This adds handling of MSG_ZEROCOPY flag on transmission path, by alloc
non-linear skbuffs and filling it with user's pages.
Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
---
net/vmw_vsock/virtio_transport_common.c | 390 ++++++++++++++++++++----
1 file changed, 332 insertions(+), 58 deletions(-)
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 280497d97076..3c024d0d795c 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -37,27 +37,227 @@ virtio_transport_get_ops(struct vsock_sock *vsk)
return container_of(t, struct virtio_transport, transport);
}
-/* Returns a new packet on success, otherwise returns NULL.
- *
- * If NULL is returned, errp is set to a negative errno.
- */
-static struct sk_buff *
-virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
- size_t len,
- u32 src_cid,
- u32 src_port,
- u32 dst_cid,
- u32 dst_port)
-{
- const size_t skb_len = VIRTIO_VSOCK_SKB_HEADROOM + len;
- struct virtio_vsock_hdr *hdr;
- struct sk_buff *skb;
+static bool virtio_transport_can_zcopy(struct virtio_vsock_pkt_info *info,
+ size_t max_to_send)
+{
+ struct iov_iter *iov_iter;
+ size_t max_skb_cap;
+ size_t bytes;
+ int i;
+
+ if (!(info->flags & MSG_ZEROCOPY))
+ return false;
+
+ if (!info->msg)
+ return false;
+
+ iov_iter = &info->msg->msg_iter;
+
+ if (!iter_is_iovec(iov_iter))
+ return false;
+
+ if (iov_iter->iov_offset)
+ return false;
+
+ /* We can't send whole iov. */
+ if (iov_iter->count > max_to_send)
+ return false;
+
+ for (bytes = 0, i = 0; i < iov_iter->nr_segs; i++) {
+ const struct iovec *iovec;
+ int pages_in_elem;
+
+ iovec = &iov_iter->iov[i];
+
+ /* Base must be page aligned. */
+ if (offset_in_page(iovec->iov_base))
+ return false;
+
+ /* Only last element could have non page aligned size. */
+ if (i != (iov_iter->nr_segs - 1)) {
+ if (offset_in_page(iovec->iov_len))
+ return false;
+
+ pages_in_elem = iovec->iov_len >> PAGE_SHIFT;
+ } else {
+ pages_in_elem = round_up(iovec->iov_len, PAGE_SIZE);
+ pages_in_elem >>= PAGE_SHIFT;
+ }
+
+ bytes += (pages_in_elem * PAGE_SIZE);
+ }
+
+ /* How many bytes we can pack to single skb. Maximum packet
+ * buffer size is needed to allow vhost handle such packets,
+ * otherwise they will be dropped.
+ */
+ max_skb_cap = min((unsigned int)(MAX_SKB_FRAGS * PAGE_SIZE),
+ (unsigned int)VIRTIO_VSOCK_MAX_PKT_BUF_SIZE);
+
+ return true;
+}
+
+static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
+ struct sk_buff *skb,
+ struct iov_iter *iter,
+ bool zerocopy)
+{
+ struct ubuf_info_msgzc *uarg_zc;
+ struct ubuf_info *uarg;
+
+ uarg = msg_zerocopy_realloc(sk_vsock(vsk),
+ iov_length(iter->iov, iter->nr_segs),
+ NULL);
+
+ if (!uarg)
+ return -1;
+
+ uarg_zc = uarg_to_msgzc(uarg);
+ uarg_zc->zerocopy = zerocopy ? 1 : 0;
+
+ skb_zcopy_init(skb, uarg);
+
+ return 0;
+}
+
+static int get_iov_elem(struct iov_iter *iter, ssize_t *offset)
+{
+ int i;
+
+ *offset = iter->iov_offset;
+
+ for (i = 0; i < iter->nr_segs; i++) {
+ if (*offset - (ssize_t)iter->iov[i].iov_len < 0)
+ return i;
+
+ *offset -= iter->iov[i].iov_len;
+ }
+
+ return -1;
+}
+
+static int virtio_transport_fill_nonlinear_skb(struct sk_buff *skb,
+ struct vsock_sock *vsk,
+ struct virtio_vsock_pkt_info *info,
+ size_t payload_len)
+{
+ size_t payload_rest_len;
+ int frag_idx;
+ int err = 0;
+
+ if (!info->msg)
+ return 0;
+
+ frag_idx = 0;
+ VIRTIO_VSOCK_SKB_CB(skb)->curr_frag = 0;
+ VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
+ payload_rest_len = payload_len;
+
+ while (payload_rest_len) {
+ struct page *user_pages[MAX_SKB_FRAGS];
+ const struct iovec *iovec;
+ struct iov_iter *iter;
+ size_t last_frag_len;
+ ssize_t offs_in_iov;
+ size_t curr_iov_len;
+ size_t pages_in_seg;
+ long pinned_pages;
