| Message ID | 20230603204939.1598818-6-AVKrasnov@sberdevices.ru (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | vsock: MSG_ZEROCOPY flag support | expand |
On Sat, Jun 03, 2023 at 11:49:27PM +0300, Arseniy Krasnov wrote: >This adds handling of MSG_ZEROCOPY flag on transmission path: if this >flag is set and zerocopy transmission is possible, then non-linear skb >will be created and filled with the pages of user's buffer. Pages of >user's buffer are locked in memory by 'get_user_pages()'. > >Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >--- > net/vmw_vsock/virtio_transport_common.c | 270 ++++++++++++++++++------ > 1 file changed, 208 insertions(+), 62 deletions(-) > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index 0de562c1dc4b..f1ec38c72db7 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -37,27 +37,100 @@ 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; >+ >+ if (!info->msg) >+ return false; >+ >+ iov_iter = &info->msg->msg_iter; >+ >+ /* Data is simple buffer. */ >+ if (iter_is_ubuf(iov_iter)) >+ return true; >+ >+ 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; >+ >+ return true; >+} >+ >+static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk, >+ struct sk_buff *skb, >+ struct msghdr *msg, >+ bool zerocopy) >+{ >+ struct ubuf_info *uarg; >+ >+ if (msg->msg_ubuf) { >+ uarg = msg->msg_ubuf; >+ net_zcopy_get(uarg); >+ } else { >+ struct iov_iter *iter = &msg->msg_iter; >+ struct ubuf_info_msgzc *uarg_zc; >+ int len; >+ >+ /* Only ITER_IOVEC or ITER_UBUF are allowed and >+ * checked before. >+ */ >+ if (iter_is_iovec(iter)) >+ len = iov_length(iter->__iov, iter->nr_segs); >+ else >+ len = iter->count; >+ >+ uarg = msg_zerocopy_realloc(sk_vsock(vsk), >+ len, >+ 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 virtio_transport_fill_linear_skb(struct sk_buff *skb, >+ struct vsock_sock *vsk, `vsk` seems unused >+ 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; >+ >+ 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); >@@ -68,42 +141,6 @@ 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); >- >- if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) { >- WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n"); >- goto out; >- } >- >- return skb; >- >-out: >- kfree_skb(skb); >- return NULL; > } > > static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, >@@ -214,6 +251,85 @@ static u16 virtio_transport_get_type(struct sock *sk) > return VIRTIO_VSOCK_TYPE_SEQPACKET; > } > >+/* Returns a new packet on success, otherwise returns NULL. >+ * >+ * If NULL is returned, errp is set to a negative errno. I had noticed this in Bobby's patches, I think it's an old comment we left around. >+ */ >+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); >+ >+ /* Set owner here, because '__zerocopy_sg_from_iter()' uses >+ * owner of skb without check to update 'sk_wmem_alloc'. >+ */ >+ if (vsk) >+ skb_set_owner_w(skb, sk_vsock(vsk)); why we are moving from skb_set_owner_sk_safe() to skb_set_owner_w()? We should mention this in the commit description. >+ >+ if (info->msg && payload_len > 0) { >+ int err; >+ >+ if (zcopy) { >+ err = __zerocopy_sg_from_iter(info->msg, NULL, skb, >+ &info->msg->msg_iter, >+ payload_len); >+ } else { >+ err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len); >+ } >+ >+ if (err) >+ goto out; >+ >+ VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0; >+ >+ if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >+ struct virtio_vsock_hdr *hdr; >+ >+ hdr = virtio_vsock_hdr(skb); Just `struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);` should be fine. >+ >+ 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, >+ 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. > * >@@ -226,6 +342,8 @@ 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; > >@@ -254,22 +372,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, > if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) > return pkt_len; > >+ /* If zerocopy is not enabled by 'setsockopt()', we behave as >+ * there is no MSG_ZEROCOPY flag set. >+ */ >+ if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) >+ info->flags &= ~MSG_ZEROCOPY; >+ >+ if (info->flags & MSG_ZEROCOPY) >+ 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; >+ We use `len` very often, what about `max_skb_len`? > 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; > } > >+ /* This is last skb to send this portion of data. */ >+ if (skb_len == rest_len && >+ info->flags & MSG_ZEROCOPY && >+ info->op == VIRTIO_VSOCK_OP_RW) { >+ if (virtio_transport_init_zcopy_skb(vsk, skb, >+ info->msg, >+ can_zcopy)) { >+ ret = -ENOMEM; >+ break; >+ } >+ } >+ > virtio_transport_inc_tx_pkt(vvs, skb); > > ret = t_ops->send_pkt(skb); >@@ -884,6 +1029,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk, > .msg = msg, > .pkt_len = len, > .vsk = vsk, >+ .flags = msg->msg_flags, These flags then get copied into the virtio_vsock_hdr, which I don't think is a good idea. Why not using directly info->msg->msg_flags? > }; > > return virtio_transport_send_pkt_info(vsk, &info); >@@ -935,11 +1081,11 @@ 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; > >-- >2.25.1 >
On 26.06.2023 19:03, Stefano Garzarella wrote: > On Sat, Jun 03, 2023 at 11:49:27PM +0300, Arseniy Krasnov wrote: >> This adds handling of MSG_ZEROCOPY flag on transmission path: if this >> flag is set and zerocopy transmission is possible, then non-linear skb >> will be created and filled with the pages of user's buffer. Pages of >> user's buffer are locked in memory by 'get_user_pages()'. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >> --- >> net/vmw_vsock/virtio_transport_common.c | 270 ++++++++++++++++++------ >> 1 file changed, 208 insertions(+), 62 deletions(-) >> >> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >> index 0de562c1dc4b..f1ec38c72db7 100644 >> --- a/net/vmw_vsock/virtio_transport_common.c >> +++ b/net/vmw_vsock/virtio_transport_common.c >> @@ -37,27 +37,100 @@ 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; >> + >> + if (!info->msg) >> + return false; >> + >> + iov_iter = &info->msg->msg_iter; >> + >> + /* Data is simple buffer. */ >> + if (iter_is_ubuf(iov_iter)) >> + return true; >> + >> + 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; >> + >> + return true; >> +} >> + >> +static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk, >> + struct sk_buff *skb, >> + struct msghdr *msg, >> + bool zerocopy) >> +{ >> + struct ubuf_info *uarg; >> + >> + if (msg->msg_ubuf) { >> + uarg = msg->msg_ubuf; >> + net_zcopy_get(uarg); >> + } else { >> + struct iov_iter *iter = &msg->msg_iter; >> + struct ubuf_info_msgzc *uarg_zc; >> + int len; >> + >> + /* Only ITER_IOVEC or ITER_UBUF are allowed and >> + * checked before. >> + */ >> + if (iter_is_iovec(iter)) >> + len = iov_length(iter->__iov, iter->nr_segs); >> + else >> + len = iter->count; >> + >> + uarg = msg_zerocopy_realloc(sk_vsock(vsk), >> + len, >> + 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 virtio_transport_fill_linear_skb(struct sk_buff *skb, >> + struct vsock_sock *vsk, > > `vsk` seems unused > >> + 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; >> + >> + 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); >> @@ -68,42 +141,6 @@ 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); >> - >> - if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) { >> - WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n"); >> - goto out; >> - } >> - >> - return skb; >> - >> -out: >> - kfree_skb(skb); >> - return NULL; >> } >> >> static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, >> @@ -214,6 +251,85 @@ static u16 virtio_transport_get_type(struct sock *sk) >> return VIRTIO_VSOCK_TYPE_SEQPACKET; >> } >> >> +/* Returns