Re: [Qemu-devel] [PATCH 1/2] i386: remove the new CPUID 'PCONFIG' from Icelake-Server CPU model

[Robert Hoo]

On Wed, 2018-12-19 at 14:01 +0000, Daniel P. Berrangé wrote:
> On Wed, Dec 19, 2018 at 09:44:40PM +0800, Robert Hoo wrote:
> > Signed-off-by: Robert Hoo <address@hidden>
> > ---
> >  target/i386/cpu.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index 677a3bd..b6113d0 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -2613,8 +2613,7 @@ static X86CPUDefinition builtin_x86_defs[] =
> > {
> >              CPUID_7_0_ECX_AVX512VNNI | CPUID_7_0_ECX_AVX512BITALG
> > |
> >              CPUID_7_0_ECX_AVX512_VPOPCNTDQ | CPUID_7_0_ECX_LA57,
> >          .features[FEAT_7_0_EDX] =
> > -            CPUID_7_0_EDX_PCONFIG | CPUID_7_0_EDX_SPEC_CTRL |
> > -            CPUID_7_0_EDX_SPEC_CTRL_SSBD,
> > +            CPUID_7_0_EDX_SPEC_CTRL |
> > CPUID_7_0_EDX_SPEC_CTRL_SSBD,
> >          /* Missing: XSAVES (not supported by some Linux versions,
> >                  * including v4.1 to v4.12).
> >                  * KVM doesn't yet expose any XSAVES state save
> > component,
> 
> This was shipped in QEMU 3.1.0, so I don't think we can
> unconditionally
> remove it like this without breaking CPU model migration compat. 
> 
I think the sooner, the better. Take the time window that Icelake CPU
model has just shipped with QEMU 3.1.0 and is not publicly/widely used
yet.
> 
> Regards,
> Daniel