[PATCHv2 3/7] KVM: SVM: Add VNMI support in get/set_nmi_mask

[Santosh Shukla <santosh.shukla@xxxxxxx>]

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.

Adding API(get_vnmi_vmcb) in order to return the correct vmcb for L1 or
L2.

Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx>
---
v2:
- Added get_vnmi_vmcb API to return vmcb for l1 and l2.
- Use get_vnmi_vmcb to get correct vmcb in func -
  is_vnmi_enabled/_mask_set()
- removed vnmi check from is_vnmi_enabled() func.

 arch/x86/kvm/svm/svm.c | 12 ++++++++++--
 arch/x86/kvm/svm/svm.h | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index baaf35be36e5..3574e804d757 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -198,7 +198,7 @@ module_param(dump_invalid_vmcb, bool, 0644);
 bool intercept_smi = true;
 module_param(intercept_smi, bool, 0444);
 
-static bool vnmi;
+bool vnmi = true;
 module_param(vnmi, bool, 0444);
 
 static bool svm_gp_erratum_intercept = true;
@@ -3503,13 +3503,21 @@ 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))
+		return is_vnmi_mask_set(svm);
+	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))
+		return;
+
 	if (masked) {
 		vcpu->arch.hflags |= HF_NMI_MASK;
 		if (!sev_es_guest(vcpu->kvm))
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 9223ac100ef5..f36e30df6202 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -35,6 +35,7 @@ extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
 extern bool npt_enabled;
 extern int vgif;
 extern bool intercept_smi;
+extern bool vnmi;
 
 /*
  * Clean bits in VMCB.
@@ -509,6 +510,37 @@ static inline bool nested_npt_enabled(struct vcpu_svm *svm)
 	return svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE;
 }
 
+static inline struct vmcb *get_vnmi_vmcb(struct vcpu_svm *svm)
+{
+	if (!vnmi)
+		return NULL;
+
+	if (is_guest_mode(&svm->vcpu))
+		return svm->nested.vmcb02.ptr;
+	else
+		return svm->vmcb01.ptr;
+}
+
+static inline bool is_vnmi_enabled(struct vcpu_svm *svm)
+{
+	struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+	if (vmcb)
+		return !!(vmcb->control.int_ctl & V_NMI_ENABLE);
+	else
+		return false;
+}
+
+static inline bool is_vnmi_mask_set(struct vcpu_svm *svm)
+{
+	struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+	if (vmcb)
+		return !!(vmcb->control.int_ctl & V_NMI_MASK);
+	else
+		return false;
+}
+
 /* svm.c */
 #define MSR_INVALID				0xffffffffU
 
-- 
2.25.1