[PATCH 4.4 56/64] xen/events: switch user event channels to lateeoi model

Greg Kroah-Hartman
2020-11-17T14:06:23Z

From: Juergen Gross <jgross@suse.com>

commit c44b849cee8c3ac587da3b0980e01f77500d158c upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/xen/evtchn.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -173,7 +173,6 @@ static irqreturn_t evtchn_interrupt(int
"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);
@@ -299,7 +298,7 @@ static ssize_t evtchn_write(struct file
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);
}
}

@@ -399,8 +398,8 @@ static int evtchn_bind_to_user(struct pe
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;