| Message ID | 1528939107-17193-2-git-send-email-babu.moger@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | i386: Enable TOPOEXT to support hyperthreading on AMD CPU | expand |
On Wed, Jun 13, 2018 at 09:18:22PM -0400, Babu Moger wrote: > Enabling TOPOEXT feature might cause compatibility issues if > older kernels does not set this feature. Lets set this feature > unconditionally. > > Signed-off-by: Babu Moger <babu.moger@amd.com> > --- > target/i386/kvm.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > index 445e0e0..6f2cca7 100644 > --- a/target/i386/kvm.c > +++ b/target/i386/kvm.c > @@ -372,6 +372,12 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, > if (host_tsx_blacklisted()) { > ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE); > } > + } else if (function == 0x80000001 && reg == R_ECX) { > + /* Enabling topoext feature might cause compatibility issues if > + * older kernel does not set this feature. Lets set this feature > + * unconditionally. > + */ Thanks. I will apply and rewrite the comment as: /* * It's safe to enable TOPOEXT even if it's not returned * by GET_SUPPORTED_CPUID. Unconditionally enabling * TOPOEXT here let us keep CPU models runnable on * older kernels even when TOPOEXT is enabled. */ > + ret |= CPUID_EXT3_TOPOEXT; > } else if (function == 0x80000001 && reg == R_EDX) { > /* On Intel, kvm returns cpuid according to the Intel spec, > * so add missing bits according to the AMD spec: > -- > 1.8.3.1 >
> -----Original Message----- > From: Eduardo Habkost [mailto:ehabkost@redhat.com] > Sent: Wednesday, June 13, 2018 9:22 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 1/6] i386: Set TOPOEXT unconditionally for > comapatibility > > On Wed, Jun 13, 2018 at 09:18:22PM -0400, Babu Moger wrote: > > Enabling TOPOEXT feature might cause compatibility issues if > > older kernels does not set this feature. Lets set this feature > > unconditionally. > > > > Signed-off-by: Babu Moger <babu.moger@amd.com> > > --- > > target/i386/kvm.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > > index 445e0e0..6f2cca7 100644 > > --- a/target/i386/kvm.c > > +++ b/target/i386/kvm.c > > @@ -372,6 +372,12 @@ uint32_t > kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, > > if (host_tsx_blacklisted()) { > > ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE); > > } > > + } else if (function == 0x80000001 && reg == R_ECX) { > > + /* Enabling topoext feature might cause compatibility issues if > > + * older kernel does not set this feature. Lets set this feature > > + * unconditionally. > > + */ > > Thanks. I will apply and rewrite the comment as: Sure. Thanks > > /* > * It's safe to enable TOPOEXT even if it's not returned > * by GET_SUPPORTED_CPUID. Unconditionally enabling > * TOPOEXT here let us keep CPU models runnable on > * older kernels even when TOPOEXT is enabled. > */ > > > + ret |= CPUID_EXT3_TOPOEXT; > > } else if (function == 0x80000001 && reg == R_EDX) { > > /* On Intel, kvm returns cpuid according to the Intel spec, > > * so add missing bits according to the AMD spec: > > -- > > 1.8.3.1 > > > > -- > Eduardo
diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 445e0e0..6f2cca7 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -372,6 +372,12 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, if (host_tsx_blacklisted()) { ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE); } + } else if (function == 0x80000001 && reg == R_ECX) { + /* Enabling topoext feature might cause compatibility issues if + * older kernel does not set this feature. Lets set this feature + * unconditionally. + */ + ret |= CPUID_EXT3_TOPOEXT; } else if (function == 0x80000001 && reg == R_EDX) { /* On Intel, kvm returns cpuid according to the Intel spec, * so add missing bits according to the AMD spec:
Enabling TOPOEXT feature might cause compatibility issues if older kernels does not set this feature. Lets set this feature unconditionally. Signed-off-by: Babu Moger <babu.moger@amd.com> --- target/i386/kvm.c | 6 ++++++ 1 file changed, 6 insertions(+)