| Message ID | 20220708144223.610080-7-vkuznets@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: Support updated eVMCSv1 revision + use vmcs_config for L1 VMX MSRs | expand |
On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote: > KVM has to check guest visible HYPERV_CPUID_NESTED_FEATURES.EBX CPUID > leaf to know with Enlightened VMCS definition to use (original or 2022 > update). Cache the leaf along with other Hyper-V CPUID feature leaves > to make the check quick. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > --- > arch/x86/include/asm/kvm_host.h | 2 ++ > arch/x86/kvm/hyperv.c | 9 +++++++++ > 2 files changed, 11 insertions(+) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index de5a149d0971..077ec9cf3169 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -616,6 +616,8 @@ struct kvm_vcpu_hv { > u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */ > u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */ > u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */ > + u32 nested_eax; /* HYPERV_CPUID_NESTED_FEATURES.EAX */ > + u32 nested_ebx; /* HYPERV_CPUID_NESTED_FEATURES.EBX */ > } cpuid_cache; > }; > > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index e08189211d9a..b666902da4d9 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -2030,6 +2030,15 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu) > hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax; > else > hv_vcpu->cpuid_cache.syndbg_cap_eax = 0; > + > + entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_NESTED_FEATURES, 0); > + if (entry) { > + hv_vcpu->cpuid_cache.nested_eax = entry->eax; > + hv_vcpu->cpuid_cache.nested_ebx = entry->ebx; > + } else { > + hv_vcpu->cpuid_cache.nested_eax = 0; > + hv_vcpu->cpuid_cache.nested_ebx = 0; > + } > } > > int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce) Small Nitpick: If I understand correctly, the kvm_find_cpuid_entry can fail if the userspace didn't provide the cpuid entry. Since the code that deals with failback is now repeated 3 times, how about some wrapper function that will return all zeros for a non present cpuid entry? That can be done later of course, so Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky
Maxim Levitsky <mlevitsk@redhat.com> writes: > On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote: >> KVM has to check guest visible HYPERV_CPUID_NESTED_FEATURES.EBX CPUID >> leaf to know with Enlightened VMCS definition to use (original or 2022 >> update). Cache the leaf along with other Hyper-V CPUID feature leaves >> to make the check quick. >> >> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> >> --- >> arch/x86/include/asm/kvm_host.h | 2 ++ >> arch/x86/kvm/hyperv.c | 9 +++++++++ >> 2 files changed, 11 insertions(+) >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index de5a149d0971..077ec9cf3169 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -616,6 +616,8 @@ struct kvm_vcpu_hv { >> u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */ >> u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */ >> u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */ >> + u32 nested_eax; /* HYPERV_CPUID_NESTED_FEATURES.EAX */ >> + u32 nested_ebx; /* HYPERV_CPUID_NESTED_FEATURES.EBX */ >> } cpuid_cache; >> }; >> >> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c >> index e08189211d9a..b666902da4d9 100644 >> --- a/arch/x86/kvm/hyperv.c >> +++ b/arch/x86/kvm/hyperv.c >> @@ -2030,6 +2030,15 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu) >> hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax; >> else >> hv_vcpu->cpuid_cache.syndbg_cap_eax = 0; >> + >> + entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_NESTED_FEATURES, 0); >> + if (entry) { >> + hv_vcpu->cpuid_cache.nested_eax = entry->eax; >> + hv_vcpu->cpuid_cache.nested_ebx = entry->ebx; >> + } else { >> + hv_vcpu->cpuid_cache.nested_eax = 0; >> + hv_vcpu->cpuid_cache.nested_ebx = 0; >> + } >> } >> >> int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce) > > > Small Nitpick: > > If I understand correctly, the kvm_find_cpuid_entry can fail if the userspace didn't provide the > cpuid entry. > > Since the code that deals with failback is now repeated 3 times, how about some wrapper function that > will return all zeros for a non present cpuid entry? I've opted for wiping the whole hv_vcpu->cpuid_cache with memset(), this way we don't even need a new helper.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index de5a149d0971..077ec9cf3169 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -616,6 +616,8 @@ struct kvm_vcpu_hv { u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */ u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */ u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */ + u32 nested_eax; /* HYPERV_CPUID_NESTED_FEATURES.EAX */ + u32 nested_ebx; /* HYPERV_CPUID_NESTED_FEATURES.EBX */ } cpuid_cache; }; diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index e08189211d9a..b666902da4d9 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -2030,6 +2030,15 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu) hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax; else hv_vcpu->cpuid_cache.syndbg_cap_eax = 0; + + entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_NESTED_FEATURES, 0); + if (entry) { + hv_vcpu->cpuid_cache.nested_eax = entry->eax; + hv_vcpu->cpuid_cache.nested_ebx = entry->ebx; + } else { + hv_vcpu->cpuid_cache.nested_eax = 0; + hv_vcpu->cpuid_cache.nested_ebx = 0; + } } int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)
KVM has to check guest visible HYPERV_CPUID_NESTED_FEATURES.EBX CPUID leaf to know with Enlightened VMCS definition to use (original or 2022 update). Cache the leaf along with other Hyper-V CPUID feature leaves to make the check quick. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/hyperv.c | 9 +++++++++ 2 files changed, 11 insertions(+)