KVM: SVM: do not generate "external interrupt exit" if other exit is pending

Nested SVM checks for external interrupt after injecting nested exception.
In case there is external interrupt pending the code generates "external
interrupt exit" and overwrites previous exit info. If previously injected
exception already generated exit it will be lost.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Acked-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/svm.c

@@ -1707,6 +1707,14 @@ static inline bool nested_svm_intr(struct vcpu_svm *svm)
 	if (!(svm->vcpu.arch.hflags & HF_HIF_MASK))
 		return false;
 
+	/*
+	 * if vmexit was already requested (by intercepted exception
+	 * for instance) do not overwrite it with "external interrupt"
+	 * vmexit.
+	 */
+	if (svm->nested.exit_required)
+		return false;
+
 	svm->vmcb->control.exit_code   = SVM_EXIT_INTR;
 	svm->vmcb->control.exit_info_1 = 0;
 	svm->vmcb->control.exit_info_2 = 0;