[PATCH RFC v8 06/11] vhost/net: convert to new API: heads->bufs

From: Michael S. Tsirkin
Date: Thu Jun 11 2020 - 07:34:45 EST

Convert vhost net to use the new format-agnostic API.
In particular, don't poke at vq internals such as the
heads array.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
drivers/vhost/net.c | 154 +++++++++++++++++++++++---------------------
1 file changed, 82 insertions(+), 72 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index ff594eec8ae3..830fe84912a5 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -59,13 +59,13 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
* status internally; used for zerocopy tx only.
*/
/* Lower device DMA failed */
-#define VHOST_DMA_FAILED_LEN ((__force __virtio32)3)
+#define VHOST_DMA_FAILED_LEN (3)
/* Lower device DMA done */
-#define VHOST_DMA_DONE_LEN ((__force __virtio32)2)
+#define VHOST_DMA_DONE_LEN (2)
/* Lower device DMA in progress */
-#define VHOST_DMA_IN_PROGRESS ((__force __virtio32)1)
+#define VHOST_DMA_IN_PROGRESS (1)
/* Buffer unused */
-#define VHOST_DMA_CLEAR_LEN ((__force __virtio32)0)
+#define VHOST_DMA_CLEAR_LEN (0)

#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)

@@ -112,9 +112,12 @@ struct vhost_net_virtqueue {
/* last used idx for outstanding DMA zerocopy buffers */
int upend_idx;
/* For TX, first used idx for DMA done zerocopy buffers
- * For RX, number of batched heads
+ * For RX, number of batched bufs
*/
int done_idx;
+ /* Outstanding user bufs. UIO_MAXIOV in length. */
+ /* TODO: we can make this smaller for sure. */
+ struct vhost_buf *bufs;
/* Number of XDP frames batched */
int batched_xdp;
/* an array of userspace buffers info */
@@ -271,6 +274,8 @@ static void vhost_net_clear_ubuf_info(struct vhost_net *n)
int i;

for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+ kfree(n->vqs[i].bufs);
+ n->vqs[i].bufs = NULL;
kfree(n->vqs[i].ubuf_info);
n->vqs[i].ubuf_info = NULL;
}
@@ -282,6 +287,12 @@ static int vhost_net_set_ubuf_info(struct vhost_net *n)
int i;

for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+ n->vqs[i].bufs = kmalloc_array(UIO_MAXIOV,
+ sizeof(*n->vqs[i].bufs),
+ GFP_KERNEL);
+ if (!n->vqs[i].bufs)
+ goto err;
+
zcopy = vhost_net_zcopy_mask & (0x1 << i);
if (!zcopy)
continue;
@@ -364,18 +375,18 @@ static void vhost_zerocopy_signal_used(struct vhost_net *net,
int j = 0;

for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
- if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
+ if (nvq->bufs[i].in_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;
+ if (VHOST_DMA_IS_DONE(nvq->bufs[i].in_len)) {
+ nvq->bufs[i].in_len = VHOST_DMA_CLEAR_LEN;
++j;
} else
break;
}
while (j) {
add = min(UIO_MAXIOV - nvq->done_idx, j);
- vhost_add_used_and_signal_n(vq->dev, vq,
- &vq->heads[nvq->done_idx], add);
+ vhost_put_used_n_bufs(vq, &nvq->bufs[nvq->done_idx], add);
+ vhost_signal(vq->dev, vq);
nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
j -= add;
}
@@ -390,7 +401,7 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
rcu_read_lock_bh();

/* set len to mark this desc buffers done DMA */
- nvq->vq.heads[ubuf->desc].in_len = success ?
+ nvq->bufs[ubuf->desc].in_len = success ?
VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
cnt = vhost_net_ubuf_put(ubufs);

@@ -452,7 +463,8 @@ static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
if (!nvq->done_idx)
return;

- vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
+ vhost_put_used_n_bufs(vq, nvq->bufs, nvq->done_idx);
+ vhost_signal(dev, vq);
nvq->done_idx = 0;
}

