On Fri, Oct 20, 2023 at 11:41:13AM +0200, Maciej S. Szmigiero wrote: > On 15.03.2023 13:11, Greg Kroah-Hartman wrote: > > 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); > > } > > This is essentially a well-intended NOP since K6 well predates XSAVES, > and init_amd_k6() is *not* called for Zen CPUs. > > This workaround should have been added to init_amd_zn() function > instead. > > 4.19 and 4.14 backports of this patch have the same problem. Ick, good catch! Can you send a set of patches to fix this up? thanks, greg k-h
