When updating guest CPUID entries to emulate runtime behavior, e.g. when
the guest enables a CR4-based feature that is tied to a CPUID flag, also
update the vCPU's cpu_caps accordingly. This will allow replacing all
usage of guest_cpuid_has() with guest_cpu_cap_has().
Note, this relies on kvm_set_cpuid() taking a snapshot of cpu_caps before
invoking kvm_update_cpuid_runtime(), i.e. when KVM is updating CPUID
entries that *may* become the vCPU's CPUID, so that unwinding to the old
cpu_caps is possible if userspace tries to set bogus CPUID information.
Note #2, none of the features in question use guest_cpu_cap_has() at this
time, i.e. aside from settings bits in cpu_caps, this is a glorified nop.
Cc: Yang Weijiang <weijiang.yang@xxxxxxxxx>
Cc: Robert Hoo <robert.hoo.linux@xxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 552e65ba5efa..1424a9d4eb17 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -330,28 +330,38 @@ static u64 cpuid_get_supported_xcr0(struct kvm_vcpu *vcpu)
return (best->eax | ((u64)best->edx << 32)) & kvm_caps.supported_xcr0;
}
+static __always_inline void kvm_update_feature_runtime(struct kvm_vcpu *vcpu,
+ struct kvm_cpuid_entry2 *entry,
+ unsigned int x86_feature,
+ bool has_feature)
+{
+ cpuid_entry_change(entry, x86_feature, has_feature);
+ guest_cpu_cap_change(vcpu, x86_feature, has_feature);
+}
+
void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
best = kvm_find_cpuid_entry(vcpu, 1);
if (best) {
- cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
- kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE));
+ kvm_update_feature_runtime(vcpu, best, X86_FEATURE_OSXSAVE,
+ kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE));
- cpuid_entry_change(best, X86_FEATURE_APIC,
- vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
+ kvm_update_feature_runtime(vcpu, best, X86_FEATURE_APIC,
+ vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT))
- cpuid_entry_change(best, X86_FEATURE_MWAIT,
- vcpu->arch.ia32_misc_enable_msr &
- MSR_IA32_MISC_ENABLE_MWAIT);
+ kvm_update_feature_runtime(vcpu, best, X86_FEATURE_MWAIT,
+ vcpu->arch.ia32_misc_enable_msr &
+ MSR_IA32_MISC_ENABLE_MWAIT);
}
best = kvm_find_cpuid_entry_index(vcpu, 7, 0);
if (best)
- cpuid_entry_change(best, X86_FEATURE_OSPKE,
- kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE));
+ kvm_update_feature_runtime(vcpu, best, X86_FEATURE_OSPKE,
+ kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE));
+
best = kvm_find_cpuid_entry_index(vcpu, 0xD, 0);
if (best)
--
2.45.0.215.g3402c0e53f-goog
