KVM: SVM: introduce nested_run_pending

We want to inject vmexits immediately from svm_check_nested_events,
so that the interrupt/NMI window requests happen in inject_pending_event
right after it returns.

This however has the same issue as in vmx_check_nested_events, so
introduce a nested_run_pending flag with the exact same purpose
of delaying vmexit injection after the vmentry.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/nested.c

@@ -414,6 +414,7 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
 
 	copy_vmcb_control_area(hsave, vmcb);
 
+	svm->nested.nested_run_pending = 1;
 	enter_svm_guest_mode(svm, vmcb_gpa, nested_vmcb, &map);
 
 	if (!nested_svm_vmrun_msrpm(svm)) {
@@ -815,7 +816,8 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	bool block_nested_events =
-		kvm_event_needs_reinjection(vcpu) || svm->nested.exit_required;
+		kvm_event_needs_reinjection(vcpu) || svm->nested.exit_required ||
+		svm->nested.nested_run_pending;
 
 	if (kvm_cpu_has_interrupt(vcpu) && nested_exit_on_intr(svm)) {
 		if (block_nested_events)

arch/x86/kvm/svm/svm.c

@@ -3429,6 +3429,7 @@ static enum exit_fastpath_completion svm_vcpu_run(struct kvm_vcpu *vcpu)
 	sync_cr8_to_lapic(vcpu);
 
 	svm->next_rip = 0;
+	svm->nested.nested_run_pending = 0;
 
 	svm->vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
 

arch/x86/kvm/svm/svm.h

@@ -97,6 +97,10 @@ struct nested_state {
 	/* A VMEXIT is required but not yet emulated */
 	bool exit_required;
 
+	/* A VMRUN has started but has not yet been performed, so
+	 * we cannot inject a nested vmexit yet.  */
+	bool nested_run_pending;
+
 	/* cache for intercepts of the guest */
 	u32 intercept_cr;
 	u32 intercept_dr;