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| author | Andrew Cooper <andrew.cooper3@citrix.com> | 2023-03-07 20:46:43 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-17 10:30:36 +0300 |
| commit | 35769d1551f1fabec61b1951e29b51941ac1e73d (patch) | |
| tree | 8810e0ccd365543fe72468aaf293aa3e4ad9bc34 | |
| parent | f31cd5da636682caea424fa1c22679016cbfc16b (diff) | |
| download | linux-35769d1551f1fabec61b1951e29b51941ac1e73d.tar.xz | |
x86/CPU/AMD: Disable XSAVES on AMD family 0x17
commit b0563468eeac88ebc70559d52a0b66efc37e4e9d upstream.
AMD Erratum 1386 is summarised as:
XSAVES Instruction May Fail to Save XMM Registers to the Provided
State Save Area
This piece of accidental chronomancy causes the %xmm registers to
occasionally reset back to an older value.
Ignore the XSAVES feature on all AMD Zen1/2 hardware. The XSAVEC
instruction (which works fine) is equivalent on affected parts.
[ bp: Typos, move it into the F17h-specific function. ]
Reported-by: Tavis Ormandy <taviso@gmail.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230307174643.1240184-1-andrew.cooper3@citrix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index ee5d0f943ec8..265d9c05bb32 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -197,6 +197,15 @@ static void init_amd_k6(struct cpuinfo_x86 *c) return; } #endif + /* + * Work around Erratum 1386. The XSAVES instruction malfunctions in + * certain circumstances on Zen1/2 uarch, and not all parts have had + * updated microcode at the time of writing (March 2023). + * + * Affected parts all have no supervisor XSAVE states, meaning that + * the XSAVEC instruction (which works fine) is equivalent. + */ + clear_cpu_cap(c, X86_FEATURE_XSAVES); } static void init_amd_k7(struct cpuinfo_x86 *c) |