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-rw-r--r--hw/net/virtio-net.c26
-rw-r--r--include/hw/virtio/virtio-net.h1
2 files changed, 26 insertions, 1 deletions
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 01f1351554..6b8ae2c1fa 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -31,6 +31,11 @@
 #define MAC_TABLE_ENTRIES    64
 #define MAX_VLAN    (1 << 12)   /* Per 802.1Q definition */
 
+/* previously fixed value */
+#define VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE 256
+/* for now, only allow larger queues; with virtio-1, guest can downsize */
+#define VIRTIO_NET_RX_QUEUE_MIN_SIZE VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE
+
 /*
  * Calculate the number of bytes up to and including the given 'field' of
  * 'container'.
@@ -1412,7 +1417,8 @@ static void virtio_net_add_queue(VirtIONet *n, int index)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
 
-    n->vqs[index].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
+    n->vqs[index].rx_vq = virtio_add_queue(vdev, n->net_conf.rx_queue_size,
+                                           virtio_net_handle_rx);
     if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) {
         n->vqs[index].tx_vq =
             virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer);
@@ -1720,6 +1726,22 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
     virtio_net_set_config_size(n, n->host_features);
     virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
 
+    /*
+     * We set a lower limit on RX queue size to what it always was.
+     * Guests that want a smaller ring can always resize it without
+     * help from us (using virtio 1 and up).
+     */
+    if (n->net_conf.rx_queue_size < VIRTIO_NET_RX_QUEUE_MIN_SIZE ||
+        n->net_conf.rx_queue_size > VIRTQUEUE_MAX_SIZE ||
+        (n->net_conf.rx_queue_size & (n->net_conf.rx_queue_size - 1))) {
+        error_setg(errp, "Invalid rx_queue_size (= %" PRIu16 "), "
+                   "must be a power of 2 between %d and %d.",
+                   n->net_conf.rx_queue_size, VIRTIO_NET_RX_QUEUE_MIN_SIZE,
+                   VIRTQUEUE_MAX_SIZE);
+        virtio_cleanup(vdev);
+        return;
+    }
+
     n->max_queues = MAX(n->nic_conf.peers.queues, 1);
     if (n->max_queues * 2 + 1 > VIRTIO_QUEUE_MAX) {
         error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
@@ -1880,6 +1902,8 @@ static Property virtio_net_properties[] = {
                        TX_TIMER_INTERVAL),
     DEFINE_PROP_INT32("x-txburst", VirtIONet, net_conf.txburst, TX_BURST),
     DEFINE_PROP_STRING("tx", VirtIONet, net_conf.tx),
+    DEFINE_PROP_UINT16("rx_queue_size", VirtIONet, net_conf.rx_queue_size,
+                       VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 91ed97cfcd..0ced975c57 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -35,6 +35,7 @@ typedef struct virtio_net_conf
     uint32_t txtimer;
     int32_t txburst;
     char *tx;
+    uint16_t rx_queue_size;
 } virtio_net_conf;
 
 /* Maximum packet size we can receive from tap device: header + 64k */