xen/events: switch user event channels to lateeoi model

mainline inclusion
from mainline-v5.10
commit c44b849c
category: bugfix
bugzilla: NA
CVE: NA

--------------------------------

Instead of disabling the irq when an event is received and enabling
it again when handled by the user process use the lateeoi model.

This is part of XSA-332.

Cc: stable@vger.kernel.org
Reported-by: NJulien Grall <julien@xen.org>
Signed-off-by: NJuergen Gross <jgross@suse.com>
Tested-by: NStefano Stabellini <sstabellini@kernel.org>
Reviewed-by: NStefano Stabellini <sstabellini@kernel.org>
Reviewed-by: NJan Beulich <jbeulich@suse.com>
Reviewed-by: NWei Liu <wl@xen.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/xen/evtchn.c

@@ -166,7 +166,6 @@ static irqreturn_t evtchn_interrupt(int irq, void *data)
 	     "Interrupt for port %d, but apparently not enabled; per-user %p\n",
 	     evtchn->port, u);
 
-	disable_irq_nosync(irq);
 	evtchn->enabled = false;
 
 	spin_lock(&u->ring_prod_lock);
@@ -292,7 +291,7 @@ static ssize_t evtchn_write(struct file *file, const char __user *buf,
 		evtchn = find_evtchn(u, port);
 		if (evtchn && !evtchn->enabled) {
 			evtchn->enabled = true;
-			enable_irq(irq_from_evtchn(port));
+			xen_irq_lateeoi(irq_from_evtchn(port), 0);
 		}
 	}
 
@@ -392,7 +391,7 @@ static int evtchn_bind_to_user(struct per_user_data *u, int port)
 	if (rc < 0)
 		goto err;
 
-	rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
+	rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
 					       u->name, evtchn);
 	if (rc < 0)
 		goto err;