Re: [Qemu-devel] [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E for AMD

2018-03-02 Thread Moger, Babu 


> -Original Message-
> From: Radim Krčmář [mailto:rkrc...@redhat.com]
> Sent: Thursday, March 1, 2018 1:57 PM
> To: Moger, Babu 
> Cc: pbonz...@redhat.com; r...@twiddle.net; ehabk...@redhat.com;
> mtosa...@redhat.com; qemu-devel@nongnu.org; k...@vger.kernel.org;
> p...@polepetko.eu; Hook, Gary 
> Subject: Re: [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E
> for AMD
> 
> 2018-02-28 22:18+, Moger, Babu:
> > > -Original Message-
> > > From: Radim Krčmář [mailto:rkrc...@redhat.com]
> > > Sent: Wednesday, February 28, 2018 12:24 PM
> > > To: Moger, Babu 
> > > Cc: pbonz...@redhat.com; r...@twiddle.net; ehabk...@redhat.com;
> > > mtosa...@redhat.com; qemu-devel@nongnu.org; k...@vger.kernel.org;
> > > p...@polepetko.eu; Hook, Gary 
> > > Subject: Re: [PATCH v2 3/5] target/i386: Add support for
> CPUID_8000_001E
> > > for AMD
> > >
> > > 2018-02-23 21:30-0500, Babu Moger:
> > > > From: Stanislav Lanci 
> > > >
> > > > Populate threads/core_id/apic_ids/socket_id when
> CPUID_EXT3_TOPOEXT
> > > > feature is supported. This is required to support hyperthreading
> > > > feature on AMD CPUS. These are supported via CPUID_8000_001E
> > > extended
> > > > functions.
> > > >
> > > > Signed-off-by: Stanislav Lanci 
> > > > Signed-off-by: Babu Moger 
> > > > ---
> > > >  target/i386/cpu.c | 8 
> > > >  1 file changed, 8 insertions(+)
> > > >
> > > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > > > index a5a480e..191e850 100644
> > > > --- a/target/i386/cpu.c
> > > > +++ b/target/i386/cpu.c
> > > > @@ -3666,6 +3666,14 @@ void cpu_x86_cpuid(CPUX86State *env,
> > > uint32_t index, uint32_t count,
> > > >  *edx = 0;
> > > >  }
> > > >  break;
> > > > +case 0x801E:
> > > > +if (env->features[FEAT_8000_0001_ECX] &
> CPUID_EXT3_TOPOEXT) {
> > > > +*eax = cpu->apic_id;
> > > > +*ebx = (cs->nr_threads - 1) << 8 | cpu->core_id;
> > >
> > > Do we somewhere assert that AMD cannot have cpu->core_id > 255?
> > > (qemu does allow weird configurations.)
> >
> > I don't see specific assert on core_id.   But, I see that qemu does not 
> > allow
> nr_cores more than 255.
> > Also I see that core_id is iterated based on nr_cores.  If you strongly
> believe we need to add assert here, I will add it.
> > Let me know.
> 
> A user can emulate AMD with x2apic and intel-iommu to allow more than
> 255 vcpus and all of them can be a separate core (or its own socket),
> which would overflow this (or the next counter).
> 
> Forbidding that crazy configuration may be preferable, but an assert
> won't hurt now,

Ok. Sure. Will add assert.

> 
> thanks.
> 
> > > Thanks.
> > >
> > > > +*ecx = cpu->socket_id;
> > > > +*edx = 0;
> > > > +}
> > > > +break;
> > > >  case 0xC000:
> > > >  *eax = env->cpuid_xlevel2;
> > > >  *ebx = 0;
> > > > --
> > > > 1.8.3.1
> > > >
>

Re: [Qemu-devel] [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E for AMD

2018-03-01 Thread Radim Krčmář 
2018-02-28 22:18+, Moger, Babu:
> > -Original Message-
> > From: Radim Krčmář [mailto:rkrc...@redhat.com]
> > Sent: Wednesday, February 28, 2018 12:24 PM
> > To: Moger, Babu 
> > Cc: pbonz...@redhat.com; r...@twiddle.net; ehabk...@redhat.com;
> > mtosa...@redhat.com; qemu-devel@nongnu.org; k...@vger.kernel.org;
> > p...@polepetko.eu; Hook, Gary 
> > Subject: Re: [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E
> > for AMD
> > 
> > 2018-02-23 21:30-0500, Babu Moger:
> > > From: Stanislav Lanci 
> > >
> > > Populate threads/core_id/apic_ids/socket_id when CPUID_EXT3_TOPOEXT
> > > feature is supported. This is required to support hyperthreading
> > > feature on AMD CPUS. These are supported via CPUID_8000_001E
> > extended
> > > functions.
> > >
> > > Signed-off-by: Stanislav Lanci 
> > > Signed-off-by: Babu Moger 
> > > ---
> > >  target/i386/cpu.c | 8 
> > >  1 file changed, 8 insertions(+)
> > >
> > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > > index a5a480e..191e850 100644
> > > --- a/target/i386/cpu.c
> > > +++ b/target/i386/cpu.c
> > > @@ -3666,6 +3666,14 @@ void cpu_x86_cpuid(CPUX86State *env,
> > uint32_t index, uint32_t count,
> > >  *edx = 0;
> > >  }
> > >  break;
> > > +case 0x801E:
> > > +if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) {
> > > +*eax = cpu->apic_id;
> > > +*ebx = (cs->nr_threads - 1) << 8 | cpu->core_id;
> > 
> > Do we somewhere assert that AMD cannot have cpu->core_id > 255?
> > (qemu does allow weird configurations.)
> 
> I don't see specific assert on core_id.   But, I see that qemu does not allow 
> nr_cores more than 255.
> Also I see that core_id is iterated based on nr_cores.  If you strongly 
> believe we need to add assert here, I will add it. 
> Let me know.

