| Message ID | 20200302235709.27467-65-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Introduce KVM cpu caps | expand |
Sean Christopherson <sean.j.christopherson@intel.com> writes: > Set SVM feature bits in KVM capabilities if and only if nested=true, KVM > shouldn't advertise features that realistically can't be used. Use > kvm_cpu_cap_has(X86_FEATURE_SVM) to indirectly query "nested" in > svm_set_supported_cpuid() in anticipation of moving CPUID 0x8000000A > adjustments into common x86 code. > > Suggested-by: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > arch/x86/kvm/svm.c | 22 +++++++++++++--------- > 1 file changed, 13 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index f32fc3c03667..8e39dcd3160d 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -1373,21 +1373,21 @@ static __init void svm_set_cpu_caps(void) > if (avic) > kvm_cpu_cap_clear(X86_FEATURE_X2APIC); > > - /* CPUID 0x80000001 */ > - if (nested) > + /* CPUID 0x80000001 and 0x8000000A (SVM features) */ > + if (nested) { > kvm_cpu_cap_set(X86_FEATURE_SVM); > > + if (boot_cpu_has(X86_FEATURE_NRIPS)) > + kvm_cpu_cap_set(X86_FEATURE_NRIPS); > + > + if (npt_enabled) > + kvm_cpu_cap_set(X86_FEATURE_NPT); > + } > + > /* CPUID 0x80000008 */ > if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || > boot_cpu_has(X86_FEATURE_AMD_SSBD)) > kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD); > - > - /* CPUID 0x8000000A */ > - /* Support next_rip if host supports it */ > - kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS); > - > - if (npt_enabled) > - kvm_cpu_cap_set(X86_FEATURE_NPT); > } > > static __init int svm_hardware_setup(void) > @@ -6051,6 +6051,10 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) > { > switch (entry->function) { > case 0x8000000A: > + if (!kvm_cpu_cap_has(X86_FEATURE_SVM)) { > + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > + break; > + } > entry->eax = 1; /* SVM revision 1 */ > entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper > ASID emulation to nested SVM */ Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
On Mon, Mar 2, 2020 at 3:57 PM Sean Christopherson <sean.j.christopherson@intel.com> wrote: > > Set SVM feature bits in KVM capabilities if and only if nested=true, KVM > shouldn't advertise features that realistically can't be used. Use > kvm_cpu_cap_has(X86_FEATURE_SVM) to indirectly query "nested" in > svm_set_supported_cpuid() in anticipation of moving CPUID 0x8000000A > adjustments into common x86 code. Why not go ahead and report the SVM feature bits regardless of "nested," and lock SVM off in VM_CR when nested=false? That would be more like hardware behavior.
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index f32fc3c03667..8e39dcd3160d 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1373,21 +1373,21 @@ static __init void svm_set_cpu_caps(void) if (avic) kvm_cpu_cap_clear(X86_FEATURE_X2APIC); - /* CPUID 0x80000001 */ - if (nested) + /* CPUID 0x80000001 and 0x8000000A (SVM features) */ + if (nested) { kvm_cpu_cap_set(X86_FEATURE_SVM); + if (boot_cpu_has(X86_FEATURE_NRIPS)) + kvm_cpu_cap_set(X86_FEATURE_NRIPS); + + if (npt_enabled) + kvm_cpu_cap_set(X86_FEATURE_NPT); + } + /* CPUID 0x80000008 */ if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || boot_cpu_has(X86_FEATURE_AMD_SSBD)) kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD); - - /* CPUID 0x8000000A */ - /* Support next_rip if host supports it */ - kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS); - - if (npt_enabled) - kvm_cpu_cap_set(X86_FEATURE_NPT); } static __init int svm_hardware_setup(void) @@ -6051,6 +6051,10 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) { switch (entry->function) { case 0x8000000A: + if (!kvm_cpu_cap_has(X86_FEATURE_SVM)) { + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; + break; + } entry->eax = 1; /* SVM revision 1 */ entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper ASID emulation to nested SVM */
Set SVM feature bits in KVM capabilities if and only if nested=true, KVM shouldn't advertise features that realistically can't be used. Use kvm_cpu_cap_has(X86_FEATURE_SVM) to indirectly query "nested" in svm_set_supported_cpuid() in anticipation of moving CPUID 0x8000000A adjustments into common x86 code. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/svm.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)