> -----Original Message-----
> From: Eduardo Habkost [mailto:ehabk...@redhat.com]
> Sent: Thursday, June 14, 2018 1:40 PM
> To: Moger, Babu <babu.mo...@amd.com>
> Cc: m...@redhat.com; marcel.apfelb...@gmail.com; pbonz...@redhat.com;
> r...@twiddle.net; mtosa...@redhat.com; qemu-devel@nongnu.org;
> k...@vger.kernel.org; k...@tripleback.net; ge...@hostfission.com
> Subject: Re: [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC
> CPU
>
> On Wed, Jun 13, 2018 at 09:18:23PM -0400, 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 <babu.mo...@amd.com>
> > ---
> > 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 86fb1a4..2eb26da 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -2554,7 +2554,8 @@ 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 |
> > @@ -2599,7 +2600,8 @@ 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_8000_0008_EBX] =
> > CPUID_8000_0008_EBX_IBPB,
> > .features[FEAT_7_0_EBX] =
>
> This part is OK, but it requires patch 3/6 to be included in the
> same patch.
Ok. Sure.
>
> > @@ -4667,6 +4669,11 @@ 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);
> > + }
>
> This part needs to be done more carefully to avoid breaking
> compatibility. "-machine pc-q35-2.12 -cpu Opteron_G5,+topoext"
> currently results in xlevel=0x8000001A, and this must not change.
Ok.
>
> I suggest just changing setting .xlevel=0x8000001E on EPYC at
> builtin_x86_defs[1], and worry about automatically increasing
> xlevel later.
Ok.
>
> (If you change EPYC.xlevel in builtin_x86_defs, don't forget to
> set EPYC.xlevel=0x8000000A on PC_COMPAT_2_12)
Sure.
>
> --
> Eduardo
