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| author |   Rudolf Marek <r.marek@assembler.cz> | 2017-11-28 22:01:06 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-12-17 13:55:02 +0100 |
| commit | f2dbad36c55e5d3a91dccbde6e8cae345fe5632f (patch) | |
| tree | d66f74d28d8c2ebe4dac3a57bf4e11ca3fbe8ca1 /arch/x86/kernel/cpu/amd.c | |
| parent | x86/cpufeature: Add User-Mode Instruction Prevention definitions (diff) | |
| download | linux-dev-f2dbad36c55e5d3a91dccbde6e8cae345fe5632f.tar.xz linux-dev-f2dbad36c55e5d3a91dccbde6e8cae345fe5632f.zip | |
x86: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD
[ Note, this is a Git cherry-pick of the following commit:
2b67799bdf25 ("x86: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD")
... for easier x86 PTI code testing and back-porting. ]
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.marek@assembler.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/bdcebe90-62c5-1f05-083c-eba7f08b2540@assembler.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index d58184b7cd44..bcb75dc97d44 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); |