+ int page_idx;
+ int seg_idx;
+
+ iter = &info->msg->msg_iter;
+ seg_idx = get_iov_elem(iter, &offs_in_iov);
+ if (seg_idx < 0) {
+ err = -1;
+ break;
+ }
+
+ iovec = &iter->iov[seg_idx];
+ curr_iov_len = min(iovec->iov_len - offs_in_iov,
+ payload_rest_len);
+ pages_in_seg = curr_iov_len >> PAGE_SHIFT;
+
+ if (curr_iov_len % PAGE_SIZE) {
+ last_frag_len = curr_iov_len % PAGE_SIZE;
+ pages_in_seg++;
+ } else {
+ last_frag_len = PAGE_SIZE;
+ }
+
+ pinned_pages = pin_user_pages((unsigned long)iovec->iov_base +
+ offs_in_iov, pages_in_seg,
+ FOLL_ANON, user_pages, NULL);
+
+ if (pinned_pages != pages_in_seg) {
+ /* Unpin partially pinned pages. */
+ unpin_user_pages(user_pages, pinned_pages);
+ err = -1;
+ break;
+ }
+
+ for (page_idx = 0; page_idx < pages_in_seg; page_idx++) {
+ int frag_len = PAGE_SIZE;
+
+ if (page_idx == (pages_in_seg - 1))
+ frag_len = last_frag_len;
+
+ /* 'get_page()' as pair to 'put_page()' during
+ * this non-linear skbuff deallocation.
+ */
+ get_page(user_pages[page_idx]);
+ skb_fill_page_desc(skb, frag_idx,
+ user_pages[page_idx], 0,
+ frag_len);
+ skb_len_add(skb, frag_len);
+ frag_idx++;
+ }
+
+ iter->iov_offset += curr_iov_len;
+ payload_rest_len -= curr_iov_len;
+ }
+
+ return err;
+}
+
+static int virtio_transport_fill_linear_skb(struct sk_buff *skb,
+ struct vsock_sock *vsk,
+ struct virtio_vsock_pkt_info *info,
+ size_t len)
+{
void *payload;
int err;
- skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
- if (!skb)
- return NULL;
+ payload = skb_put(skb, len);
+ err = memcpy_from_msg(payload, info->msg, len);
+ if (err)
+ return -1;
+
+ if (msg_data_left(info->msg))
+ return 0;
+
+ if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
+ struct virtio_vsock_hdr *hdr;
+
+ hdr = virtio_vsock_hdr(skb);
+
+ hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
+
+ if (info->msg->msg_flags & MSG_EOR)
+ hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
+ }
+
+ return 0;
+}
+
+static void virtio_transport_init_hdr(struct sk_buff *skb,
+ struct virtio_vsock_pkt_info *info,
+ u32 src_cid,
+ u32 src_port,
+ u32 dst_cid,
+ u32 dst_port,
+ size_t len)
+{
+ struct virtio_vsock_hdr *hdr;
hdr = virtio_vsock_hdr(skb);
hdr->type = cpu_to_le16(info->type);
@@ -68,37 +268,6 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
hdr->dst_port = cpu_to_le32(dst_port);
hdr->flags = cpu_to_le32(info->flags);
hdr->len = cpu_to_le32(len);
-
- if (info->msg && len > 0) {
- payload = skb_put(skb, len);
- err = memcpy_from_msg(payload, info->msg, len);
- if (err)
- goto out;
-
- if (msg_data_left(info->msg) == 0 &&
- info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
- hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
-
- if (info->msg->msg_flags & MSG_EOR)
- hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
- }
- }
-
- if (info->reply)
- virtio_vsock_skb_set_reply(skb);
-
- trace_virtio_transport_alloc_pkt(src_cid, src_port,
- dst_cid, dst_port,
- len,
- info->type,
- info->op,
- info->flags);
-
- return skb;
-
-out:
- kfree_skb(skb);
- return NULL;
}
int virtio_transport_nl_skb_to_iov(struct sk_buff *skb,
@@ -209,6 +378,88 @@ static u16 virtio_transport_get_type(struct sock *sk)
return VIRTIO_VSOCK_TYPE_SEQPACKET;
}
+static void virtio_transport_unpin_skb(struct sk_buff *skb)
+{
+ int i;
+
+ if (!skb_is_nonlinear(skb))
+ return;
+
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ struct bio_vec *frag;
+ int nr_pages;
+ int page;
+
+ frag = &skb_shinfo(skb)->frags[i];
+ nr_pages = frag->bv_len / PAGE_SIZE;
+
+ if (frag->bv_len % PAGE_SIZE)
+ nr_pages++;
+
+ for (page = 0; page < nr_pages; page++)
+ unpin_user_page(&frag->bv_page[page]);
+ }
+}
+
+/* Returns a new packet on success, otherwise returns NULL.
