xen/events: only register debug interrupt for 2-level events

xen_debug_interrupt() is specific to 2-level event handling. So don't
register it with fifo event handling being active.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Link: https://lore.kernel.org/r/20201022094907.28560-4-jgross@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Author: jgross1

arch/x86/xen/smp.c

@@ -88,14 +88,17 @@ int xen_smp_intr_init(unsigned int cpu)
 	per_cpu(xen_callfunc_irq, cpu).irq = rc;
 	per_cpu(xen_callfunc_irq, cpu).name = callfunc_name;
 
-	debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
-	rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
-				     IRQF_PERCPU | IRQF_NOBALANCING,
-				     debug_name, NULL);
-	if (rc < 0)
-		goto fail;
-	per_cpu(xen_debug_irq, cpu).irq = rc;
-	per_cpu(xen_debug_irq, cpu).name = debug_name;
+	if (!xen_fifo_events) {
+		debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
+		rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu,
+					     xen_debug_interrupt,
+					     IRQF_PERCPU | IRQF_NOBALANCING,
+					     debug_name, NULL);
+		if (rc < 0)
+			goto fail;
+		per_cpu(xen_debug_irq, cpu).irq = rc;
+		per_cpu(xen_debug_irq, cpu).name = debug_name;
+	}
 
 	callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
 	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,

arch/x86/xen/xen-ops.h

@@ -29,6 +29,8 @@ extern struct start_info *xen_start_info;
 extern struct shared_info xen_dummy_shared_info;
 extern struct shared_info *HYPERVISOR_shared_info;
 
+extern bool xen_fifo_events;
+
 void xen_setup_mfn_list_list(void);
 void xen_build_mfn_list_list(void);
 void xen_setup_machphys_mapping(void);

drivers/xen/events/events_base.c

@@ -2050,8 +2050,8 @@ void xen_setup_callback_vector(void) {}
 static inline void xen_alloc_callback_vector(void) {}
 #endif
 
-static bool fifo_events = true;
-module_param(fifo_events, bool, 0);
+bool xen_fifo_events = true;
+module_param_named(fifo_events, xen_fifo_events, bool, 0);
 
 static int xen_evtchn_cpu_prepare(unsigned int cpu)
 {
@@ -2080,10 +2080,12 @@ void __init xen_init_IRQ(void)
 	int ret = -EINVAL;
 	evtchn_port_t evtchn;
 
-	if (fifo_events)
+	if (xen_fifo_events)
 		ret = xen_evtchn_fifo_init();
-	if (ret < 0)
+	if (ret < 0) {
 		xen_evtchn_2l_init();
+		xen_fifo_events = false;
+	}
 
 	xen_cpu_init_eoi(smp_processor_id());