| Message ID | 20180410115711.GE29865@localhost.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10/04/2018 13:57, Eduardo Habkost wrote: > On Tue, Apr 10, 2018 at 05:13:21PM +0800, Wanpeng Li wrote: >> Hi Eduardo, >> 2018-03-09 22:16 GMT+08:00 Eduardo Habkost <ehabkost@redhat.com>: >>> On Fri, Feb 09, 2018 at 06:15:25AM -0800, Wanpeng Li wrote: >>>> From: Wanpeng Li <wanpengli@tencent.com> >>>> >>>> Add KVM_HINTS_DEDICATED performance hint, guest checks this feature bit >>>> to determine if they run on dedicated vCPUs, allowing optimizations such >>>> as usage of qspinlocks. >>>> >>>> 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> >>>> --- >>>> v1 -> v2: >>>> * add a new feature word >>>> >>>> target/i386/cpu.c | 14 ++++++++++++++ >>>> target/i386/cpu.h | 3 +++ >>>> target/i386/kvm.c | 4 ++++ >>>> 3 files changed, 21 insertions(+) >>>> >>>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c >>>> index d70954b..e2974ad 100644 >>>> --- a/target/i386/cpu.c >>>> +++ b/target/i386/cpu.c >>>> @@ -358,6 +358,20 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { >>>> .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EAX, >>>> .tcg_features = TCG_KVM_FEATURES, >>>> }, >>>> + [FEAT_KVM_HINTS] = { >>>> + .feat_names = { >>>> + "hint-dedicated", NULL, NULL, NULL, >>> >>> I suggest naming it "kvm-hint-dedicated", to indicate it's >>> KVM-specific. >> >> I found this feature is enabled by default w/o kvm-hint-dedicated >> parameter, any idea how to make it disabled by default? > > You mean on "-cpu host", right? > > The assumption in most of the code is that anything enabled on > GET_SUPPORTED_CPUID should be enabled on "-cpu host". This > shouldn't be the case for FEAT_KVM_HINTS. > > Untested fix below. > > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> > --- > target/i386/cpu.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index 1a6b082b6f..a20fe26573 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -295,6 +295,8 @@ typedef struct FeatureWordInfo { > uint32_t tcg_features; /* Feature flags supported by TCG */ > uint32_t unmigratable_flags; /* Feature flags known to be unmigratable */ > uint32_t migratable_flags; /* Feature flags known to be migratable */ > + /* Features that shouldn't be auto-enabled by "-cpu host" */ > + uint32_t no_autoenable_flags; > } FeatureWordInfo; > > static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { > @@ -400,6 +402,11 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { > }, > .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EDX, > .tcg_features = TCG_KVM_FEATURES, > + /* > + * KVM hints aren't auto-enabled by -cpu host, they need to be > + * explicitly enabled in the command-line. > + */ > + .no_autoenable_flags = ~0U, > }, > [FEAT_HYPERV_EAX] = { > .feat_names = { > @@ -4062,7 +4069,8 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp) > */ > env->features[w] |= > x86_cpu_get_supported_feature_word(w, cpu->migratable) & > - ~env->user_features[w]; > + ~env->user_features[w] & \ > + ~feature_word_info[w].no_autoenable_flags; > } > } > > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 1a6b082b6f..a20fe26573 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -295,6 +295,8 @@ typedef struct FeatureWordInfo { uint32_t tcg_features; /* Feature flags supported by TCG */ uint32_t unmigratable_flags; /* Feature flags known to be unmigratable */ uint32_t migratable_flags; /* Feature flags known to be migratable */ + /* Features that shouldn't be auto-enabled by "-cpu host" */ + uint32_t no_autoenable_flags; } FeatureWordInfo; static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { @@ -400,6 +402,11 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { }, .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EDX, .tcg_features = TCG_KVM_FEATURES, + /* + * KVM hints aren't auto-enabled by -cpu host, they need to be + * explicitly enabled in the command-line. + */ + .no_autoenable_flags = ~0U, }, [FEAT_HYPERV_EAX] = { .feat_names = { @@ -4062,7 +4069,8 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp) */ env->features[w] |= x86_cpu_get_supported_feature_word(w, cpu->migratable) & - ~env->user_features[w]; + ~env->user_features[w] & \ + ~feature_word_info[w].no_autoenable_flags; } }