@@ -558,6 +570,7 @@ static void vhost_net_busy_poll(struct vhost_net *net,

static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
struct vhost_net_virtqueue *tnvq,
+ struct vhost_buf *buf,
unsigned int *out_num, unsigned int *in_num,
struct msghdr *msghdr, bool *busyloop_intr)
{
@@ -565,10 +578,10 @@ static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
struct vhost_virtqueue *rvq = &rnvq->vq;
struct vhost_virtqueue *tvq = &tnvq->vq;

- int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
- out_num, in_num, NULL, NULL);
+ int r = vhost_get_avail_buf(tvq, buf, tvq->iov, ARRAY_SIZE(tvq->iov),
+ out_num, in_num, NULL, NULL);

- if (r == tvq->num && tvq->busyloop_timeout) {
+ if (!r && tvq->busyloop_timeout) {
/* Flush batched packets first */
if (!vhost_sock_zcopy(vhost_vq_get_backend(tvq)))
vhost_tx_batch(net, tnvq,
@@ -577,8 +590,8 @@ static int vhost_net_tx_get_vq_desc(struct vhost_net *net,

vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);

- r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
- out_num, in_num, NULL, NULL);
+ r = vhost_get_avail_buf(tvq, buf, tvq->iov, ARRAY_SIZE(tvq->iov),
+ out_num, in_num, NULL, NULL);
}

return r;
@@ -607,6 +620,7 @@ static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,

static int get_tx_bufs(struct vhost_net *net,
struct vhost_net_virtqueue *nvq,
+ struct vhost_buf *buf,
struct msghdr *msg,
unsigned int *out, unsigned int *in,
size_t *len, bool *busyloop_intr)
@@ -614,9 +628,9 @@ static int get_tx_bufs(struct vhost_net *net,
struct vhost_virtqueue *vq = &nvq->vq;
int ret;

- ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, msg, busyloop_intr);
+ ret = vhost_net_tx_get_vq_desc(net, nvq, buf, out, in, msg, busyloop_intr);

- if (ret < 0 || ret == vq->num)
+ if (ret <= 0)
return ret;

if (*in) {
@@ -761,7 +775,7 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
unsigned out, in;
- int head;
+ int ret;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
@@ -773,6 +787,7 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
int err;
int sent_pkts = 0;
bool sock_can_batch = (sock->sk->sk_sndbuf == INT_MAX);
+ struct vhost_buf buf;

do {
bool busyloop_intr = false;
@@ -780,13 +795,13 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
if (nvq->done_idx == VHOST_NET_BATCH)
vhost_tx_batch(net, nvq, sock, &msg);

- head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
- &busyloop_intr);
+ ret = get_tx_bufs(net, nvq, &buf, &msg, &out, &in, &len,
+ &busyloop_intr);
/* On error, stop handling until the next kick. */
- if (unlikely(head < 0))
+ if (unlikely(ret < 0))
break;
/* Nothing new? Wait for eventfd to tell us they refilled. */
- if (head == vq->num) {
+ if (!ret) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev,
@@ -808,7 +823,7 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
goto done;
} else if (unlikely(err != -ENOSPC)) {
vhost_tx_batch(net, nvq, sock, &msg);
- vhost_discard_vq_desc(vq, 1);
+ vhost_discard_avail_bufs(vq, &buf, 1);
vhost_net_enable_vq(net, vq);
break;
}
@@ -829,7 +844,7 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
/* TODO: Check specific error and bomb out unless ENOBUFS? */
err = sock->ops->sendmsg(sock, &msg, len);
if (unlikely(err < 0)) {
- vhost_discard_vq_desc(vq, 1);
+ vhost_discard_avail_bufs(vq, &buf, 1);
vhost_net_enable_vq(net, vq);
break;
}
@@ -837,8 +852,7 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
pr_debug("Truncated TX packet: len %d != %zd\n",
err, len);
done:
- vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
- vq->heads[nvq->done_idx].len = 0;
+ nvq->bufs[nvq->done_idx] = buf;
++nvq->done_idx;
} while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));

