From 7d3cfbeefe16f8909c2924e98066bc315aad8656 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Mon, 7 Sep 2020 15:47:29 +0200
Subject: [PATCH 09/12] xen/events: switch user event channels to lateeoi
 model

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: Julien Grall <julien@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
---
 drivers/xen/evtchn.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index 6e0b1dd5573c..5dc016d68f83 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -167,7 +167,6 @@ static irqreturn_t evtchn_interrupt(int irq, void *data)
 	     "Interrupt for port %u, but apparently not enabled; per-user %p\n",
 	     evtchn->port, u);
 
-	disable_irq_nosync(irq);
 	evtchn->enabled = false;
 
 	spin_lock(&u->ring_prod_lock);
@@ -293,7 +292,7 @@ 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);
 		}
 	}
 
@@ -393,8 +392,8 @@ static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
 	if (rc < 0)
 		goto err;
 
-	rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
-				       u->name, evtchn);
+	rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
+					       u->name, evtchn);
 	if (rc < 0)
 		goto err;
 
-- 
2.26.2

