[v14] i386: Enable TOPOEXT to support hyperthreading on AMD CPU

[Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU

Posted by Babu Moger 7 years, 8 months ago

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.moger@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] =
@@ -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);
+        }
+
         /* SEV requires CPUID[0x8000001F] */
         if (sev_enabled()) {
             x86_cpu_adjust_level(cpu, &env->cpuid_min_xlevel, 0x8000001F);
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU

Posted by Eduardo Habkost 7 years, 8 months ago

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.moger@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.

> @@ -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.

I suggest just changing setting .xlevel=0x8000001E 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=0x8000000A on PC_COMPAT_2_12)

-- 
Eduardo

Re: [Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU

Posted by Moger, Babu 7 years, 8 months ago


> -----Original Message-----
> From: Eduardo Habkost [mailto:ehabkost@redhat.com]
> Sent: Thursday, June 14, 2018 1:40 PM
> To: Moger, Babu <Babu.Moger@amd.com>
> Cc: mst@redhat.com; marcel.apfelbaum@gmail.com; pbonzini@redhat.com;
> rth@twiddle.net; mtosatti@redhat.com; qemu-devel@nongnu.org;
> kvm@vger.kernel.org; kash@tripleback.net; geoff@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.moger@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

Re: [Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU

Posted by Moger, Babu 7 years, 8 months ago


> -----Original Message-----
> From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org]
> On Behalf Of Moger, Babu
> Sent: Thursday, June 14, 2018 3:41 PM
> To: Eduardo Habkost <ehabkost@redhat.com>
> Cc: mst@redhat.com; marcel.apfelbaum@gmail.com; pbonzini@redhat.com;
> rth@twiddle.net; mtosatti@redhat.com; qemu-devel@nongnu.org;
> kvm@vger.kernel.org; kash@tripleback.net; geoff@hostfission.com
> Subject: RE: [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC
> CPU
> 
> 
> 
> > -----Original Message-----
> > From: Eduardo Habkost [mailto:ehabkost@redhat.com]
> > Sent: Thursday, June 14, 2018 1:40 PM
> > To: Moger, Babu <Babu.Moger@amd.com>
> > Cc: mst@redhat.com; marcel.apfelbaum@gmail.com;
> pbonzini@redhat.com;
> > rth@twiddle.net; mtosatti@redhat.com; qemu-devel@nongnu.org;
> > kvm@vger.kernel.org; kash@tripleback.net; geoff@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.moger@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.

Not sure if this could be a problem.  "+topoext" sets the feature bits. But xlevel is still 0x8000001A which does not look right.
I need to verify this case.
 
> 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

[Qemu-devel] [PATCH v14 1/6] i386: Set TOPOEXT unconditionally for comapatibility
[Qemu-devel] [PATCH v14 2/6] i386: Enable TOPOEXT feature on AMD EPYC CPU
[Qemu-devel] [PATCH v14 3/6] i386: Disable TOPOEXT feature on pc-2.12
[Qemu-devel] [PATCH v14 4/6] cpus: Add new function topology_supports_topoext
[Qemu-devel] [PATCH v14 5/6] i386: Disable TOPOEXT feature if it cannot be supported
[Qemu-devel] [PATCH v14 6/6] i386: Remove generic SMT thread check