VMX: issue an NMI rather than just calling the NMI handler

when the VMEXIT code indicates that an NMI has been raised.
Otherwise we might hit a real NMI while in the handler.

Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>

xen/arch/x86/hvm/vmx/vmx.c

@@ -945,8 +945,6 @@ static void vmx_enable_rdtsc_exiting(struct vcpu *v)
     vmx_vmcs_exit(v);
  }
 
-void do_nmi(struct cpu_user_regs *);
-
 static void vmx_init_hypercall_page(struct domain *d, void *hypercall_page)
 {
     char *p;
@@ -2470,7 +2468,7 @@ asmlinkage void vmx_vmexit_handler(struct cpu_user_regs *regs)
                  (X86_EVENTTYPE_NMI << 8) )
                 goto exit_and_crash;
             HVMTRACE_0D(NMI);
-            do_nmi(regs); /* Real NMI, vector 2: normal processing. */
+            self_nmi(); /* Real NMI, vector 2: normal processing. */
             break;
         case TRAP_machine_check:
             HVMTRACE_0D(MCE);

xen/arch/x86/nmi.c

@@ -441,18 +441,21 @@ void nmi_watchdog_tick(struct cpu_user_regs * regs)
  * 8-3 and 8-4 in IA32 Reference Manual Volume 3. We send the IPI to
  * our own APIC ID explicitly which is valid.
  */
-static void do_nmi_trigger(unsigned char key)
+void self_nmi(void) 
 {
     u32 id = get_apic_id();
-
-    printk("Triggering NMI on APIC ID %x\n", id);
-
     local_irq_disable();
     apic_wait_icr_idle();
     apic_icr_write(APIC_DM_NMI | APIC_DEST_PHYSICAL, id);
     local_irq_enable();
 }
 
+static void do_nmi_trigger(unsigned char key)
+{
+    printk("Triggering NMI on APIC ID %x\n", get_apic_id());
+    self_nmi();
+}
+
 static struct keyhandler nmi_trigger_keyhandler = {
     .u.fn = do_nmi_trigger,
     .desc = "trigger an NMI"

xen/include/asm-x86/apic.h

@@ -196,6 +196,7 @@ extern void setup_secondary_APIC_clock (void);
 extern void setup_apic_nmi_watchdog (void);
 extern int reserve_lapic_nmi(void);
 extern void release_lapic_nmi(void);
+extern void self_nmi(void);
 extern void disable_timer_nmi_watchdog(void);
 extern void enable_timer_nmi_watchdog(void);
 extern void nmi_watchdog_tick (struct cpu_user_regs *regs);