xen: mask all event channels on init

Mask all event channels during initialization. This is done so that we
don't receive spurious interrupts while dynamically registering new
event channels. There's a small window during registration where an
event channel can fire before we have attached a handler to it.

Sponsored by: Citrix Systems R&D

x86/xen/xen_intr.c:
 - Mask all event channels on init.

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/x86/xen/xen_intr.c b/sys/x86/xen/xen_intr.c
index b02917c..a3f7f41 100644
--- a/sys/x86/xen/xen_intr.c
+++ b/sys/x86/xen/xen_intr.c
@@ -584,6 +584,7 @@ xen_intr_handle_upcall(struct trapframe *trap_frame)
 static int
 xen_intr_init(void *dummy __unused)
 {
+	shared_info_t *s = HYPERVISOR_shared_info;
 	struct xen_intr_pcpu_data *pcpu;
 	struct physdev_pirq_eoi_gmfn eoi_gmfn;
 	int i, rc;
@@ -607,6 +608,9 @@ xen_intr_init(void *dummy __unused)
 		xen_intr_intrcnt_add(i);
 	}
 
+	for (i = 0; i < nitems(s->evtchn_mask); i++)
+		atomic_store_rel_long(&s->evtchn_mask[i], ~0);
+
 	/* Try to register PIRQ EOI map */
 	xen_intr_pirq_eoi_map = malloc(PAGE_SIZE, M_XENINTR, M_WAITOK | M_ZERO);
 	eoi_gmfn.gmfn = atop(vtophys(xen_intr_pirq_eoi_map));