Re: [PATCH 1/2] i386/cpu: Clear FEAT_XSAVE_COMP_{LO, HI} when XSAVE is not available

[Xiaoyao Li]

On 7/16/2020 11:15 PM, Eduardo Habkost wrote:
> On Thu, Jul 16, 2020 at 04:20:18PM +0800, Xiaoyao Li wrote:
> > Per Intel SDM vol 1, 13.2, if CPUID.1:ECX.XSAVE[bit 26] is 0, the
> > processor provides no further enumeration through CPUID function 0DH.
>
> Can you explain what's the bug you are trying to fix?
> env->features[FEAT_XSAVE_COMP_*] is already initialized as zero.

When "-cpu host", it's not zero I think.

> > Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> > ---
> >   target/i386/cpu.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index 1e5123251d74..f5f11603e805 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -6261,6 +6261,8 @@ static void x86_cpu_enable_xsave_components(X86CPU *cpu)
> >       uint64_t mask;
> >   
> >       if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) {
> > +        env->features[FEAT_XSAVE_COMP_LO] = 0;
> > +        env->features[FEAT_XSAVE_COMP_HI] = 0;
> >           return;
> >       }
> >   
> > --
> > 2.18.4