| Message ID | 1518083060-5881-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Feb 08, 2018 at 05:44:20PM +0800, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > Add PV_DEDICATED hint cpuid feature bit. > [...] > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index d70954b..cf48931 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) > x86_cpu_get_supported_feature_word(w, false); > uint32_t requested_features = env->features[w]; > env->features[w] &= host_feat; > + if (cpu->pv_dedicated && (w == FEAT_KVM)) { > + env->features[w] |= CPUID_PV_DEDICATED; > + } Why do this trick here instead of just adding "pv-dedicated" to feature_word_info[FEAT_KVM].feat_names? > [...]
2018-02-09 2:12 GMT+08:00 Eduardo Habkost <ehabkost@redhat.com>: > On Thu, Feb 08, 2018 at 05:44:20PM +0800, Wanpeng Li wrote: >> From: Wanpeng Li <wanpengli@tencent.com> >> >> Add PV_DEDICATED hint cpuid feature bit. >> > [...] >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c >> index d70954b..cf48931 100644 >> --- a/target/i386/cpu.c >> +++ b/target/i386/cpu.c >> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) >> x86_cpu_get_supported_feature_word(w, false); >> uint32_t requested_features = env->features[w]; >> env->features[w] &= host_feat; >> + if (cpu->pv_dedicated && (w == FEAT_KVM)) { >> + env->features[w] |= CPUID_PV_DEDICATED; >> + } > > Why do this trick here instead of just adding "pv-dedicated" to > feature_word_info[FEAT_KVM].feat_names? Actually this hint doesn't depend on KVM, just qemu command-line gives a hint and then guest kernel can recognize it. Is there a nicer proposal in qemu? Paolo? Regards, Wanpeng Li
On 08/02/2018 10:44, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > Add PV_DEDICATED hint cpuid feature bit. Please add a new feature word, since this is not a PV feature but more like a performance hint. Thanks, Paolo > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Eduardo Habkost <ehabkost@redhat.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > target/i386/cpu.c | 4 ++++ > target/i386/cpu.h | 3 +++ > 2 files changed, 7 insertions(+) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index d70954b..cf48931 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) > x86_cpu_get_supported_feature_word(w, false); > uint32_t requested_features = env->features[w]; > env->features[w] &= host_feat; > + if (cpu->pv_dedicated && (w == FEAT_KVM)) { > + env->features[w] |= CPUID_PV_DEDICATED; > + } > cpu->filtered_features[w] = requested_features & ~env->features[w]; > if (cpu->filtered_features[w]) { > rv = 1; > @@ -4682,6 +4685,7 @@ static Property x86_cpu_properties[] = { > false), > DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true), > DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), > + DEFINE_PROP_BOOL("pv-dedicated", X86CPU, pv_dedicated, false), > > /* > * From "Requirements for Implementing the Microsoft > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index f91e37d..8000da5 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -672,6 +672,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; > > #define CPUID_8000_0008_EBX_IBPB (1U << 12) /* Indirect Branch Prediction Barrier */ > > +#define CPUID_PV_DEDICATED (1U << 8) > + > #define CPUID_XSAVE_XSAVEOPT (1U << 0) > #define CPUID_XSAVE_XSAVEC (1U << 1) > #define CPUID_XSAVE_XGETBV1 (1U << 2) > @@ -1276,6 +1278,7 @@ struct X86CPU { > bool expose_kvm; > bool expose_tcg; > bool migratable; > + bool pv_dedicated; > bool max_features; /* Enable all supported features automatically */ > uint32_t apic_id; > >
On 08/02/2018 19:12, Eduardo Habkost wrote: > On Thu, Feb 08, 2018 at 05:44:20PM +0800, Wanpeng Li wrote: >> From: Wanpeng Li <wanpengli@tencent.com> >> >> Add PV_DEDICATED hint cpuid feature bit. >> > [...] >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c >> index d70954b..cf48931 100644 >> --- a/target/i386/cpu.c >> +++ b/target/i386/cpu.c >> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) >> x86_cpu_get_supported_feature_word(w, false); >> uint32_t requested_features = env->features[w]; >> env->features[w] &= host_feat; >> + if (cpu->pv_dedicated && (w == FEAT_KVM)) { >> + env->features[w] |= CPUID_PV_DEDICATED; >> + } > > Why do this trick here instead of just adding "pv-dedicated" to > feature_word_info[FEAT_KVM].feat_names? I think because it can be added independent of KVM_GET_SUPPORTED_CPUID. Paolo
On Fri, Feb 09, 2018 at 09:41:41AM +0100, Paolo Bonzini wrote: > On 08/02/2018 19:12, Eduardo Habkost wrote: > > On Thu, Feb 08, 2018 at 05:44:20PM +0800, Wanpeng Li wrote: > >> From: Wanpeng Li <wanpengli@tencent.com> > >> > >> Add PV_DEDICATED hint cpuid feature bit. > >> > > [...] > >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c > >> index d70954b..cf48931 100644 > >> --- a/target/i386/cpu.c > >> +++ b/target/i386/cpu.c > >> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) > >> x86_cpu_get_supported_feature_word(w, false); > >> uint32_t requested_features = env->features[w]; > >> env->features[w] &= host_feat; > >> + if (cpu->pv_dedicated && (w == FEAT_KVM)) { > >> + env->features[w] |= CPUID_PV_DEDICATED; > >> + } > > > > Why do this trick here instead of just adding "pv-dedicated" to > > feature_word_info[FEAT_KVM].feat_names? > > I think because it can be added independent of KVM_GET_SUPPORTED_CPUID. If QEMU knows it can be enabled if outside GET_SUPPORTED_CPUID, kvm_arch_get_supported_cpuid() can return it as supported.
