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x86/CPU/AMD: Disable XSAVES on AMD family 0x17

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commit b0563468ee 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>
This commit is contained in:
Andrew Cooper 2023-03-07 17:46:43 +00:00 committed by Greg Kroah-Hartman
parent 92d1caad9f
commit 328d069e9c
1 changed files with 9 additions and 0 deletions
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9
arch/x86/kernel/cpu/amd.c
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@ -904,6 +904,15 @@ void init_spectral_chicken(struct cpuinfo_x86 *c)
}
}
#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_zn(struct cpuinfo_x86 *c)