x86/hyperv: Register the handler of redirected proxy interrupts

Implement the hv_{setup, remove}__redirected_proxy_intr_handler() function.
Store a pointer to the handler that the Hyper-V VTL driver provides. It
will be needed when dispatching hardware interrupt vectors that have been
mapped to proxy interrupts.

Signed-off-by: Ricardo Neri <[email protected]>
---
Changes since v1:
 * None

Author: ricardon

arch/x86/kernel/cpu/mshyperv.c

@@ -115,6 +115,9 @@ static void (*vmbus_handler)(void);
 static void (*hv_stimer0_handler)(void);
 static void (*hv_kexec_handler)(void);
 static void (*hv_crash_handler)(struct pt_regs *regs);
+#ifdef CONFIG_HYPERV_VTL_MODE
+static void (*hv_redirected_proxy_intr_handler)(u32 vector);
+#endif
 
 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
 {
@@ -214,6 +217,23 @@ void hv_remove_crash_handler(void)
 	hv_crash_handler = NULL;
 }
 
+#ifdef CONFIG_HYPERV_VTL_MODE
+void hv_setup_redirected_proxy_intr_handler(void (*handler)(u32 vector))
+{
+	hv_redirected_proxy_intr_handler = handler;
+}
+
+void hv_remove_redirected_proxy_intr_handler(void)
+{
+	/*
+	 * The interrupt gate is still allocated. Interrupts will
+	 * continue to be acked with out a handler they cannot be
+	 * proper processed.
+	 */
+	hv_redirected_proxy_intr_handler = NULL;
+}
+#endif
+
 #ifdef CONFIG_KEXEC_CORE
 static void hv_machine_shutdown(void)
 {