[Qemu-devel] [PATCH 5/9] virtio-serial: Handle scatter/gather input from the guest

[Amit Shah <amit.shah@redhat.com>]

Current guests don't send more than one iov but it can change later.
Ensure we handle that case.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Avi Kivity <avi@redhat.com>
---
 hw/virtio-serial-bus.c |   22 +++++++++++++++-------
 1 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index d5887ab..19e8c59 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -338,11 +338,12 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
 
     while (virtqueue_pop(vq, &elem)) {
         VirtIOSerialPort *port;
-        size_t ret;
+        size_t len;
+        unsigned int i;
 
+        len = 0;
         port = find_port_by_vq(vser, vq);
         if (!port) {
-            ret = 0;
             goto next_buf;
         }
 
@@ -352,16 +353,23 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
          * with it. Just ignore the data in that case.
          */
         if (!port->info->have_data) {
-            ret = 0;
             goto next_buf;
         }
 
-        /* The guest always sends only one sg */
-        ret = port->info->have_data(port, elem.out_sg[0].iov_base,
-                                    elem.out_sg[0].iov_len);
+        for (i = 0; i < elem.out_num; i++) {
+            size_t ret;
+
+            ret = port->info->have_data(port, elem.out_sg[0].iov_base,
+                                        elem.out_sg[0].iov_len);
+            if (ret < elem.out_sg[0].iov_len) {
+                /* We couldn't write the entire iov; stop processing now */
+                break;
+            }
+            len += ret;
+        }
 
     next_buf:
-        virtqueue_push(vq, &elem, ret);
+        virtqueue_push(vq, &elem, len);
     }
     virtio_notify(vdev, vq);
 }
-- 
1.6.2.5