a new packet on success, otherwise returns NULL. >> + * >> + * If NULL is returned, errp is set to a negative errno. > > I had noticed this in Bobby's patches, I think it's an old comment we > left around. > >> + */ >> +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); >> + >> + /* Set owner here, because '__zerocopy_sg_from_iter()' uses >> + * owner of skb without check to update 'sk_wmem_alloc'. >> + */ >> + if (vsk) >> + skb_set_owner_w(skb, sk_vsock(vsk)); > > why we are moving from skb_set_owner_sk_safe() to skb_set_owner_w()? > > We should mention this in the commit description. > >> + >> + if (info->msg && payload_len > 0) { >> + int err; >> + >> + if (zcopy) { >> + err = __zerocopy_sg_from_iter(info->msg, NULL, skb, >> + &info->msg->msg_iter, >> + payload_len); >> + } else { >> + err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len); >> + } >> + >> + if (err) >> + goto out; >> + >> + VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0; >> + >> + if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >> + struct virtio_vsock_hdr *hdr; >> + >> + hdr = virtio_vsock_hdr(skb); > > Just `struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);` should be > fine. > >> + >> + 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, >> + 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. >> * >> @@ -226,6 +342,8 @@ 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; >> >> @@ -254,22 +372,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) >> return pkt_len; >> >> + /* If zerocopy is not enabled by 'setsockopt()', we behave as >> + * there is no MSG_ZEROCOPY flag set. >> + */ >> + if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) >> + info->flags &= ~MSG_ZEROCOPY; >> + >> + if (info->flags & MSG_ZEROCOPY) >> + 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; >> + > > We use `len` very often, what about `max_skb_len`? > >> 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; >> } >> >> + /* This is last skb to send this portion of data. */ >> + if (skb_len == rest_len && >> + info->flags & MSG_ZEROCOPY && >> + info->op == VIRTIO_VSOCK_OP_RW) { >> + if (virtio_transport_init_zcopy_skb(vsk, skb, >> + info->msg, >> + can_zcopy)) { >> + ret = -ENOMEM; >> + break; >> + } >> + } >> + >> virtio_transport_inc_tx_pkt(vvs, skb); >> >> ret = t_ops->send_pkt(skb); >> @@ -884,6 +1029,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk, >> .msg = msg, >> .pkt_len = len, >> .vsk = vsk, >> + .flags = msg->msg_flags, > > These flags then get copied into the virtio_vsock_hdr, which I don't > think is a good idea. > > Why not using directly info->msg->msg_flags? Ops, yes, it's a bug, You're right, this is really wrong as there are two different sets of flags - MSG_XXX passed to syscall and flags in the header of packet. Thanks, Arseniy > >> }; >> >> return virtio_transport_send_pkt_info(vsk, &info); >> @@ -935,11 +1081,11 @@ 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; >> >> -- >> 2.25.1 >> >
On Tue, Jun 27, 2023 at 07:41:51AM +0300, Arseniy Krasnov wrote: > > >On 26.06.2023 19:03, Stefano Garzarella wrote: >> On Sat, Jun 03, 2023 at 11:49:27PM +0300, Arseniy Krasnov wrote: >>> This adds handling of MSG_ZEROCOPY flag on transmission path: if this >>> flag is set and zerocopy transmission is possible, then non-linear skb >>> will be created and filled with the pages of user's buffer. Pages of >>> user's buffer are locked in memory by 'get_user_pages()'. >>> >>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >>> --- >>> net/vmw_vsock/virtio_transport_common.c | 270 ++++++++++++++++++------ >>> 1 file changed, 208 insertions(+), 62 deletions(-) >>> >>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>> index 0de562c1dc4b..f1ec38c72db7 100644 >>> --- a/net/vmw_vsock/virtio_transport_common.c >>> +++ b/net/vmw_vsock/virtio_transport_common.c >>> @@ -37,27 +37,100 @@ 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; >>> + >>> + if (!info->msg) >>> + return false; >>> + >>> + iov_iter = &info->msg->msg_iter; >>> + >>> + /* Data is simple buffer. */ >>> + if (iter_is_ubuf(iov_iter)) >>> + return true; >>> + >>> + 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; >>> + >>> + return true; >>> +} >>> + >>> +static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk, >>> + struct sk_buff *skb, >>> + struct msghdr *msg, >>> + bool zerocopy) >>> +{ >>> + struct ubuf_info *uarg; >>> + >>> + if (msg->msg_ubuf) { >>> + uarg = msg->msg_ubuf; >>> + net_zcopy_get(uarg); >>> + } else { >>> + struct iov_iter *iter = &msg->msg_iter; >>> + struct ubuf_info_msgzc *uarg_zc; >>> + int len; >>> + >>> + /* Only ITER_IOVEC or ITER_UBUF are allowed and >>> + * checked before. >>> + */ >>> + if (iter_is_iovec(iter)) >>> + len = iov_length(iter->__iov, iter->nr_segs); >>> + else >>> + len = iter->count; >>> + >>> + uarg = msg_zerocopy_realloc(sk_vsock(vsk), >>> + len, >>> + 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 virtio_transport_fill_linear_skb(struct sk_buff *skb, >>> + struct vsock_sock *vsk, >> >> `vsk` seems unused >> >>> + 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; >>> + >>> + 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); >>> @@ -68,42 +141,6 @@ 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); >>> - >>> - if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) { >>> - WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n"); >>> - goto out; >>> - } >>> - >>> - return skb; >>> - >>> -out: >>> - kfree_skb(skb); >>> - return NULL; >>> } >>> >>> static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, >>> @@ -214,6 +251,85 @@ static u16 virtio_transport_get_type(struct sock *sk) >>> return VIRTIO_VSOCK_TYPE_SEQPACKET; >>> } >>> >>> +/* Returns a new packet on success, otherwise returns NULL. >>> + * >>> + * If NULL is returned, errp is set to a negative errno. >> >> I had noticed this in Bobby's patches, I think it's an old comment we >> left around. >> >>> + */ >>> +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); >>> + >>> + /* Set owner here, because '__zerocopy_sg_from_iter()' uses >>> + * owner of skb without check to update 'sk_wmem_alloc'. >>> + */ >>> + if (vsk) >>> + skb_set_owner_w(skb, sk_vsock(vsk)); >> >> why we are moving from skb_set_owner_sk_safe() to skb_set_owner_w()? >> >> We should mention this in the commit description. >> >>> + >>> + if (info->msg && payload_len > 0) { >>> + int err; >>> + >>> + if (zcopy) { >>> + err = __zerocopy_sg_from_iter(info->msg, NULL, skb, >>> + &info->msg->msg_iter, >>> + payload_len); >>> + } else { >>> + err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len); >>> + } >>> + >>> + if (err) >>> + goto out; >>> + >>> + VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0; >>> + >>> + if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >>> + struct virtio_vsock_hdr *hdr; >>> + >>> + hdr = virtio_vsock_hdr(skb); >> >> Just `struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);` should be >> fine. >> >>> + >>> + 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, >>> + 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. >>> * >>> @@ -226,6 +342,8 @@ 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; >>> >>> @@ -254,22 +372,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >>> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) >>> return pkt_len; >>> >>> + /* If zerocopy is not enabled by 'setsockopt()', we behave as >>> + * there is no MSG_ZEROCOPY flag set. >>> + */ >>> + if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) >>> + info->flags &= ~MSG_ZEROCOPY; >>> + >>> + if (info->flags & MSG_ZEROCOPY) >>> + 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; >>> + >> >> We use `len` very often, what about `max_skb_len`? >> >>> 