| Message ID | 20230124194519.2893234-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86: KVM: Add common feature flag for AMD's PSFD | expand |
On 1/24/23 20:45, Sean Christopherson wrote: > Use a common X86_FEATURE_* flag for AMD's PSFD, and suppress it from > /proc/cpuinfo via the standard method of an empty string instead of > hacking in a one-off "private" #define in KVM. The request that led to > KVM defining its own flag was really just that the feature not show up > in /proc/cpuinfo, and additional patches+discussions in the interim have > clarified that defining flags in cpufeatures.h purely so that KVM can > advertise features to userspace is ok so long as the kernel already uses > a word to track the associated CPUID leaf. > > No functional change intended. > > Link: https://lore.kernel.org/all/d1b1e0da-29f0-c443-6c86-9549bbe1c79d@redhat.como > Link: https://lore.kernel.org/all/YxGZH7aOXQF7Pu5q@nazgul.tnic > Link: https://lore.kernel.org/all/Y3O7UYWfOLfJkwM%2F@zn.tnic > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/include/asm/cpufeatures.h | 1 + > arch/x86/kvm/cpuid.c | 8 +------- > 2 files changed, 2 insertions(+), 7 deletions(-) Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h > index 61012476d66e..2acaebc7bb76 100644 > --- a/arch/x86/include/asm/cpufeatures.h > +++ b/arch/x86/include/asm/cpufeatures.h > @@ -330,6 +330,7 @@ > #define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */ > #define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */ > #define X86_FEATURE_CPPC (13*32+27) /* Collaborative Processor Performance Control */ > +#define X86_FEATURE_AMD_PSFD (13*32+28) /* "" Predictive Store Forwarding Disable */ > #define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */ > #define X86_FEATURE_BRS (13*32+31) /* Branch Sampling available */ > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 2a9f1e200dbc..fb2b0e3ecce1 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -59,12 +59,6 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted) > return ret; > } > > -/* > - * This one is tied to SSB in the user API, and not > - * visible in /proc/cpuinfo. > - */ > -#define KVM_X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */ > - > #define F feature_bit > > /* Scattered Flag - For features that are scattered by cpufeatures.h. */ > @@ -710,7 +704,7 @@ void kvm_set_cpu_caps(void) > F(CLZERO) | F(XSAVEERPTR) | > F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) | > F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) | > - __feature_bit(KVM_X86_FEATURE_AMD_PSFD) > + F(AMD_PSFD) > ); > > /* > > base-commit: 7cb79f433e75b05d1635aefaa851cfcd1cb7dc4f
On Tue, 24 Jan 2023 19:45:19 +0000, Sean Christopherson wrote: > Use a common X86_FEATURE_* flag for AMD's PSFD, and suppress it from > /proc/cpuinfo via the standard method of an empty string instead of > hacking in a one-off "private" #define in KVM. The request that led to > KVM defining its own flag was really just that the feature not show up > in /proc/cpuinfo, and additional patches+discussions in the interim have > clarified that defining flags in cpufeatures.h purely so that KVM can > advertise features to userspace is ok so long as the kernel already uses > a word to track the associated CPUID leaf. > > [...] Applied to kvm-x86 misc, thanks! [1/1] x86: KVM: Add common feature flag for AMD's PSFD https://github.com/kvm-x86/linux/commit/3d8f61bf8bcd -- https://github.com/kvm-x86/linux/tree/next https://github.com/kvm-x86/linux/tree/fixes
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 61012476d66e..2acaebc7bb76 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -330,6 +330,7 @@ #define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */ #define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */ #define X86_FEATURE_CPPC (13*32+27) /* Collaborative Processor Performance Control */ +#define X86_FEATURE_AMD_PSFD (13*32+28) /* "" Predictive Store Forwarding Disable */ #define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */ #define X86_FEATURE_BRS (13*32+31) /* Branch Sampling available */ diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 2a9f1e200dbc..fb2b0e3ecce1 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -59,12 +59,6 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted) return ret; } -/* - * This one is tied to SSB in the user API, and not - * visible in /proc/cpuinfo. - */ -#define KVM_X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */ - #define F feature_bit /* Scattered Flag - For features that are scattered by cpufeatures.h. */ @@ -710,7 +704,7 @@ void kvm_set_cpu_caps(void) F(CLZERO) | F(XSAVEERPTR) | F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) | F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) | - __feature_bit(KVM_X86_FEATURE_AMD_PSFD) + F(AMD_PSFD) ); /*
Use a common X86_FEATURE_* flag for AMD's PSFD, and suppress it from /proc/cpuinfo via the standard method of an empty string instead of hacking in a one-off "private" #define in KVM. The request that led to KVM defining its own flag was really just that the feature not show up in /proc/cpuinfo, and additional patches+discussions in the interim have clarified that defining flags in cpufeatures.h purely so that KVM can advertise features to userspace is ok so long as the kernel already uses a word to track the associated CPUID leaf. No functional change intended. Link: https://lore.kernel.org/all/d1b1e0da-29f0-c443-6c86-9549bbe1c79d@redhat.como Link: https://lore.kernel.org/all/YxGZH7aOXQF7Pu5q@nazgul.tnic Link: https://lore.kernel.org/all/Y3O7UYWfOLfJkwM%2F@zn.tnic Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kvm/cpuid.c | 8 +------- 2 files changed, 2 insertions(+), 7 deletions(-) base-commit: 7cb79f433e75b05d1635aefaa851cfcd1cb7dc4f