Commit-ID: 2b67799bdf25d19690710a88c2bce9127cf3ba6f Gitweb: https://git.kernel.org/tip/2b67799bdf25d19690710a88c2bce9127cf3ba6f Author: Rudolf Marek <r.ma...@assembler.cz> AuthorDate: Tue, 28 Nov 2017 22:01:06 +0100 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Wed, 29 Nov 2017 10:30:43 +0100
x86: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD The latest AMD AMD64 Architecture Programmer's Manual adds a CPUID feature XSaveErPtr (CPUID_Fn80000008_EBX[2]). If this feature is set, the FXSAVE, XSAVE, FXSAVEOPT, XSAVEC, XSAVES / FXRSTOR, XRSTOR, XRSTORS always save/restore error pointers, thus making the X86_BUG_FXSAVE_LEAK workaround obsolete on such CPUs. Signed-Off-By: Rudolf Marek <r.ma...@assembler.cz> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Borislav Petkov <b...@suse.de> Tested-by: Borislav Petkov <b...@suse.de> Cc: Andy Lutomirski <l...@amacapital.net> Link: https://lkml.kernel.org/r/bdcebe90-62c5-1f05-083c-eba7f08b2...@assembler.cz --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kernel/cpu/amd.c | 7 +++++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index c0b0e9e..800104c 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -266,6 +266,7 @@ /* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 13 */ #define X86_FEATURE_CLZERO (13*32+ 0) /* CLZERO instruction */ #define X86_FEATURE_IRPERF (13*32+ 1) /* Instructions Retired Count */ +#define X86_FEATURE_XSAVEERPTR (13*32+ 2) /* Always save/restore FP error pointers */ /* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */ #define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */ diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index d58184b..bcb75dc 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -804,8 +804,11 @@ static void init_amd(struct cpuinfo_x86 *c) case 0x17: init_amd_zn(c); break; } - /* Enable workaround for FXSAVE leak */ - if (c->x86 >= 6) + /* + * Enable workaround for FXSAVE leak on CPUs + * without a XSaveErPtr feature + */ + if ((c->x86 >= 6) && (!cpu_has(c, X86_FEATURE_XSAVEERPTR))) set_cpu_bug(c, X86_BUG_FXSAVE_LEAK); cpu_detect_cache_sizes(c);
