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[Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit

Eduardo Habkost posted 7 patches 8 years, 1 month ago
[Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
Posted by Eduardo Habkost 8 years, 1 month ago 
Add the feature name and a CPUID_7_0_EDX_SPEC_CTRL macro.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target/i386/cpu.h | 1 +
 target/i386/cpu.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 07f47997d6..de387c1311 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -667,6 +667,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
 
 #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural Network Instructions */
 #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply Accumulation Single Precision */
+#define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control */
 
 #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
 #define CPUID_XSAVE_XSAVEC     (1U << 1)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 9f4f949899..1be1642eb2 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -459,7 +459,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
-            NULL, NULL, NULL, NULL,
+            NULL, NULL, "spec-ctrl", NULL,
             NULL, NULL, NULL, NULL,
         },
         .cpuid_eax = 7,
-- 
2.14.3
Re: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
Posted by Gonglei (Arei) 8 years ago 
> -----Original Message-----
> From: Qemu-devel
> [mailto:qemu-devel-bounces+arei.gonglei=huawei.com@nongnu.org] On
> Behalf Of Eduardo Habkost
> Sent: Tuesday, January 09, 2018 11:45 PM
> To: qemu-devel@nongnu.org
> Cc: Paolo Bonzini
> Subject: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
> 
> Add the feature name and a CPUID_7_0_EDX_SPEC_CTRL macro.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  target/i386/cpu.h | 1 +
>  target/i386/cpu.c | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 07f47997d6..de387c1311 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -667,6 +667,7 @@ typedef uint32_t
> FeatureWordArray[FEATURE_WORDS];
> 
>  #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural
> Network Instructions */
>  #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply
> Accumulation Single Precision */
> +#define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control
> */
> 
>  #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
>  #define CPUID_XSAVE_XSAVEC     (1U << 1)
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 9f4f949899..1be1642eb2 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -459,7 +459,7 @@ static FeatureWordInfo
> feature_word_info[FEATURE_WORDS] = {
>              NULL, NULL, NULL, NULL,
>              NULL, NULL, NULL, NULL,
>              NULL, NULL, NULL, NULL,
> -            NULL, NULL, NULL, NULL,
> +            NULL, NULL, "spec-ctrl", NULL,
>              NULL, NULL, NULL, NULL,
>          },
>          .cpuid_eax = 7,
> --
> 2.14.3
> 
Don't we need to pass-through cupid_7_edx to guest when configuring '-cpu host'?
Otherwise how guests use IBPB/IBRS/STIPB capabilities?

Thanks,
-Gonglei
Re: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
Posted by Eduardo Habkost 8 years ago 
On Sat, Jan 13, 2018 at 03:04:44AM +0000, Gonglei (Arei) wrote:
> 
> > -----Original Message-----
> > From: Qemu-devel
> > [mailto:qemu-devel-bounces+arei.gonglei=huawei.com@nongnu.org] On
> > Behalf Of Eduardo Habkost
> > Sent: Tuesday, January 09, 2018 11:45 PM
> > To: qemu-devel@nongnu.org
> > Cc: Paolo Bonzini
> > Subject: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
> > 
> > Add the feature name and a CPUID_7_0_EDX_SPEC_CTRL macro.
> > 
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > ---
> >  target/i386/cpu.h | 1 +
> >  target/i386/cpu.c | 2 +-
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> > index 07f47997d6..de387c1311 100644
> > --- a/target/i386/cpu.h
> > +++ b/target/i386/cpu.h
> > @@ -667,6 +667,7 @@ typedef uint32_t
> > FeatureWordArray[FEATURE_WORDS];
> > 
> >  #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural
> > Network Instructions */
> >  #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply
> > Accumulation Single Precision */
> > +#define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control
> > */
> > 
> >  #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
> >  #define CPUID_XSAVE_XSAVEC     (1U << 1)
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index 9f4f949899..1be1642eb2 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -459,7 +459,7 @@ static FeatureWordInfo
> > feature_word_info[FEATURE_WORDS] = {
> >              NULL, NULL, NULL, NULL,
> >              NULL, NULL, NULL, NULL,
> >              NULL, NULL, NULL, NULL,
> > -            NULL, NULL, NULL, NULL,
> > +            NULL, NULL, "spec-ctrl", NULL,
> >              NULL, NULL, NULL, NULL,
> >          },
> >          .cpuid_eax = 7,
> > --
> > 2.14.3
> > 
> Don't we need to pass-through cupid_7_edx to guest when configuring '-cpu host'?
> Otherwise how guests use IBPB/IBRS/STIPB capabilities?

We already do.  See the check for cpu->max_features at
x86_cpu_expand_features().

Do you see something else missing?

-- 
Eduardo
Re: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
Posted by Gonglei (Arei) 8 years ago 
> -----Original Message-----
> From: Eduardo Habkost [mailto:ehabkost@redhat.com]
> Sent: Monday, January 15, 2018 8:23 PM
> To: Gonglei (Arei)
> Cc: qemu-devel@nongnu.org; Paolo Bonzini
> Subject: Re: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
> 
> On Sat, Jan 13, 2018 at 03:04:44AM +0000, Gonglei (Arei) wrote:
> >
> > > -----Original Message-----
> > > From: Qemu-devel
> > > [mailto:qemu-devel-bounces+arei.gonglei=huawei.com@nongnu.org] On
> > > Behalf Of Eduardo Habkost
> > > Sent: Tuesday, January 09, 2018 11:45 PM
> > > To: qemu-devel@nongnu.org
> > > Cc: Paolo Bonzini
> > > Subject: [Qemu-devel] [PATCH 3/7] i386: Add spec-ctrl CPUID bit
> > >
> > > Add the feature name and a CPUID_7_0_EDX_SPEC_CTRL macro.
> > >
> > > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > > ---
> > >  target/i386/cpu.h | 1 +
> > >  target/i386/cpu.c | 2 +-
> > >  2 files changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> > > index 07f47997d6..de387c1311 100644
> > > --- a/target/i386/cpu.h
> > > +++ b/target/i386/cpu.h
> > > @@ -667,6 +667,7 @@ typedef uint32_t
> > > FeatureWordArray[FEATURE_WORDS];
> > >
> > >  #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural
> > > Network Instructions */
> > >  #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply
> > > Accumulation Single Precision */
> > > +#define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation
> Control
> > > */
> > >
> > >  #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
> > >  #define CPUID_XSAVE_XSAVEC     (1U << 1)
> > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > > index 9f4f949899..1be1642eb2 100644
> > > --- a/target/i386/cpu.c
> > > +++ b/target/i386/cpu.c
> > > @@ -459,7 +459,7 @@ static FeatureWordInfo
> > > feature_word_info[FEATURE_WORDS] = {
> > >              NULL, NULL, NULL, NULL,
> > >              NULL, NULL, NULL, NULL,
> > >              NULL, NULL, NULL, NULL,
> > > -            NULL, NULL, NULL, NULL,
> > > +            NULL, NULL, "spec-ctrl", NULL,
> > >              NULL, NULL, NULL, NULL,
> > >          },
> > >          .cpuid_eax = 7,
> > > --
> > > 2.14.3
> > >
> > Don't we need to pass-through cupid_7_edx to guest when configuring '-cpu
> host'?
> > Otherwise how guests use IBPB/IBRS/STIPB capabilities?
> 
> We already do.  See the check for cpu->max_features at
> x86_cpu_expand_features().
> 
> Do you see something else missing?
> 
No, thank you. My bad. :(

Thanks,
-Gonglei

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