Re: [Qemu-devel] [PATCH v8 7/8] i386: Enable TOPOEXT feature on AMD EPYC CPU

[Moger, Babu]

> -----Original Message-----
> From: Eduardo Habkost [mailto:address@hidden
> Sent: Friday, May 11, 2018 3:47 PM
> To: Moger, Babu <address@hidden>
> Cc: address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden
> Subject: Re: [Qemu-devel] [PATCH v8 7/8] i386: Enable TOPOEXT feature on
> AMD EPYC CPU
> 
> On Thu, May 10, 2018 at 03:41:47PM -0500, Babu Moger wrote:
> > Enable TOPOEXT feature on EPYC CPU. This is required to support
> > hyperthreading on VM guests. Also extend xlevel to 0x8000001E.
> >
> > Signed-off-by: Babu Moger <address@hidden>
> > Tested-by: Geoffrey McRae <address@hidden>
> > Reviewed-by: Eduardo Habkost <address@hidden>
> > ---
> >  target/i386/cpu.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index 5cfc7bb0e1..575f2416a1 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -2382,7 +2382,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> >          .features[FEAT_8000_0001_ECX] =
> >              CPUID_EXT3_OSVW | CPUID_EXT3_3DNOWPREFETCH |
> >              CPUID_EXT3_MISALIGNSSE | CPUID_EXT3_SSE4A |
> CPUID_EXT3_ABM |
> > -            CPUID_EXT3_CR8LEG | CPUID_EXT3_SVM | CPUID_EXT3_LAHF_LM,
> > +            CPUID_EXT3_CR8LEG | CPUID_EXT3_SVM | CPUID_EXT3_LAHF_LM
> |
> > +            CPUID_EXT3_TOPOEXT,
> >          .features[FEAT_7_0_EBX] =
> >              CPUID_7_0_EBX_FSGSBASE | CPUID_7_0_EBX_BMI1 |
> CPUID_7_0_EBX_AVX2 |
> >              CPUID_7_0_EBX_SMEP | CPUID_7_0_EBX_BMI2 |
> CPUID_7_0_EBX_RDSEED |
> > @@ -2427,7 +2428,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> >          .features[FEAT_8000_0001_ECX] =
> >              CPUID_EXT3_OSVW | CPUID_EXT3_3DNOWPREFETCH |
> >              CPUID_EXT3_MISALIGNSSE | CPUID_EXT3_SSE4A |
> CPUID_EXT3_ABM |
> > -            CPUID_EXT3_CR8LEG | CPUID_EXT3_SVM | CPUID_EXT3_LAHF_LM,
> > +            CPUID_EXT3_CR8LEG | CPUID_EXT3_SVM | CPUID_EXT3_LAHF_LM
> |
> > +            CPUID_EXT3_TOPOEXT,
> 
> I forgot about one thing: you'll need to add EPYC.topoext=off and
> EPYC-IBPB.topoext=off to PC_COMPAT_2_12.

Ok. Will add it.

> 
> >          .features[FEAT_8000_0008_EBX] =
> >              CPUID_8000_0008_EBX_IBPB,
> >          .features[FEAT_7_0_EBX] =
> > @@ -4540,6 +4542,11 @@ static void x86_cpu_expand_features(X86CPU
> *cpu, Error **errp)
> >              x86_cpu_adjust_level(cpu, &env->cpuid_min_xlevel, 0x8000000A);
> >          }
> >
> > +        /* TOPOEXT feature requires 0x8000001E */
> > +        if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) {
> > +            x86_cpu_adjust_level(cpu, &env->cpuid_min_xlevel, 0x8000001E);
> > +        }
> > +
> >          /* SEV requires CPUID[0x8000001F] */
> >          if (sev_enabled()) {
> >              x86_cpu_adjust_level(cpu, &env->cpuid_min_xlevel, 0x8000001F);
> > --
> > 2.17.0
> >
> >
> 
> --
> Eduardo