From: Emanuel Czirai Date: Fri, 2 Sep 2016 05:35:50 +0000 (+0200) Subject: x86/AMD: Apply erratum 665 on machines without a BIOS fix X-Git-Tag: firefly_0821_release~176^2~4^2~28^2~95 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=07450b30b7d94a546560106c5d9ac3aaf6e272fb;p=firefly-linux-kernel-4.4.55.git x86/AMD: Apply erratum 665 on machines without a BIOS fix commit d1992996753132e2dafe955cccb2fb0714d3cfc4 upstream. AMD F12h machines have an erratum which can cause DIV/IDIV to behave unpredictably. The workaround is to set MSRC001_1029[31] but sometimes there is no BIOS update containing that workaround so let's do it ourselves unconditionally. It is simple enough. [ Borislav: Wrote commit message. ] Signed-off-by: Emanuel Czirai Signed-off-by: Borislav Petkov Cc: Yaowu Xu Link: http://lkml.kernel.org/r/20160902053550.18097-1-bp@alien8.de Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index a8816b325162..6cb5834062a3 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -656,6 +656,17 @@ static void init_amd_gh(struct cpuinfo_x86 *c) set_cpu_bug(c, X86_BUG_AMD_TLB_MMATCH); } +#define MSR_AMD64_DE_CFG 0xC0011029 + +static void init_amd_ln(struct cpuinfo_x86 *c) +{ + /* + * Apply erratum 665 fix unconditionally so machines without a BIOS + * fix work. + */ + msr_set_bit(MSR_AMD64_DE_CFG, 31); +} + static void init_amd_bd(struct cpuinfo_x86 *c) { u64 value; @@ -713,6 +724,7 @@ static void init_amd(struct cpuinfo_x86 *c) case 6: init_amd_k7(c); break; case 0xf: init_amd_k8(c); break; case 0x10: init_amd_gh(c); break; + case 0x12: init_amd_ln(c); break; case 0x15: init_amd_bd(c); break; }