2018-02-28 22:18+0000, Moger, Babu: > > -----Original Message----- > > From: Radim Krčmář [mailto:rkrcmar@xxxxxxxxxx] > > Sent: Wednesday, February 28, 2018 12:24 PM > > To: Moger, Babu <Babu.Moger@xxxxxxx> > > Cc: pbonzini@xxxxxxxxxx; rth@xxxxxxxxxxx; ehabkost@xxxxxxxxxx; > > mtosatti@xxxxxxxxxx; qemu-devel@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; > > pixo@xxxxxxxxxxxx; Hook, Gary <Gary.Hook@xxxxxxx> > > 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 <pixo@xxxxxxxxxxxx> > > > > > > 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 <pixo@xxxxxxxxxxxx> > > > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > > > --- > > > 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 0x8000001E: > > > + 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 0xC0000000: > > > *eax = env->cpuid_xlevel2; > > > *ebx = 0; > > > -- > > > 1.8.3.1 > > >
