KVM: X86: Fix failure to boost kernel lock holder candidate in SEV-ES guests

Commit f1c6366e3043 ("KVM: SVM: Add required changes to support intercepts under
SEV-ES") prevents hypervisor accesses guest register state when the guest is
running under SEV-ES. The initial value of vcpu->arch.guest_state_protected
is false, it will not be updated in preemption notifiers after this commit which
means that the kernel spinlock lock holder will always be skipped to boost. Let's
fix it by always treating preempted is in the guest kernel mode, false positive
is better than skip completely.

Fixes: f1c6366e3043 (KVM: SVM: Add required changes to support intercepts under SEV-ES)
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1619080459-30032-1-git-send-email-wanpengli@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5ddb90470f1f9d1fc33d5668d3020501f5f8f7b1..4c9c9592a4374fd61406397f9ed41b9011ed06f9 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11141,6 +11141,9 @@ bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu)
 
 bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 {
+       if (vcpu->arch.guest_state_protected)
+               return true;
+
        return vcpu->arch.preempted_in_kernel;
 }