kvm: Enable user space NMI injection for kvm guest

Make use of the new KVM_NMI IOCTL to send NMIs into the KVM guest if the
user space raised them. (example: qemu monitor's "nmi" command)
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

configure

@@ -1671,6 +1671,9 @@ if test "$kvm" != "no" ; then
 #if !defined(KVM_CAP_DESTROY_MEMORY_REGION_WORKS)
 #error Missing KVM capability KVM_CAP_DESTROY_MEMORY_REGION_WORKS
 #endif
+#if !defined(KVM_CAP_USER_NMI)
+#error Missing KVM capability KVM_CAP_USER_NMI
+#endif
 int main(void) { return 0; }
 EOF
   if test "$kerneldir" != "" ; then

target-i386/kvm.c

@@ -1417,6 +1417,13 @@ int kvm_arch_get_registers(CPUState *env)
 
 int kvm_arch_pre_run(CPUState *env, struct kvm_run *run)
 {
+    /* Inject NMI */
+    if (env->interrupt_request & CPU_INTERRUPT_NMI) {
+        env->interrupt_request &= ~CPU_INTERRUPT_NMI;
+        DPRINTF("injected NMI\n");
+        kvm_vcpu_ioctl(env, KVM_NMI);
+    }
+
     /* Try to inject an interrupt if the guest can accept it */
     if (run->ready_for_interrupt_injection &&
         (env->interrupt_request & CPU_INTERRUPT_HARD) &&