-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@xxxxxxx> Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx> --- arch/x86/include/uapi/asm/msr-index.h | 1 + arch/x86/kernel/cpu/amd.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h index bb04650..228d95f 100644 --- a/arch/x86/include/uapi/asm/msr-index.h +++ b/arch/x86/include/uapi/asm/msr-index.h @@ -182,6 +182,7 @@ #define MSR_AMD64_PATCH_LOADER 0xc0010020 #define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140 #define MSR_AMD64_OSVW_STATUS 0xc0010141 +#define MSR_AMD64_LS_CFG 0xc0011020 #define MSR_AMD64_DC_CFG 0xc0011022 #define MSR_AMD64_BU_CFG2 0xc001102a #define MSR_AMD64_IBSFETCHCTL 0xc0011030 diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 08a0890..c2d6f50 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -508,6 +508,16 @@ static void early_init_amd(struct cpuinfo_x86 *c) set_cpu_cap(c, X86_FEATURE_EXTD_APICID); } #endif + + /* F16h erratum 793, CVE-2013-6885 */ + if (c->x86 == 0x16 && c->x86_model <= 0xf) { + u64 val; + + rdmsrl(MSR_AMD64_LS_CFG, val); + if (!(val & BIT(15))) + wrmsrl(MSR_AMD64_LS_CFG, val | BIT(15)); + } + } static const int amd_erratum_383[]; -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html