[PATCH v3 18/57] KVM: x86: Zero out PV features cache when the CPUID leaf is not present

[Sean Christopherson]

Clear KVM's PV feature cache prior when processing a new guest CPUID so
that KVM doesn't keep a stale cache entry if userspace does KVM_SET_CPUID2
multiple times, once with a PV features entry, and a second time without.

Fixes: 66570e966dd9 ("kvm: x86: only provide PV features if enabled in guest's CPUID")
Cc: Oliver Upton <oliver.upton@xxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/kvm/cpuid.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 27919c8f438b..a94234637e09 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -251,6 +251,8 @@ void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpuid_entry2 *best = kvm_find_kvm_cpuid_features(vcpu);
 
+	vcpu->arch.pv_cpuid.features = 0;
+
 	/*
 	 * save the feature bitmap to avoid cpuid lookup for every PV
 	 * operation
-- 
2.47.0.338.g60cca15819-goog