[PATCH 3/7] KVM: SVM: Add VNMI support in get/set_nmi_mask

[Santosh Shukla <santosh.shukla@amd.com>]

VMCB intr_ctrl bit12 (V_NMI_MASK) is set by the processor when handling
NMI in guest and is cleared after the NMI is handled. Treat V_NMI_MASK as
read-only in the hypervisor and do not populate set accessors.

Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
---
 arch/x86/kvm/svm/svm.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 860f28c668bd..d67a54517d95 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -323,6 +323,16 @@ static int is_external_interrupt(u32 info)
 	return info == (SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR);
 }
 
+static bool is_vnmi_enabled(struct vmcb *vmcb)
+{
+	return vnmi && (vmcb->control.int_ctl & V_NMI_ENABLE);
+}
+
+static bool is_vnmi_mask_set(struct vmcb *vmcb)
+{
+	return !!(vmcb->control.int_ctl & V_NMI_MASK);
+}
+
 static u32 svm_get_interrupt_shadow(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -3502,13 +3512,21 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
 
 static bool svm_get_nmi_mask(struct kvm_vcpu *vcpu)
 {
-	return !!(vcpu->arch.hflags & HF_NMI_MASK);
+	struct vcpu_svm *svm = to_svm(vcpu);
+
+	if (is_vnmi_enabled(svm->vmcb))
+		return is_vnmi_mask_set(svm->vmcb);
+	else
+		return !!(vcpu->arch.hflags & HF_NMI_MASK);
 }
 
 static void svm_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
+	if (is_vnmi_enabled(svm->vmcb))
+		return;
+
 	if (masked) {
 		vcpu->arch.hflags |= HF_NMI_MASK;
 		if (!sev_es_guest(vcpu->kvm))
-- 
2.25.1