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; >>> } >>> >>> + /* This is last skb to send this portion of data. */ >>> + if (skb_len == rest_len && >>> + info->flags & MSG_ZEROCOPY && >>> + info->op == VIRTIO_VSOCK_OP_RW) { >>> + if (virtio_transport_init_zcopy_skb(vsk, skb, >>> + info->msg, >>> + can_zcopy)) { >>> + ret = -ENOMEM; >>> + break; >>> + } >>> + } >>> + >>> virtio_transport_inc_tx_pkt(vvs, skb); >>> >>> ret = t_ops->send_pkt(skb); >>> @@ -884,6 +1029,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk, >>> .msg = msg, >>> .pkt_len = len, >>> .vsk = vsk, >>> + .flags = msg->msg_flags, >> >> These flags then get copied into the virtio_vsock_hdr, which I don't >> think is a good idea. >> >> Why not using directly info->msg->msg_flags? > >Ops, yes, it's a bug, You're right, this is really wrong as there are two different >sets of flags - MSG_XXX passed to syscall and flags in the header of packet. Yep. What about the moving from skb_set_owner_sk_safe() to skb_set_owner_w()? Was it voluntary? If so, can you explain why? Thanks, Stefano
On 27.06.2023 10:50, Stefano Garzarella wrote: > On Tue, Jun 27, 2023 at 07:41:51AM +0300, Arseniy Krasnov wrote: >> >> >> On 26.06.2023 19:03, Stefano Garzarella wrote: >>> On Sat, Jun 03, 2023 at 11:49:27PM +0300, Arseniy Krasnov wrote: >>>> This adds handling of MSG_ZEROCOPY flag on transmission path: if this >>>> flag is set and zerocopy transmission is possible, then non-linear skb >>>> will be created and filled with the pages of user's buffer. Pages of >>>> user's buffer are locked in memory by 'get_user_pages()'. >>>> >>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >>>> --- >>>> net/vmw_vsock/virtio_transport_common.c | 270 ++++++++++++++++++------ >>>> 1 file changed, 208 insertions(+), 62 deletions(-) >>>> >>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>>> index 0de562c1dc4b..f1ec38c72db7 100644 >>>> --- a/net/vmw_vsock/virtio_transport_common.c >>>> +++ b/net/vmw_vsock/virtio_transport_common.c >>>> @@ -37,27 +37,100 @@ 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; >>>> + >>>> + if (!info->msg) >>>> + return false; >>>> + >>>> + iov_iter = &info->msg->msg_iter; >>>> + >>>> + /* Data is simple buffer. */ >>>> + if (iter_is_ubuf(iov_iter)) >>>> + return true; >>>> + >>>> + 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; >>>> + >>>> + return true; >>>> +} >>>> + >>>> +static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk, >>>> + struct sk_buff *skb, >>>> + struct msghdr *msg, >>>> + bool zerocopy) >>>> +{ >>>> + struct ubuf_info *uarg; >>>> + >>>> + if (msg->msg_ubuf) { >>>> + uarg = msg->msg_ubuf; >>>> + net_zcopy_get(uarg); >>>> + } else { >>>> + struct iov_iter *iter = &msg->msg_iter; >>>> + struct ubuf_info_msgzc *uarg_zc; >>>> + int len; >>>> + >>>> + /* Only ITER_IOVEC or ITER_UBUF are allowed and >>>> + * checked before. >>>> + */ >>>> + if (iter_is_iovec(iter)) >>>> + len = iov_length(iter->__iov, iter->nr_segs); >>>> + else >>>> + len = iter->count; >>>> + >>>> + uarg = msg_zerocopy_realloc(sk_vsock(vsk), >>>> + len, >>>> + 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 virtio_transport_fill_linear_skb(struct sk_buff *skb, >>>> + struct vsock_sock *vsk, >>> >>> `vsk` seems unused >>> >>>> + 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; >>>> + >>>> + 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); >>>> @@ -68,42 +141,6 @@ 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); >>>> - >>>> - if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) { >>>> - WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n"); >>>> - goto out; >>>> - } >>>> - >>>> - return skb; >>>> - >>>> -out: >>>> - kfree_skb(skb); >>>> - return NULL; >>>> } >>>> >>>> static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, >>>> @@ -214,6 +251,85 @@ static u16 virtio_transport_get_type(struct