HV: Install a NMI handler in acrn IDT

This patch installs a NMI handler in acrn IDT to handle
NMIs out of dispatch_exception.

Tracked-On: #3886
Acked-by: Eddie Dong <eddie.dong@intel.com>
Signed-off-by: Kaige Fu <kaige.fu@intel.com>

hypervisor/arch/x86/idt.S

@@ -110,9 +110,9 @@ excp_debug:
 
 .align 8
 excp_nmi:
-
-
-
+	pushq  $0x0			/* pseudo error code */
+	pushq  $0x2
+	jmp    nmi_save_frame
 
 .align 8
 excp_breakpoint:
@@ -330,6 +330,19 @@ excp_rsvd:
 
     iretq
 
+/*
+ * Common entry point for NMI interrupts
+ */
+.align 8
+nmi_save_frame:
+    save_frame
+
+    call   handle_nmi
+
+    restore_frame
+
+    iretq
+
 
 /*
  * Common entry point for defined interrupts.

hypervisor/arch/x86/irq.c

@@ -382,6 +382,14 @@ void dispatch_exception(struct intr_excp_ctx *ctx)
 	cpu_dead();
 }
 
+void handle_nmi(__unused struct intr_excp_ctx *ctx)
+{
+	/*
+	 * Just ignore the NMI here for now.
+	 * TODO: implement specific NMI handling function.
+	 */
+}
+
 static void init_irq_descs(void)
 {
 	uint32_t i;

hypervisor/include/arch/x86/irq.h

@@ -302,6 +302,15 @@ uint32_t irq_to_vector(uint32_t irq);
  */
 void dispatch_interrupt(const struct intr_excp_ctx *ctx);
 
+/**
+ * @brief Handle NMI
+ *
+ * To handle an NMI
+ *
+ * @param ctx Pointer to interrupt exception context
+ */
+void handle_nmi(__unused struct intr_excp_ctx *ctx);
+
 /**
  * @brief Initialize interrupt
  *