vhost-scsi: Fix vhost_scsi_send_status()

Although the support of VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 was
signaled by the commit 664ed90 ("vhost/scsi: Set
VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 feature bits"),
vhost_scsi_send_bad_target() still assumes the response in a single
descriptor.

Similar issue in vhost_scsi_send_bad_target() has been fixed in previous
commit. In addition, similar issue for vhost_scsi_complete_cmd_work() has
been fixed by the commit 6dd88fd ("vhost-scsi: unbreak any layout for
response").

Fixes: 3ca5166 ("vhost-scsi: Add better resource allocation failure handling")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-4-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/scsi.c

@@ -999,18 +999,22 @@ static void vhost_scsi_target_queue_cmd(struct vhost_scsi_nexus *nexus,
 
 static void
 vhost_scsi_send_status(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
-		       int head, unsigned int out, u8 status)
+		       struct vhost_scsi_ctx *vc, u8 status)
 {
-	struct virtio_scsi_cmd_resp __user *resp;
 	struct virtio_scsi_cmd_resp rsp;
+	struct iov_iter iov_iter;
 	int ret;
 
 	memset(&rsp, 0, sizeof(rsp));
 	rsp.status = status;
-	resp = vq->iov[out].iov_base;
-	ret = __copy_to_user(resp, &rsp, sizeof(rsp));
-	if (!ret)
-		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+
+	iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[vc->out], vc->in,
+		      sizeof(rsp));
+
+	ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
+
+	if (likely(ret == sizeof(rsp)))
+		vhost_add_used_and_signal(&vs->dev, vq, vc->head, 0);
 	else
 		pr_err("Faulted on virtio_scsi_cmd_resp\n");
 }
@@ -1420,7 +1424,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 		else if (ret == -EIO)
 			vhost_scsi_send_bad_target(vs, vq, &vc, TYPE_IO_CMD);
 		else if (ret == -ENOMEM)
-			vhost_scsi_send_status(vs, vq, vc.head, vc.out,
+			vhost_scsi_send_status(vs, vq, &vc,
 					       SAM_STAT_TASK_SET_FULL);
 	} while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
 out: