[PATCH 2/4] um: virtio: disable VQs during suspend

[Johannes Berg]

From: Johannes Berg <johannes.berg at intel.com>

If the system is suspended, the device shouldn't be able to send
anything to it. Disable virtqueues in suspend to simulate this,
and as we might be only using s2idle (kernel services are still
on), prevent sending anything on them as well.

Signed-off-by: Johannes Berg <johannes.berg at intel.com>
---
 arch/um/drivers/virtio_uml.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index ead9a1aea192..c400a8e64f7c 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -65,6 +65,7 @@ struct virtio_uml_vq_info {
 	vq_callback_t *callback;
 	struct time_travel_event defer;
 #endif
+	bool suspended;
 };
 
 extern unsigned long long physmem_size, highmem;
@@ -722,6 +723,9 @@ static bool vu_notify(struct virtqueue *vq)
 	const uint64_t n = 1;
 	int rc;
 
+	if (info->suspended)
+		return true;
+
 	time_travel_propagate_time();
 
 	if (info->kick_fd < 0) {
@@ -1284,6 +1288,36 @@ static const struct of_device_id virtio_uml_match[] = {
 };
 MODULE_DEVICE_TABLE(of, virtio_uml_match);
 
+static int virtio_uml_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct virtio_uml_device *vu_dev = platform_get_drvdata(pdev);
+	struct virtqueue *vq;
+
+	virtio_device_for_each_vq((&vu_dev->vdev), vq) {
+		struct virtio_uml_vq_info *info = vq->priv;
+
+		info->suspended = true;
+		vhost_user_set_vring_enable(vu_dev, vq->index, false);
+	}
+
+	return 0;
+}
+
+static int virtio_uml_resume(struct platform_device *pdev)
+{
+	struct virtio_uml_device *vu_dev = platform_get_drvdata(pdev);
+	struct virtqueue *vq;
+
+	virtio_device_for_each_vq((&vu_dev->vdev), vq) {
+		struct virtio_uml_vq_info *info = vq->priv;
+
+		info->suspended = false;
+		vhost_user_set_vring_enable(vu_dev, vq->index, true);
+	}
+
+	return 0;
+}
+
 static struct platform_driver virtio_uml_driver = {
 	.probe = virtio_uml_probe,
 	.remove = virtio_uml_remove,
@@ -1291,6 +1325,8 @@ static struct platform_driver virtio_uml_driver = {
 		.name = "virtio-uml",
 		.of_match_table = virtio_uml_match,
 	},
+	.suspend = virtio_uml_suspend,
+	.resume = virtio_uml_resume,
 };
 
 static int __init virtio_uml_init(void)
-- 
2.26.2