This is a note to let you know that I've just added the patch titled
x86/CPU/AMD: Disable XSAVES on AMD family 0x17
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-cpu-amd-disable-xsaves-on-amd-family-0x17.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b0563468eeac88ebc70559d52a0b66efc37e4e9d Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Date: Tue, 7 Mar 2023 17:46:43 +0000
Subject: x86/CPU/AMD: Disable XSAVES on AMD family 0x17
From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230307174643.1240184-1-andrew.cooper3@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/amd.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -205,6 +205,15 @@ static void init_amd_k6(struct cpuinfo_x
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)
Patches currently in stable-queue which might be from andrew.cooper3@xxxxxxxxxx are
queue-5.4/x86-cpu-amd-disable-xsaves-on-amd-family-0x17.patch