@@ -850,7 +864,7 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
unsigned out, in;
- int head;
+ int ret;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
@@ -864,6 +878,7 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
bool zcopy_used;
int sent_pkts = 0;
+ struct vhost_buf buf;

do {
bool busyloop_intr;
@@ -872,13 +887,13 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
vhost_zerocopy_signal_used(net, vq);

busyloop_intr = false;
- head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
- &busyloop_intr);
+ ret = get_tx_bufs(net, nvq, &buf, &msg, &out, &in, &len,
+ &busyloop_intr);
/* On error, stop handling until the next kick. */
- if (unlikely(head < 0))
+ if (unlikely(ret < 0))
break;
/* Nothing new? Wait for eventfd to tell us they refilled. */
- if (head == vq->num) {
+ if (!ret) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
@@ -897,8 +912,8 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
struct ubuf_info *ubuf;
ubuf = nvq->ubuf_info + nvq->upend_idx;

- vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
- vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
+ nvq->bufs[nvq->upend_idx] = buf;
+ nvq->bufs[nvq->upend_idx].in_len = VHOST_DMA_IN_PROGRESS;
ubuf->callback = vhost_zerocopy_callback;
ubuf->ctx = nvq->ubufs;
ubuf->desc = nvq->upend_idx;
@@ -930,17 +945,19 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
% UIO_MAXIOV;
}
- vhost_discard_vq_desc(vq, 1);
+ vhost_discard_avail_bufs(vq, &buf, 1);
vhost_net_enable_vq(net, vq);
break;
}
if (err != len)
pr_debug("Truncated TX packet: "
" len %d != %zd\n", err, len);
- if (!zcopy_used)
- vhost_add_used_and_signal(&net->dev, vq, head, 0);
- else
+ if (!zcopy_used) {
+ vhost_put_used_buf(vq, &buf);
+ vhost_signal(&net->dev, vq);
+ } else {
vhost_zerocopy_signal_used(net, vq);
+ }
vhost_net_tx_packet(net);
} while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
}
@@ -1004,7 +1021,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
int len = peek_head_len(rnvq, sk);

if (!len && rvq->busyloop_timeout) {
- /* Flush batched heads first */
+ /* Flush batched bufs first */
vhost_net_signal_used(rnvq);
/* Both tx vq and rx socket were polled here */
vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
@@ -1022,11 +1039,11 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
* @iovcount - returned count of io vectors we fill
* @log - vhost log
* @log_num - log offset
- * @quota - headcount quota, 1 for big buffer
- * returns number of buffer heads allocated, negative on error
+ * @quota - bufcount quota, 1 for big buffer
+ * returns number of buffers allocated, negative on error
*/
static int get_rx_bufs(struct vhost_virtqueue *vq,
- struct vring_used_elem *heads,
+ struct vhost_buf *bufs,
int datalen,
unsigned *iovcount,
struct vhost_log *log,
@@ -1035,30 +1052,24 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
{
unsigned int out, in;
int seg = 0;
- int headcount = 0;
- unsigned d;
+ int bufcount = 0;
int r, nlogs = 0;
/* len is always initialized before use since we are always called with
* datalen > 0.
*/
u32 uninitialized_var(len);

- while (datalen > 0 && headcount < quota) {
+ while (datalen > 0 && bufcount < quota) {
if (unlikely(seg >= UIO_MAXIOV)) {
r = -ENOBUFS;
goto err;
}
- r = vhost_get_vq_desc(vq, vq->iov + seg,
- ARRAY_SIZE(vq->iov) - seg, &out,
- &in, log, log_num);
- if (unlikely(r < 0))
+ r = vhost_get_avail_buf(vq, bufs + bufcount, vq->iov + seg,
+ ARRAY_SIZE(vq->iov) - seg, &out,
+ &in, log, log_num);
+ if (unlikely(r <= 0))
goto err;

