From: Borislav Petkov <b...@suse.de> 3.4.107-rc1 review patch. If anyone has any objections, please let me know.
------------------ 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 <b...@suse.de> Link: http://lkml.kernel.org/r/20140114230711.gs29...@pd.tnic Tested-by: Aravind Gopalakrishnan <aravind.gopalakrish...@amd.com> Signed-off-by: H. Peter Anvin <h...@linux.intel.com> [bwh: Backported to 3.2: - Adjust filename - Venkatesh Srinivas pointed out we should use {rd,wr}msrl_safe() to avoid crashing on KVM. This was fixed upstream by commit 8f86a7373a1c ("x86, AMD: Convert to the new bit access MSR accessors") but that's too much trouble to backport. Here we must use {rd,wr}msrl_amd_safe().] Signed-off-by: Ben Hutchings <b...@decadent.org.uk> Cc: Moritz Muehlenhoff <j...@debian.org> Cc: Venkatesh Srinivas <venkate...@google.com> Signed-off-by: Zefan Li <lize...@huawei.com> --- arch/x86/include/asm/msr-index.h | 1 + arch/x86/kernel/cpu/amd.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index ccb8059..e92e1e4 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -130,6 +130,7 @@ #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_IBSFETCHCTL 0xc0011030 #define MSR_AMD64_IBSFETCHLINAD 0xc0011031 diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index a9c8a46..5beec8a 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -417,6 +417,16 @@ static void __cpuinit early_init_amd_mc(struct cpuinfo_x86 *c) c->x86_coreid_bits = bits; #endif + + /* F16h erratum 793, CVE-2013-6885 */ + if (c->x86 == 0x16 && c->x86_model <= 0xf) { + u64 val; + + if (!rdmsrl_amd_safe(MSR_AMD64_LS_CFG, &val) && + !(val & BIT(15))) + wrmsrl_amd_safe(MSR_AMD64_LS_CFG, val | BIT(15)); + } + } static void __cpuinit bsp_init_amd(struct cpuinfo_x86 *c) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