A user can emulate AMD with x2apic and intel-iommu to allow more than
255 vcpus and all of them can be a separate core (or its own socket),
which would overflow this (or the next counter).

Forbidding that crazy configuration may be preferable, but an assert
won't hurt now,

thanks.

> > Thanks.
> > 
> > > +*ecx = cpu->socket_id;
> > > +*edx = 0;
> > > +}
> > > +break;
> > >  case 0xC000:
> > >  *eax = env->cpuid_xlevel2;
> > >  *ebx = 0;
> > > --
> > > 1.8.3.1
> > >

Re: [Qemu-devel] [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E for AMD

2018-02-28 Thread Moger, Babu 

> -Original Message-
> From: Radim Krčmář [mailto:rkrc...@redhat.com]
> Sent: Wednesday, February 28, 2018 12:24 PM
> To: Moger, Babu 
> Cc: pbonz...@redhat.com; r...@twiddle.net; ehabk...@redhat.com;
> mtosa...@redhat.com; qemu-devel@nongnu.org; k...@vger.kernel.org;
> p...@polepetko.eu; Hook, Gary 
> Subject: Re: [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E
> for AMD
> 
> 2018-02-23 21:30-0500, Babu Moger:
> > From: Stanislav Lanci 
> >
> > Populate threads/core_id/apic_ids/socket_id when CPUID_EXT3_TOPOEXT
> > feature is supported. This is required to support hyperthreading
> > feature on AMD CPUS. These are supported via CPUID_8000_001E
> extended
> > functions.
> >
> > Signed-off-by: Stanislav Lanci 
> > Signed-off-by: Babu Moger 
> > ---
> >  target/i386/cpu.c | 8 
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index a5a480e..191e850 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -3666,6 +3666,14 @@ void cpu_x86_cpuid(CPUX86State *env,
> uint32_t index, uint32_t count,
> >  *edx = 0;
> >  }
> >  break;
> > +case 0x801E:
> > +if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) {
> > +*eax = cpu->apic_id;
> > +*ebx = (cs->nr_threads - 1) << 8 | cpu->core_id;
> 
> Do we somewhere assert that AMD cannot have cpu->core_id > 255?
> (qemu does allow weird configurations.)

I don't see specific assert on core_id.   But, I see that qemu does not allow 
nr_cores more than 255.
Also I see that core_id is iterated based on nr_cores.  If you strongly believe 
we need to add assert here, I will add it. 
Let me know.
 
> Thanks.
> 
> > +*ecx = cpu->socket_id;
> > +*edx = 0;
> > +}
> > +break;
> >  case 0xC000:
> >  *eax = env->cpuid_xlevel2;
> >  *ebx = 0;
> > --
> > 1.8.3.1
> >

Re: [Qemu-devel] [PATCH v2 3/5] target/i386: Add support for CPUID_8000_001E for AMD

2018-02-28 Thread Radim Krčmář 
2018-02-23 21:30-0500, Babu Moger:
> From: Stanislav Lanci 
> 
> Populate threads/core_id/apic_ids/socket_id when CPUID_EXT3_TOPOEXT
> feature is supported. This is required to support hyperthreading
> feature on AMD CPUS. These are supported via CPUID_8000_001E extended
> functions.
> 
> Signed-off-by: Stanislav Lanci 
> Signed-off-by: Babu Moger 
> ---
>  target/i386/cpu.c | 8 
>  1 file changed, 8 insertions(+)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index a5a480e..191e850 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -3666,6 +3666,14 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
> uint32_t count,
>  *edx = 0;
>  }
>  break;
> +case 0x801E:
> +if (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) {
> +*eax = cpu->apic_id;
> +*ebx = (cs->nr_threads - 1) << 8 | cpu->core_id;

Do we somewhere assert that AMD cannot have cpu->core_id > 255?
(qemu does allow weird configurations.)

Thanks.

> +*ecx = cpu->socket_id;
> +*edx = 0;
> +}
> +break;
>  case 0xC000:
>  *eax = env->cpuid_xlevel2;
>  *ebx = 0;
> -- 
> 1.8.3.1
>