[PATCH 5.4.y] xen/events: Cleanup find_virq() return codes

[Sasha Levin <sashal@kernel.org>]

From: Jason Andryuk <jason.andryuk@amd.com>

[ Upstream commit 08df2d7dd4ab2db8a172d824cda7872d5eca460a ]

rc is overwritten by the evtchn_status hypercall in each iteration, so
the return value will be whatever the last iteration is.  This could
incorrectly return success even if the event channel was not found.
Change to an explicit -ENOENT for an un-found virq and return 0 on a
successful match.

Fixes: 62cc5fc7b2e0 ("xen/pv-on-hvm kexec: rebind virqs to existing eventchannel ports")
Cc: stable@vger.kernel.org
Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20250828003604.8949-2-jason.andryuk@amd.com>
[ converted evtchn pointer output parameter to direct port return value ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/xen/events/events_base.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index f8554d9a9f28e..fd16b995425dc 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1210,10 +1210,12 @@ EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq_lateeoi);
 static int find_virq(unsigned int virq, unsigned int cpu)
 {
 	struct evtchn_status status;
-	int port, rc = -ENOENT;
+	int port;
 
 	memset(&status, 0, sizeof(status));
 	for (port = 0; port < xen_evtchn_max_channels(); port++) {
+		int rc;
+
 		status.dom = DOMID_SELF;
 		status.port = port;
 		rc = HYPERVISOR_event_channel_op(EVTCHNOP_status, &status);
@@ -1221,12 +1223,10 @@ static int find_virq(unsigned int virq, unsigned int cpu)
 			continue;
 		if (status.status != EVTCHNSTAT_virq)
 			continue;
-		if (status.u.virq == virq && status.vcpu == xen_vcpu_nr(cpu)) {
-			rc = port;
-			break;
-		}
+		if (status.u.virq == virq && status.vcpu == xen_vcpu_nr(cpu))
+			return port;
 	}
-	return rc;
+	return -ENOENT;
 }
 
 /**
-- 
2.51.0