2018-02-09 16:41 GMT+08:00 Paolo Bonzini <bonzini@gnu.org>: > On 08/02/2018 10:44, Wanpeng Li wrote: >> From: Wanpeng Li <wanpengli@tencent.com> >> >> Add PV_DEDICATED hint cpuid feature bit. > > Please add a new feature word, since this is not a PV feature but more > like a performance hint. Do it in v2. Regards, Wanpeng Li > > Thanks, > > Paolo > >> Cc: Paolo Bonzini <pbonzini@redhat.com> >> Cc: Radim Krčmář <rkrcmar@redhat.com> >> Cc: Eduardo Habkost <ehabkost@redhat.com> >> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> >> --- >> target/i386/cpu.c | 4 ++++ >> target/i386/cpu.h | 3 +++ >> 2 files changed, 7 insertions(+) >> >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c >> index d70954b..cf48931 100644 >> --- a/target/i386/cpu.c >> +++ b/target/i386/cpu.c >> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) >> x86_cpu_get_supported_feature_word(w, false); >> uint32_t requested_features = env->features[w]; >> env->features[w] &= host_feat; >> + if (cpu->pv_dedicated && (w == FEAT_KVM)) { >> + env->features[w] |= CPUID_PV_DEDICATED; >> + } >> cpu->filtered_features[w] = requested_features & ~env->features[w]; >> if (cpu->filtered_features[w]) { >> rv = 1; >> @@ -4682,6 +4685,7 @@ static Property x86_cpu_properties[] = { >> false), >> DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true), >> DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), >> + DEFINE_PROP_BOOL("pv-dedicated", X86CPU, pv_dedicated, false), >> >> /* >> * From "Requirements for Implementing the Microsoft >> diff --git a/target/i386/cpu.h b/target/i386/cpu.h >> index f91e37d..8000da5 100644 >> --- a/target/i386/cpu.h >> +++ b/target/i386/cpu.h >> @@ -672,6 +672,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; >> >> #define CPUID_8000_0008_EBX_IBPB (1U << 12) /* Indirect Branch Prediction Barrier */ >> >> +#define CPUID_PV_DEDICATED (1U << 8) >> + >> #define CPUID_XSAVE_XSAVEOPT (1U << 0) >> #define CPUID_XSAVE_XSAVEC (1U << 1) >> #define CPUID_XSAVE_XGETBV1 (1U << 2) >> @@ -1276,6 +1278,7 @@ struct X86CPU { >> bool expose_kvm; >> bool expose_tcg; >> bool migratable; >> + bool pv_dedicated; >> bool max_features; /* Enable all supported features automatically */ >> uint32_t apic_id; >> >> >
diff --git a/target/i386/cpu.c b/target/i386/cpu.c index d70954b..cf48931 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) x86_cpu_get_supported_feature_word(w, false); uint32_t requested_features = env->features[w]; env->features[w] &= host_feat; + if (cpu->pv_dedicated && (w == FEAT_KVM)) { + env->features[w] |= CPUID_PV_DEDICATED; + } cpu->filtered_features[w] = requested_features & ~env->features[w]; if (cpu->filtered_features[w]) { rv = 1; @@ -4682,6 +4685,7 @@ static Property x86_cpu_properties[] = { false), DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true), DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), + DEFINE_PROP_BOOL("pv-dedicated", X86CPU, pv_dedicated, false), /* * From "Requirements for Implementing the Microsoft diff --git a/target/i386/cpu.h b/target/i386/cpu.h index f91e37d..8000da5 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -672,6 +672,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; #define CPUID_8000_0008_EBX_IBPB (1U << 12) /* Indirect Branch Prediction Barrier */ +#define CPUID_PV_DEDICATED (1U << 8) + #define CPUID_XSAVE_XSAVEOPT (1U << 0) #define CPUID_XSAVE_XSAVEC (1U << 1) #define CPUID_XSAVE_XGETBV1 (1U << 2) @@ -1276,6 +1278,7 @@ struct X86CPU { bool expose_kvm; bool expose_tcg; bool migratable; + bool pv_dedicated; bool max_features; /* Enable all supported features automatically */ uint32_t apic_id;