| Message ID | 1566376002-17121-3-git-send-email-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: fixes for speculation bug feature reporting | expand |
On Wed, Aug 21, 2019 at 1:27 AM Paolo Bonzini <pbonzini@redhat.com> wrote: > > Even though it is preferrable to use SPEC_CTRL (represented by > X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always > supported anyway because otherwise it would be impossible to > migrate from old to new CPUs. Make this apparent in the > result of KVM_GET_SUPPORTED_CPUID as well. > > While at it, reuse X86_FEATURE_* constants for the SVM leaf too. > > However, we need to hide the bit on Intel processors, so move > the setting to svm_set_supported_cpuid. > > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Reported-by: Eduardo Habkost <ehabkost@redhat.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Jim Mattson <jmattson@google.com>
On Wed, Aug 21, 2019 at 10:26:41AM +0200, Paolo Bonzini wrote: > Even though it is preferrable to use SPEC_CTRL (represented by > X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always > supported anyway because otherwise it would be impossible to > migrate from old to new CPUs. Make this apparent in the > result of KVM_GET_SUPPORTED_CPUID as well. > > While at it, reuse X86_FEATURE_* constants for the SVM leaf too. > > However, we need to hide the bit on Intel processors, so move > the setting to svm_set_supported_cpuid. > > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Thank you!
On Wed, Aug 21, 2019 at 10:26:41AM +0200, Paolo Bonzini wrote: > Even though it is preferrable to use SPEC_CTRL (represented by > X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always > supported anyway because otherwise it would be impossible to > migrate from old to new CPUs. Make this apparent in the > result of KVM_GET_SUPPORTED_CPUID as well. > > While at it, reuse X86_FEATURE_* constants for the SVM leaf too. > > However, we need to hide the bit on Intel processors, so move > the setting to svm_set_supported_cpuid. > > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Reported-by: Eduardo Habkost <ehabkost@redhat.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- [...] > @@ -5944,6 +5944,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) > if (nested) > entry->ecx |= (1 << 2); /* Set SVM bit */ > break; > + case 0x80000008: > + if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || > + boot_cpu_has(X86_FEATURE_AMD_SSBD)) > + entry->ebx |= F(VIRT_SSBD); > + break; Wasn't the old code at arch/x86/kvm/cpuid.c:__do_cpuid_func() supposed to be deleted? /* * The preference is to use SPEC CTRL MSR instead of the * VIRT_SPEC MSR. */ if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) && !boot_cpu_has(X86_FEATURE_AMD_SSBD)) entry->ebx |= F(VIRT_SSBD);
On 02/10/19 00:16, Eduardo Habkost wrote: > Wasn't the old code at arch/x86/kvm/cpuid.c:__do_cpuid_func() > supposed to be deleted? > > /* > * The preference is to use SPEC CTRL MSR instead of the > * VIRT_SPEC MSR. > */ > if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) && > !boot_cpu_has(X86_FEATURE_AMD_SSBD)) > entry->ebx |= F(VIRT_SSBD); Yeah, it's harmless but also useless. Paolo
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index e3d3b2128f2b..c5120a9519f3 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -68,10 +68,8 @@ #define SEG_TYPE_LDT 2 #define SEG_TYPE_BUSY_TSS16 3 -#define SVM_FEATURE_NPT (1 << 0) #define SVM_FEATURE_LBRV (1 << 1) #define SVM_FEATURE_SVML (1 << 2) -#define SVM_FEATURE_NRIP (1 << 3) #define SVM_FEATURE_TSC_RATE (1 << 4) #define SVM_FEATURE_VMCB_CLEAN (1 << 5) #define SVM_FEATURE_FLUSH_ASID (1 << 6) @@ -5933,6 +5931,8 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu) guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC); } +#define F(x) bit(X86_FEATURE_##x) + static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) { switch (func) { @@ -5944,6 +5944,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) if (nested) entry->ecx |= (1 << 2); /* Set SVM bit */ break; + case 0x80000008: + if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || + boot_cpu_has(X86_FEATURE_AMD_SSBD)) + entry->ebx |= F(VIRT_SSBD); + break; case 0x8000000A: entry->eax = 1; /* SVM revision 1 */ entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper @@ -5954,11 +5959,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) /* Support next_rip if host supports it */ if (boot_cpu_has(X86_FEATURE_NRIPS)) - entry->edx |= SVM_FEATURE_NRIP; + entry->edx |= F(NRIPS); /* Support NPT for the guest if enabled */ if (npt_enabled) - entry->edx |= SVM_FEATURE_NPT; + entry->edx |= F(NPT); break; case 0x8000001F:
Even though it is preferrable to use SPEC_CTRL (represented by X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always supported anyway because otherwise it would be impossible to migrate from old to new CPUs. Make this apparent in the result of KVM_GET_SUPPORTED_CPUID as well. While at it, reuse X86_FEATURE_* constants for the SVM leaf too. However, we need to hide the bit on Intel processors, so move the setting to svm_set_supported_cpuid. Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reported-by: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/svm.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)