#include "vhost.h"
-static int experimental_zcopytx;
+static int experimental_zcopytx = 1;
module_param(experimental_zcopytx, int, 0444);
-MODULE_PARM_DESC(experimental_zcopytx, "Enable Experimental Zero Copy TX");
+MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
+ " 1 -Enable; 0 - Disable");
/* Max number of bytes transferred before requeueing the job.
* Using this limit prevents one virtqueue from starving others. */
#define VHOST_MAX_PEND 128
#define VHOST_GOODCOPY_LEN 256
+/*
+ * For transmit, used buffer len is unused; we override it to track buffer
+ * status internally; used for zerocopy tx only.
+ */
+/* Lower device DMA failed */
+#define VHOST_DMA_FAILED_LEN 3
+/* Lower device DMA done */
+#define VHOST_DMA_DONE_LEN 2
+/* Lower device DMA in progress */
+#define VHOST_DMA_IN_PROGRESS 1
+/* Buffer unused */
+#define VHOST_DMA_CLEAR_LEN 0
+
+#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
+
enum {
VHOST_NET_VQ_RX = 0,
VHOST_NET_VQ_TX = 1,
* We only do this when socket buffer fills up.
* Protected by tx vq lock. */
enum vhost_net_poll_state tx_poll_state;
+ /* Number of TX recently submitted.
+ * Protected by tx vq lock. */
+ unsigned tx_packets;
+ /* Number of times zerocopy TX recently failed.
+ * Protected by tx vq lock. */
+ unsigned tx_zcopy_err;
+ /* Flush in progress. Protected by tx vq lock. */
+ bool tx_flush;
};
+static void vhost_net_tx_packet(struct vhost_net *net)
+{
+ ++net->tx_packets;
+ if (net->tx_packets < 1024)
+ return;
+ net->tx_packets = 0;
+ net->tx_zcopy_err = 0;
+}
+
+static void vhost_net_tx_err(struct vhost_net *net)
+{
+ ++net->tx_zcopy_err;
+}
+
+static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
+{
+ /* TX flush waits for outstanding DMAs to be done.
+ * Don't start new DMAs.
+ */
+ return !net->tx_flush &&
+ net->tx_packets / 64 >= net->tx_zcopy_err;
+}
+
static bool vhost_sock_zcopy(struct socket *sock)
{
return unlikely(experimental_zcopytx) &&
}
/* Caller must have TX VQ lock */
-static void tx_poll_start(struct vhost_net *net, struct socket *sock)
+static int tx_poll_start(struct vhost_net *net, struct socket *sock)
{
+ int ret;
+
if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
- return;
- vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
- net->tx_poll_state = VHOST_NET_POLL_STARTED;
+ return 0;
+ ret = vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
+ if (!ret)
+ net->tx_poll_state = VHOST_NET_POLL_STARTED;
+ return ret;
+}
+
+/* In case of DMA done not in order in lower device driver for some reason.
+ * upend_idx is used to track end of used idx, done_idx is used to track head
+ * of used idx. Once lower device DMA done contiguously, we will signal KVM
+ * guest used idx.
+ */
+static int vhost_zerocopy_signal_used(struct vhost_net *net,
+ struct vhost_virtqueue *vq)
+{
+ int i;
+ int j = 0;
+
+ for (i = vq->done_idx; i != vq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
+ if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
+ vhost_net_tx_err(net);
+ if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
+ vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
+ vhost_add_used_and_signal(vq->dev, vq,
+ vq->heads[i].id, 0);
+ ++j;
+ } else
+ break;
+ }
+ if (j)
+ vq->done_idx = i;
+ return j;
+}
+
+static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
+{
+ struct vhost_ubuf_ref *ubufs = ubuf->ctx;
+ struct vhost_virtqueue *vq = ubufs->vq;
+ int cnt = atomic_read(&ubufs->kref.refcount);
+
+ /*
+ * Trigger polling thread if guest stopped submitting new buffers:
+ * in this case, the refcount after decrement will eventually reach 1
+ * so here it is 2.
+ * We also trigger polling periodically after each 16 packets
+ * (the value 16 here is more or less arbitrary, it's tuned to trigger
+ * less than 10% of times).
+ */
+ if (cnt <= 2 || !(cnt % 16))
+ vhost_poll_queue(&vq->poll);
+ /* set len to mark this desc buffers done DMA */
+ vq->heads[ubuf->desc].len = success ?
+ VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
+ vhost_ubuf_put(ubufs);
}
/* Expects to be always run from workqueue - which acts as
size_t hdr_size;
struct socket *sock;
struct vhost_ubuf_ref *uninitialized_var(ubufs);
- bool zcopy;
+ bool zcopy, zcopy_used;
/* TODO: check that we are running from vhost_worker? */
sock = rcu_dereference_check(vq->private_data, 1);
for (;;) {
/* Release DMAs done buffers first */
if (zcopy)
- vhost_zerocopy_signal_used(vq);
+ vhost_zerocopy_signal_used(net, vq);
head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
ARRAY_SIZE(vq->iov),
iov_length(vq->hdr, s), hdr_size);
break;
}
+ zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
+ vq->upend_idx != vq->done_idx);
+
/* use msg_control to pass vhost zerocopy ubuf info to skb */
- if (zcopy) {
+ if (zcopy_used) {
vq->heads[vq->upend_idx].id = head;
- if (len < VHOST_GOODCOPY_LEN) {
+ if (!vhost_net_tx_select_zcopy(net) ||
+ len < VHOST_GOODCOPY_LEN) {
/* copy don't need to wait for DMA done */
vq->heads[vq->upend_idx].len =
VHOST_DMA_DONE_LEN;
} else {
struct ubuf_info *ubuf = &vq->ubuf_info[head];
- vq->heads[vq->upend_idx].len = len;
+ vq->heads[vq->upend_idx].len =
+ VHOST_DMA_IN_PROGRESS;
ubuf->callback = vhost_zerocopy_callback;
ubuf->ctx = vq->ubufs;
ubuf->desc = vq->upend_idx;
/* TODO: Check specific error and bomb out unless ENOBUFS? */
err = sock->ops->sendmsg(NULL, sock, &msg, len);
if (unlikely(err < 0)) {
- if (zcopy) {
+ if (zcopy_used) {
if (ubufs)
vhost_ubuf_put(ubufs);
vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
if (err != len)
pr_debug("Truncated TX packet: "
" len %d != %zd\n", err, len);
- if (!zcopy)
+ if (!zcopy_used)
vhost_add_used_and_signal(&net->dev, vq, head, 0);
else
- vhost_zerocopy_signal_used(vq);
+ vhost_zerocopy_signal_used(net, vq);
total_len += len;
+ vhost_net_tx_packet(net);
if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
vhost_poll_queue(&vq->poll);
break;
vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
}
-static void vhost_net_enable_vq(struct vhost_net *n,
+static int vhost_net_enable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct socket *sock;
+ int ret;
sock = rcu_dereference_protected(vq->private_data,
lockdep_is_held(&vq->mutex));
if (!sock)
- return;
+ return 0;
if (vq == n->vqs + VHOST_NET_VQ_TX) {
n->tx_poll_state = VHOST_NET_POLL_STOPPED;
- tx_poll_start(n, sock);
+ ret = tx_poll_start(n, sock);
} else
- vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
+ ret = vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
+
+ return ret;
}
static struct socket *vhost_net_stop_vq(struct vhost_net *n,
{
vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
+ if (n->dev.vqs[VHOST_NET_VQ_TX].ubufs) {
+ mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+ n->tx_flush = true;
+ mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+ /* Wait for all lower device DMAs done. */
+ vhost_ubuf_put_and_wait(n->dev.vqs[VHOST_NET_VQ_TX].ubufs);
+ mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+ n->tx_flush = false;
+ kref_init(&n->dev.vqs[VHOST_NET_VQ_TX].ubufs->kref);
+ mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
+ }
}
static int vhost_net_release(struct inode *inode, struct file *f)
vhost_net_stop(n, &tx_sock, &rx_sock);
vhost_net_flush(n);
+ vhost_dev_stop(&n->dev);
vhost_dev_cleanup(&n->dev, false);
if (tx_sock)
fput(tx_sock->file);
r = PTR_ERR(ubufs);
goto err_ubufs;
}
- oldubufs = vq->ubufs;
- vq->ubufs = ubufs;
+
vhost_net_disable_vq(n, vq);
rcu_assign_pointer(vq->private_data, sock);
- vhost_net_enable_vq(n, vq);
-
r = vhost_init_used(vq);
if (r)
- goto err_vq;
+ goto err_used;
+ r = vhost_net_enable_vq(n, vq);
+ if (r)
+ goto err_used;
+
+ oldubufs = vq->ubufs;
+ vq->ubufs = ubufs;
+
+ n->tx_packets = 0;
+ n->tx_zcopy_err = 0;
+ n->tx_flush = false;
}
mutex_unlock(&vq->mutex);
if (oldubufs) {
vhost_ubuf_put_and_wait(oldubufs);
mutex_lock(&vq->mutex);
- vhost_zerocopy_signal_used(vq);
+ vhost_zerocopy_signal_used(n, vq);
mutex_unlock(&vq->mutex);
}
mutex_unlock(&n->dev.mutex);
return 0;
+err_used:
+ rcu_assign_pointer(vq->private_data, oldsock);
+ vhost_net_enable_vq(n, vq);
+ if (ubufs)
+ vhost_ubuf_put_and_wait(ubufs);
err_ubufs:
fput(sock->file);
err_vq:
return vhost_net_reset_owner(n);
default:
mutex_lock(&n->dev.mutex);
- r = vhost_dev_ioctl(&n->dev, ioctl, arg);
- vhost_net_flush(n);
+ r = vhost_dev_ioctl(&n->dev, ioctl, argp);
+ if (r == -ENOIOCTLCMD)
+ r = vhost_vring_ioctl(&n->dev, ioctl, argp);
+ else
+ vhost_net_flush(n);
mutex_unlock(&n->dev.mutex);
return r;
}
git.openpandora.org / pandora-kernel.git / blobdiff