+ *
+ * If NULL is returned, errp is set to a negative errno.
+ */
+static struct sk_buff *virtio_transport_alloc_skb(struct vsock_sock *vsk,
+ struct virtio_vsock_pkt_info *info,
+ size_t payload_len,
+ bool zcopy,
+ u32 dst_cid,
+ u32 dst_port,
+ u32 src_cid,
+ u32 src_port)
+{
+ struct sk_buff *skb;
+ size_t skb_len;
+
+ skb_len = VIRTIO_VSOCK_SKB_HEADROOM;
+
+ if (!zcopy)
+ skb_len += payload_len;
+
+ skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
+ if (!skb)
+ return NULL;
+
+ virtio_transport_init_hdr(skb, info, src_cid, src_port,
+ dst_cid, dst_port,
+ payload_len);
+
+ if (info->msg && payload_len > 0) {
+ int err;
+
+ if (zcopy) {
+ skb->destructor = virtio_transport_unpin_skb;
+ err = virtio_transport_fill_nonlinear_skb(skb, vsk, info, payload_len);
+ } else {
+ err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len);
+ }
+
+ if (err)
+ goto out;
+ }
+
+ if (info->reply)
+ virtio_vsock_skb_set_reply(skb);
+
+ trace_virtio_transport_alloc_pkt(src_cid, src_port,
+ dst_cid, dst_port,
+ payload_len,
+ info->type,
+ info->op,
+ info->flags);
+
+ return skb;
+out:
+ kfree_skb(skb);
+ return NULL;
+}
+
/* This function can only be used on connecting/connected sockets,
* since a socket assigned to a transport is required.
*
@@ -221,6 +472,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
const struct virtio_transport *t_ops;
struct virtio_vsock_sock *vvs;
u32 pkt_len = info->pkt_len;
+ bool can_zcopy = false;
+ u32 max_skb_cap;
u32 rest_len;
int ret;
@@ -230,6 +483,9 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
if (unlikely(!t_ops))
return -EFAULT;
+ if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY))
+ info->flags &= ~MSG_ZEROCOPY;
+
src_cid = t_ops->transport.get_local_cid();
src_port = vsk->local_addr.svm_port;
if (!info->remote_cid) {
@@ -249,22 +505,36 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
return pkt_len;
+ can_zcopy = virtio_transport_can_zcopy(info, pkt_len);
+ if (can_zcopy)
+ max_skb_cap = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE,
+ (MAX_SKB_FRAGS * PAGE_SIZE));
+ else
+ max_skb_cap = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
+
rest_len = pkt_len;
do {
struct sk_buff *skb;
size_t skb_len;
- skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len);
+ skb_len = min(max_skb_cap, rest_len);
- skb = virtio_transport_alloc_skb(info, skb_len,
- src_cid, src_port,
- dst_cid, dst_port);
+ skb = virtio_transport_alloc_skb(vsk, info, skb_len, can_zcopy,
+ dst_cid, dst_port,
+ src_cid, src_port);
if (!skb) {
ret = -ENOMEM;
break;
}
+ if (skb_len == rest_len &&
+ info->flags & MSG_ZEROCOPY &&
+ info->op == VIRTIO_VSOCK_OP_RW)
+ virtio_transport_init_zcopy_skb(vsk, skb,
+ &info->msg->msg_iter,
+ can_zcopy);
+
virtio_transport_inc_tx_pkt(vvs, skb);
ret = t_ops->send_pkt(skb);
@@ -945,6 +1215,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk,
.msg = msg,
.pkt_len = len,
.vsk = vsk,
+ .flags = msg->msg_flags,
};
return virtio_transport_send_pkt_info(vsk, &info);
@@ -988,6 +1259,7 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
.reply = true,
};
struct sk_buff *reply;
+ int res;
/* Send RST only if the original pkt is not a RST pkt */
if (le16_to_cpu(hdr->op) == VIRTIO_VSOCK_OP_RST)
@@ -996,15 +1268,17 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
if (!t)
return -ENOTCONN;
- reply = virtio_transport_alloc_skb(&info, 0,
- le64_to_cpu(hdr->dst_cid),
- le32_to_cpu(hdr->dst_port),
+ reply = virtio_transport_alloc_skb(NULL, &info, 0, false,
le64_to_cpu(hdr->src_cid),
- le32_to_cpu(hdr->src_port));
+ le32_to_cpu(hdr->src_port),
+ le64_to_cpu(hdr->dst_cid),
+ le32_to_cpu(hdr->dst_port));
if (!reply)
return -ENOMEM;
- return t->send_pkt(reply);
+ res = t->send_pkt(reply);
+
+ return res;
}
/* This function should be called with sk_lock held and SOCK_DONE set */
--
2.25.1