- d = r;
- if (d == vq->num) {
- r = 0;
- goto err;
- }
if (unlikely(out || in <= 0)) {
vq_err(vq, "unexpected descriptor format for RX: "
"out %d, in %d\n", out, in);
@@ -1069,14 +1080,12 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
nlogs += *log_num;
log += *log_num;
}
- heads[headcount].id = cpu_to_vhost32(vq, d);
len = iov_length(vq->iov + seg, in);
- heads[headcount].len = cpu_to_vhost32(vq, len);
datalen -= len;
- ++headcount;
+ ++bufcount;
seg += in;
}
- heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
+ bufs[bufcount - 1].in_len = len + datalen;
*iovcount = seg;
if (unlikely(log))
*log_num = nlogs;
@@ -1086,9 +1095,9 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
r = UIO_MAXIOV + 1;
goto err;
}
- return headcount;
+ return bufcount;
err:
- vhost_discard_vq_desc(vq, headcount);
+ vhost_discard_avail_bufs(vq, bufs, bufcount);
return r;
}

@@ -1113,7 +1122,7 @@ static void handle_rx(struct vhost_net *net)
};
size_t total_len = 0;
int err, mergeable;
- s16 headcount;
+ int bufcount;
size_t vhost_hlen, sock_hlen;
size_t vhost_len, sock_len;
bool busyloop_intr = false;
@@ -1147,14 +1156,14 @@ static void handle_rx(struct vhost_net *net)
break;
sock_len += sock_hlen;
vhost_len = sock_len + vhost_hlen;
- headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
- vhost_len, &in, vq_log, &log,
- likely(mergeable) ? UIO_MAXIOV : 1);
+ bufcount = get_rx_bufs(vq, nvq->bufs + nvq->done_idx,
+ vhost_len, &in, vq_log, &log,
+ likely(mergeable) ? UIO_MAXIOV : 1);
/* On error, stop handling until the next kick. */
- if (unlikely(headcount < 0))
+ if (unlikely(bufcount < 0))
goto out;
/* OK, now we need to know about added descriptors. */
- if (!headcount) {
+ if (!bufcount) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
@@ -1171,7 +1180,7 @@ static void handle_rx(struct vhost_net *net)
if (nvq->rx_ring)
msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
/* On overrun, truncate and discard */
- if (unlikely(headcount > UIO_MAXIOV)) {
+ if (unlikely(bufcount > UIO_MAXIOV)) {
iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
err = sock->ops->recvmsg(sock, &msg,
1, MSG_DONTWAIT | MSG_TRUNC);
@@ -1195,7 +1204,7 @@ static void handle_rx(struct vhost_net *net)
if (unlikely(err != sock_len)) {
pr_debug("Discarded rx packet: "
" len %d, expected %zd\n", err, sock_len);
- vhost_discard_vq_desc(vq, headcount);
+ vhost_discard_avail_bufs(vq, nvq->bufs + nvq->done_idx, bufcount);
continue;
}
/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
@@ -1214,15 +1223,15 @@ static void handle_rx(struct vhost_net *net)
}
/* TODO: Should check and handle checksum. */

- num_buffers = cpu_to_vhost16(vq, headcount);
+ num_buffers = cpu_to_vhost16(vq, bufcount);
if (likely(mergeable) &&
copy_to_iter(&num_buffers, sizeof num_buffers,
&fixup) != sizeof num_buffers) {
vq_err(vq, "Failed num_buffers write");
- vhost_discard_vq_desc(vq, headcount);
+ vhost_discard_avail_bufs(vq, nvq->bufs + nvq->done_idx, bufcount);
goto out;
}
- nvq->done_idx += headcount;
+ nvq->done_idx += bufcount;
if (nvq->done_idx > VHOST_NET_BATCH)
vhost_net_signal_used(nvq);
if (unlikely(vq_log))
@@ -1314,6 +1323,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+ n->vqs[i].bufs = NULL;
n->vqs[i].ubufs = NULL;
n->vqs[i].ubuf_info = NULL;
n->vqs[i].upend_idx = 0;
--
MST