Re: [Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU
> -Original Message-
> From: kvm-ow...@vger.kernel.org [mailto:kvm-ow...@vger.kernel.org]
> On Behalf Of Moger, Babu
> Sent: Thursday, June 14, 2018 3:41 PM
> To: Eduardo Habkost
> 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
>
>
>
> > -Original Message-
> > From: Eduardo Habkost [mailto:ehabk...@redhat.com]
> > Sent: Thursday, June 14, 2018 1:40 PM
> > To: Moger, Babu
> > 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 0x801E.
> > >
> > > Signed-off-by: Babu Moger
> > > ---
> > > 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, >cpuid_min_xlevel,
> 0x800A);
> > > }
> > >
> > > +/* TOPOEXT feature requires 0x801E */
> > > +if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT)
> {
> > > +x86_cpu_adjust_level(cpu, >cpuid_min_xlevel,
> 0x801E);
> > > +}
> >
> > 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=0x801A, and this must not change.
Not sure if this could be a problem. "+topoext" sets the feature bits. But
xlevel is still 0x801A which does not look right.
I need to verify this case.
> Ok.
> >
> > I suggest just changing setting .xlevel=0x801E 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=0x800A on PC_COMPAT_2_12)
> Sure.
> >
> > --
> > Eduardo
Re: [Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU
> -Original Message-
> From: Eduardo Habkost [mailto:ehabk...@redhat.com]
> Sent: Thursday, June 14, 2018 1:40 PM
> To: Moger, Babu
> 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 0x801E.
> >
> > Signed-off-by: Babu Moger
> > ---
> > 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, >cpuid_min_xlevel, 0x800A);
> > }
> >
> > +/* TOPOEXT feature requires 0x801E */
> > +if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) {
> > +x86_cpu_adjust_level(cpu, >cpuid_min_xlevel, 0x801E);
> > +}
>
> 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=0x801A, and this must not change.
Ok.
>
> I suggest just changing setting .xlevel=0x801E 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=0x800A on PC_COMPAT_2_12)
Sure.
>
> --
> Eduardo
Re: [Qemu-devel] [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 0x801E.
>
> Signed-off-by: Babu Moger
> ---
> 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.
> @@ -4667,6 +4669,11 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error
> **errp)
> x86_cpu_adjust_level(cpu, >cpuid_min_xlevel, 0x800A);
> }
>
> +/* TOPOEXT feature requires 0x801E */
> +if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) {
> +x86_cpu_adjust_level(cpu, >cpuid_min_xlevel, 0x801E);
> +}
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=0x801A, and this must not change.
I suggest just changing setting .xlevel=0x801E on EPYC at
builtin_x86_defs[1], and worry about automatically increasing
xlevel later.
(If you change EPYC.xlevel in builtin_x86_defs, don't forget to
set EPYC.xlevel=0x800A on PC_COMPAT_2_12)
--
Eduardo
