[PATCHv4 5/8] KVM: SVM: Add VNMI support in inject_nmi

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

Inject the NMI by setting V_NMI in the VMCB interrupt control. processor
will clear V_NMI to acknowledge processing has started and will keep the
V_NMI_MASK set until the processor is done with processing the NMI event.

Also, handle the nmi_l1_to_l2 case such that when it is true then
NMI to be injected originally comes from L1's VMCB12 EVENTINJ field.
So adding a check for that case.

Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
---
v4:
- Added `nmi_l1_to_l2` check, discussion thread
https://lore.kernel.org/all/bf9e8a9c-5172-b61a-be6e-87a919442fbd@maciej.szmigiero.name/

v3:
- Removed WARN_ON check.

v2:
- Added WARN_ON check for vnmi pending.
- use `get_vnmi_vmcb` to get correct vmcb so to inject vnmi.
 arch/x86/kvm/svm/svm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 810b93774a95..4aa7606a9aa2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3479,7 +3479,14 @@ static void pre_svm_run(struct kvm_vcpu *vcpu)
 static void svm_inject_nmi(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
+	struct vmcb *vmcb = NULL;
 
+	if (is_vnmi_enabled(svm) && !svm->nmi_l1_to_l2) {
+		vmcb = get_vnmi_vmcb(svm);
+		vmcb->control.int_ctl |= V_NMI_PENDING;
+		++vcpu->stat.nmi_injections;
+		return;
+	}
 	svm->vmcb->control.event_inj = SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_NMI;
 
 	if (svm->nmi_l1_to_l2)
-- 
2.25.1