This patch enables the virtio-net tx queue size to be configurable
between 256 (the default queue size) and 1024 by the user when the
vhost-user backend is used.
Currently, the maximum tx queue size for other backends is 512 due
to the following limitations:
- QEMU backend: the QEMU backend implementation in some cases may
send 1024+1 iovs to writev.
- Vhost_net backend: there are possibilities that the guest sends
a vring_desc of memory which corsses a MemoryRegion thereby
generating more than 1024 iovs after translattion from guest-physical
address in the backend.
Signed-off-by: Wei Wang <wei.w.w...@intel.com>
---
hw/net/virtio-net.c | 45 +++++++++++++++++++++++++++++++++---------
include/hw/virtio/virtio-net.h | 1 +
2 files changed, 37 insertions(+), 9 deletions(-)
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 91eddaf..d13ca60 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -34,8 +34,11 @@
/* previously fixed value */
#define VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE 256
+#define VIRTIO_NET_TX_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
+#define VIRTIO_NET_TX_QUEUE_MIN_SIZE VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE
/*
* Calculate the number of bytes up to and including the given 'field' of
@@ -1508,15 +1511,18 @@ static void virtio_net_add_queue(VirtIONet *n, int
index)
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);
+ virtio_add_queue(vdev, n->net_conf.tx_queue_size,
+ virtio_net_handle_tx_timer);
n->vqs[index].tx_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
virtio_net_tx_timer,
&n->vqs[index]);
} else {
n->vqs[index].tx_vq =
- virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh);
+ virtio_add_queue(vdev, n->net_conf.tx_queue_size,
+ virtio_net_handle_tx_bh);
n->vqs[index].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[index]);
}
@@ -1927,6 +1933,17 @@ static void virtio_net_device_realize(DeviceState *dev,
Error **errp)
return;
}
+ if (n->net_conf.tx_queue_size < VIRTIO_NET_TX_QUEUE_MIN_SIZE ||
+ n->net_conf.tx_queue_size > VIRTQUEUE_MAX_SIZE ||
+ !is_power_of_2(n->net_conf.tx_queue_size)) {
+ error_setg(errp, "Invalid tx_queue_size (= %" PRIu16 "), "
+ "must be a power of 2 between %d and %d",
+ n->net_conf.tx_queue_size, VIRTIO_NET_TX_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 "), "
@@ -1947,17 +1964,11 @@ static void virtio_net_device_realize(DeviceState *dev,
Error **errp)
error_report("Defaulting to \"bh\"");
}
- for (i = 0; i < n->max_queues; i++) {
- virtio_net_add_queue(n, i);
- }
-
- n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
qemu_macaddr_default_if_unset(&n->nic_conf.macaddr);
memcpy(&n->mac[0], &n->nic_conf.macaddr, sizeof(n->mac));
n->status = VIRTIO_NET_S_LINK_UP;
n->announce_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
virtio_net_announce_timer, n);
-
if (n->netclient_type) {
/*
* Happen when virtio_net_set_netclient_name has been called.
@@ -1968,6 +1979,21 @@ static void virtio_net_device_realize(DeviceState *dev,
Error **errp)
n->nic = qemu_new_nic(&net_virtio_info, &n->nic_conf,
object_get_typename(OBJECT(dev)), dev->id, n);
}
+ nc = qemu_get_queue(n->nic);
+
+ /*
+ * Currently, backends other than vhost-user don't support 1024 queue
+ * size.
+ */
+ if (n->net_conf.tx_queue_size == VIRTQUEUE_MAX_SIZE &&
+ nc->peer->info->type != NET_CLIENT_DRIVER_VHOST_USER) {
+ n->net_conf.tx_queue_size = VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE;
+ }
+
+ for (i = 0; i < n->max_queues; i++) {
+ virtio_net_add_queue(n, i);
+ }
+ n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
peer_test_vnet_hdr(n);
if (peer_has_vnet_hdr(n)) {
@@ -1990,7 +2016,6 @@ static void virtio_net_device_realize(DeviceState *dev,
Error **errp)
n->vlans = g_malloc0(MAX_VLAN >> 3);
- nc = qemu_get_queue(n->nic);
nc->rxfilter_notify_enabled = 1;
n->qdev = dev;
@@ -2106,6 +2131,8 @@ static Property virtio_net_properties[] = {
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_UINT16("tx_queue_size", VirtIONet, net_conf.tx_queue_size,
+ VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE),
DEFINE_PROP_UINT16("host_mtu", VirtIONet, net_conf.mtu, 0),
DEFINE_PROP_BOOL("x-mtu-bypass-backend", VirtIONet, mtu_bypass_backend,
true),
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 602b486..b81b6a4 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -36,6 +36,7 @@ typedef struct virtio_net_conf
int32_t txburst;
char *tx;
uint16_t rx_queue_size;
+ uint16_t tx_queue_size;
uint16_t mtu;
} virtio_net_conf;
--
2.7.4
