* [PATCH 1/3] KVM: x86: Insert "AMD" in KVM_X86_FEATURE_PSFD @ 2022-08-26 21:00 Jim Mattson 2022-08-26 21:00 ` [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 Jim Mattson 2022-08-26 21:00 ` [PATCH 3/3] KVM: x86: Expose Predictive Store Forwarding Disable on Intel parts Jim Mattson 0 siblings, 2 replies; 5+ messages in thread From: Jim Mattson @ 2022-08-26 21:00 UTC (permalink / raw) To: kvm, pbonzini; +Cc: Jim Mattson, Babu Moger Intel and AMD have separate CPUID bits for each SPEC_CTRL bit. In the case of every bit other than PFSD, the Intel CPUID bit has no vendor name qualifier, but the AMD CPUID bit does. For consistency, rename KVM_X86_FEATURE_PSFD to KVM_X86_FEATURE_AMD_PSFD. No functional change intended. Signed-off-by: Jim Mattson <jmattson@google.com> Cc: Babu Moger <Babu.Moger@amd.com> --- arch/x86/kvm/cpuid.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 75dcf7a72605..07be45c5bb93 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -62,7 +62,7 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted) * This one is tied to SSB in the user API, and not * visible in /proc/cpuinfo. */ -#define KVM_X86_FEATURE_PSFD (13*32+28) /* Predictive Store Forwarding Disable */ +#define KVM_X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */ #define F feature_bit #define SF(name) (boot_cpu_has(X86_FEATURE_##name) ? F(name) : 0) @@ -673,7 +673,7 @@ 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_PSFD) + __feature_bit(KVM_X86_FEATURE_AMD_PSFD) ); /* -- 2.37.2.672.g94769d06f0-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 2022-08-26 21:00 [PATCH 1/3] KVM: x86: Insert "AMD" in KVM_X86_FEATURE_PSFD Jim Mattson @ 2022-08-26 21:00 ` Jim Mattson 2022-08-26 23:54 ` Sean Christopherson 2022-08-26 21:00 ` [PATCH 3/3] KVM: x86: Expose Predictive Store Forwarding Disable on Intel parts Jim Mattson 1 sibling, 1 reply; 5+ messages in thread From: Jim Mattson @ 2022-08-26 21:00 UTC (permalink / raw) To: kvm, pbonzini; +Cc: Jim Mattson, Sean Christopherson Previously, KVM reported support for CPUID.(EAX=7,ECX=1) only if the maximum leaf 7 index on the host was exactly 1. A recent microcode patch for Ice Lake raised the maximum leaf 7 index from 0 to 2, skipping right over 1. Though that patch left CPUID.(EAX=7,ECX=1) filled with zeros on Ice Lake, it nonetheless exposed this bug. Report CPUID.(EAX=7,ECX=1) support if the maximum leaf 7 index on the host is at least 1. Cc: Sean Christopherson <seanjc@google.com> Fixes: bcf600ca8d21 ("KVM: x86: Remove the unnecessary loop on CPUID 0x7 sub-leafs") Signed-off-by: Jim Mattson <jmattson@google.com> --- arch/x86/kvm/cpuid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 07be45c5bb93..64cdabb3cb2c 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -886,7 +886,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) cpuid_entry_override(entry, CPUID_7_EDX); /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */ - if (entry->eax == 1) { + if (entry->eax >= 1) { entry = do_host_cpuid(array, function, 1); if (!entry) goto out; -- 2.37.2.672.g94769d06f0-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 2022-08-26 21:00 ` [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 Jim Mattson @ 2022-08-26 23:54 ` Sean Christopherson 2022-08-27 16:51 ` Jim Mattson 0 siblings, 1 reply; 5+ messages in thread From: Sean Christopherson @ 2022-08-26 23:54 UTC (permalink / raw) To: Jim Mattson; +Cc: kvm, pbonzini On Fri, Aug 26, 2022, Jim Mattson wrote: > Previously, KVM reported support for CPUID.(EAX=7,ECX=1) only if the > maximum leaf 7 index on the host was exactly 1. A recent microcode > patch for Ice Lake raised the maximum leaf 7 index from 0 to 2, > skipping right over 1. Though that patch left CPUID.(EAX=7,ECX=1) > filled with zeros on Ice Lake, it nonetheless exposed this bug. > > Report CPUID.(EAX=7,ECX=1) support if the maximum leaf 7 index on the > host is at least 1. > > Cc: Sean Christopherson <seanjc@google.com> > Fixes: bcf600ca8d21 ("KVM: x86: Remove the unnecessary loop on CPUID 0x7 sub-leafs") > Signed-off-by: Jim Mattson <jmattson@google.com> > --- > arch/x86/kvm/cpuid.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 07be45c5bb93..64cdabb3cb2c 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -886,7 +886,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > cpuid_entry_override(entry, CPUID_7_EDX); > > /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */ > - if (entry->eax == 1) { > + if (entry->eax >= 1) { But as the comment says, above this is: entry->eax = min(entry->eax, 1u); ... /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */ if (entry->eax == 1) { What am I missing? ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 2022-08-26 23:54 ` Sean Christopherson @ 2022-08-27 16:51 ` Jim Mattson 0 siblings, 0 replies; 5+ messages in thread From: Jim Mattson @ 2022-08-27 16:51 UTC (permalink / raw) To: Sean Christopherson; +Cc: kvm, pbonzini On Fri, Aug 26, 2022 at 4:54 PM Sean Christopherson <seanjc@google.com> wrote: > > On Fri, Aug 26, 2022, Jim Mattson wrote: > > Previously, KVM reported support for CPUID.(EAX=7,ECX=1) only if the > > maximum leaf 7 index on the host was exactly 1. A recent microcode > > patch for Ice Lake raised the maximum leaf 7 index from 0 to 2, > > skipping right over 1. Though that patch left CPUID.(EAX=7,ECX=1) > > filled with zeros on Ice Lake, it nonetheless exposed this bug. > > > > Report CPUID.(EAX=7,ECX=1) support if the maximum leaf 7 index on the > > host is at least 1. > > > > Cc: Sean Christopherson <seanjc@google.com> > > Fixes: bcf600ca8d21 ("KVM: x86: Remove the unnecessary loop on CPUID 0x7 sub-leafs") > > Signed-off-by: Jim Mattson <jmattson@google.com> > > --- > > arch/x86/kvm/cpuid.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > > index 07be45c5bb93..64cdabb3cb2c 100644 > > --- a/arch/x86/kvm/cpuid.c > > +++ b/arch/x86/kvm/cpuid.c > > @@ -886,7 +886,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > > cpuid_entry_override(entry, CPUID_7_EDX); > > > > /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */ > > - if (entry->eax == 1) { > > + if (entry->eax >= 1) { > > But as the comment says, above this is: > > entry->eax = min(entry->eax, 1u); > > ... > > /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */ > if (entry->eax == 1) { > > What am I missing? It's not you; it's me. There's no bug here. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 3/3] KVM: x86: Expose Predictive Store Forwarding Disable on Intel parts 2022-08-26 21:00 [PATCH 1/3] KVM: x86: Insert "AMD" in KVM_X86_FEATURE_PSFD Jim Mattson 2022-08-26 21:00 ` [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 Jim Mattson @ 2022-08-26 21:00 ` Jim Mattson 1 sibling, 0 replies; 5+ messages in thread From: Jim Mattson @ 2022-08-26 21:00 UTC (permalink / raw) To: kvm, pbonzini; +Cc: Jim Mattson Intel enumerates support for PSFD in CPUID.(EAX=7,ECX=2):EDX.PSFD[bit 0]. Report support for this feature in KVM if it is available on the host. Presumably, this feature bit, like its AMD counterpart, is not welcome in cpufeatures.h, so add a local definition of this feature in KVM. Signed-off-by: Jim Mattson <jmattson@google.com> --- arch/x86/kvm/cpuid.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 64cdabb3cb2c..b5af9e451bef 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -62,6 +62,7 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted) * This one is tied to SSB in the user API, and not * visible in /proc/cpuinfo. */ +#define KVM_X86_FEATURE_PSFD 0 /* Predictive Store Forwarding Disable */ #define KVM_X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */ #define F feature_bit @@ -677,9 +678,9 @@ void kvm_set_cpu_caps(void) ); /* - * AMD has separate bits for each SPEC_CTRL bit. - * arch/x86/kernel/cpu/bugs.c is kind enough to - * record that in cpufeatures so use them. + * AMD has separate bits for each SPEC_CTRL bit. Except for + * PSFD, arch/x86/kernel/cpu/bugs.c is kind enough to record + * that in cpufeatures so use them. */ if (boot_cpu_has(X86_FEATURE_IBPB)) kvm_cpu_cap_set(X86_FEATURE_AMD_IBPB); @@ -880,13 +881,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) break; /* function 7 has additional index. */ case 7: - entry->eax = min(entry->eax, 1u); + /* KVM only supports leaf 7 indices 0 through 2. */ + max_idx = entry->eax = min(entry->eax, 2u); cpuid_entry_override(entry, CPUID_7_0_EBX); cpuid_entry_override(entry, CPUID_7_ECX); cpuid_entry_override(entry, CPUID_7_EDX); - /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */ - if (entry->eax >= 1) { + if (max_idx >= 1) { entry = do_host_cpuid(array, function, 1); if (!entry) goto out; @@ -896,6 +897,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->ecx = 0; entry->edx = 0; } + if (max_idx >= 2) { + entry = do_host_cpuid(array, function, 2); + if (!entry) + goto out; + + entry->eax = 0; + entry->ebx = 0; + entry->ecx = 0; + entry->edx &= BIT(KVM_X86_FEATURE_PSFD); + } break; case 9: break; -- 2.37.2.672.g94769d06f0-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-08-27 16:51 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2022-08-26 21:00 [PATCH 1/3] KVM: x86: Insert "AMD" in KVM_X86_FEATURE_PSFD Jim Mattson 2022-08-26 21:00 ` [PATCH 2/3] KVM: x86: Report CPUID.7.1 support on CPUs with CPUID.7 indices > 1 Jim Mattson 2022-08-26 23:54 ` Sean Christopherson 2022-08-27 16:51 ` Jim Mattson 2022-08-26 21:00 ` [PATCH 3/3] KVM: x86: Expose Predictive Store Forwarding Disable on Intel parts Jim Mattson
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