sock *sk) >>>> return VIRTIO_VSOCK_TYPE_SEQPACKET; >>>> } >>>> >>>> +/* Returns a new packet on success, otherwise returns NULL. >>>> + * >>>> + * If NULL is returned, errp is set to a negative errno. >>> >>> I had noticed this in Bobby's patches, I think it's an old comment we >>> left around. >>> >>>> + */ >>>> +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); >>>> + >>>> + /* Set owner here, because '__zerocopy_sg_from_iter()' uses >>>> + * owner of skb without check to update 'sk_wmem_alloc'. >>>> + */ >>>> + if (vsk) >>>> + skb_set_owner_w(skb, sk_vsock(vsk)); >>> >>> why we are moving from skb_set_owner_sk_safe() to skb_set_owner_w()? >>> >>> We should mention this in the commit description. >>> >>>> + >>>> + if (info->msg && payload_len > 0) { >>>> + int err; >>>> + >>>> + if (zcopy) { >>>> + err = __zerocopy_sg_from_iter(info->msg, NULL, skb, >>>> + &info->msg->msg_iter, >>>> + payload_len); >>>> + } else { >>>> + err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len); >>>> + } >>>> + >>>> + if (err) >>>> + goto out; >>>> + >>>> + VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0; >>>> + >>>> + if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >>>> + struct virtio_vsock_hdr *hdr; >>>> + >>>> + hdr = virtio_vsock_hdr(skb); >>> >>> Just `struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);` should be >>> fine. >>> >>>> + >>>> + 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, >>>> + 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. >>>> * >>>> @@ -226,6 +342,8 @@ 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; >>>> >>>> @@ -254,22 +372,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >>>> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) >>>> return pkt_len; >>>> >>>> + /* If zerocopy is not enabled by 'setsockopt()', we behave as >>>> + * there is no MSG_ZEROCOPY flag set. >>>> + */ >>>> + if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) >>>> + info->flags &= ~MSG_ZEROCOPY; >>>> + >>>> + if (info->flags & MSG_ZEROCOPY) >>>> + 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; >>>> + >>> >>> We use `len` very often, what about `max_skb_len`? >>> >>>> 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; >>>> } >>>> >>>> + /* This is last skb to send this portion of data. */ >>>> + if (skb_len == rest_len && >>>> + info->flags & MSG_ZEROCOPY && >>>> + info->op == VIRTIO_VSOCK_OP_RW) { >>>> + if (virtio_transport_init_zcopy_skb(vsk, skb, >>>> + info->msg, >>>> + can_zcopy)) { >>>> + ret = -ENOMEM; >>>> + break; >>>> + } >>>> + } >>>> + >>>> virtio_transport_inc_tx_pkt(vvs, skb); >>>> >>>> ret = t_ops->send_pkt(skb); >>>> @@ -884,6 +1029,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk, >>>> .msg = msg, >>>> .pkt_len = len, >>>> .vsk = vsk, >>>> + .flags = msg->msg_flags, >>> >>> These flags then get copied into the virtio_vsock_hdr, which I don't >>> think is a good idea. >>> >>> Why not using directly info->msg->msg_flags? >> >> Ops, yes, it's a bug, You're right, this is really wrong as there are two different >> sets of flags - MSG_XXX passed to syscall and flags in the header of packet. > > Yep. > > What about the moving from skb_set_owner_sk_safe() to skb_set_owner_w()? > Was it voluntary? If so, can you explain why? Sure! here is what happens: difference between these functions is that 'skb_set_owner_w()' sets another destructor - 'sock_wfree()': https://elixir.bootlin.com/linux/v6.4/source/net/core/sock.c#L2408 This destructor also updates 'sk->sk_wmem_alloc' during skb freeing. Why this is needed? Because '__zerocopy_sg_from_iter()' updates 'sk_wmem_alloc' if socket is NOT SOCK_STREAM or socket was NOT passed as input argument (it is not obvious why, but it is so): https://elixir.bootlin.com/linux/latest/source/net/core/datagram.c#L646 So to support both types of sockets (seqpacket and stream) I decided to try pass NULL always as socket argument to '__zerocopy_sg_from_iter()', with this 'sk_wmem_alloc' will be always updated in '__zerocopy_sg_from_iter()' and then we decrease 'sk_wmem_alloc' in 'sock_wfree()'. May be this looks strange - I tried to understand logic of this code in '__zerocopy_sg_from_iter()', but it requires more deep analysis. Anyway it works:) Thanks, Arseniy > > > Thanks, > Stefano >
On Tue, Jun 27, 2023 at 11:22:52AM +0300, Arseniy Krasnov wrote: > > >On 27.06.2023 10:50, Stefano Garzarella wrote: >> On Tue, Jun 27, 2023 at 07:41:51AM +0300, Arseniy Krasnov wrote: >>> >>> >>> On 26.06.2023 19:03, Stefano Garzarella wrote: >>>> On Sat, Jun 03, 2023 at 11:49:27PM +0300, Arseniy Krasnov wrote: >>>>> This adds handling of MSG_ZEROCOPY flag on transmission path: if this >>>>> flag is set and zerocopy transmission is possible, then non-linear skb >>>>> will be created and filled with the pages of user's buffer. Pages of >>>>> user's buffer are locked in memory by 'get_user_pages()'. >>>>> >>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >>>>> --- >>>>> net/vmw_vsock/virtio_transport_common.c | 270 ++++++++++++++++++------ >>>>> 1 file changed, 208 insertions(+), 62 deletions(-) >>>>> >>>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>>>> index 0de562c1dc4b..f1ec38c72db7 100644 >>>>> --- a/net/vmw_vsock/virtio_transport_common.c >>>>> +++ b/net/vmw_vsock/virtio_transport_common.c >>>>> @@ -37,27 +37,100 @@ 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; >>>>> + >>>>> + if (!info->msg) >>>>> + return false; >>>>> + >>>>> + iov_iter = &info->msg->msg_iter; >>>>> + >>>>> + /* Data is simple buffer. */ >>>>> + if (iter_is_ubuf(iov_iter)) >>>>> + return true; >>>>> + >>>>> + 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; >>>>> + >>>>> + return true; >>>>> +} >>>>> + >>>>> +static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk, >>>>> + struct sk_buff *skb, >>>>> + struct msghdr *msg, >>>>> + bool zerocopy) >>>>> +{ >>>>> + struct ubuf_info *uarg; >>>>> + >>>>> + if (msg->msg_ubuf) { >>>>> + uarg = msg->msg_ubuf; >>>>> + net_zcopy_get(uarg); >>>>> + } else { >>>>> + struct iov_iter *iter = &msg->msg_iter; >>>>> + struct ubuf_info_msgzc *uarg_zc; >>>>> + int len; >>>>> + >>>>> + /* Only ITER_IOVEC or ITER_UBUF are allowed and >>>>> + * checked before. >>>>> + */ >>>>> + if (iter_is_iovec(iter)) >>>>> + len = iov_length(iter->__iov, iter->nr_segs); >>>>> + else >>>>> + len = iter->count; >>>>> + >>>>> + uarg = msg_zerocopy_realloc(sk_vsock(vsk), >>>>> + len, >>>>> + 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 virtio_transport_fill_linear_skb(struct sk_buff *skb, >>>>> + struct vsock_sock *vsk, >>>> >>>> `vsk` seems unused >>>> >>>>> + 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; >>>>> + >>>>> + 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); >>>>> @@ -68,42 +141,6 @@ 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); >>>>> - >>>>> - if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) { >>>>> - WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n"); >>>>> - goto out; >>>>> - } >>>>> - >>>>> - return skb; >>>>> - >>>>> -out: >>>>> - kfree_skb(skb); >>>>> - return NULL; >>>>> } >>>>> >>>>> static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, >>>>> @@ -214,6 +251,85 @@ static u16 virtio_transport_get_type(struct sock *sk) >>>>> return VIRTIO_VSOCK_TYPE_SEQPACKET; >>>>> } >>>>> >>>>> +/* Returns a new packet on success, otherwise returns NULL. >>>>> + * >>>>> + * If NULL is returned, errp is set to a negative errno. >>>> >>>> I had noticed this in Bobby's patches, I think it's an old comment we >>>> left around. >>>> >>>>> + */ >>>>> +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); >>>>> + >>>>> + /* Set owner here, because '__zerocopy_sg_from_iter()' uses >>>>> + * owner of skb without check to update 'sk_wmem_alloc'. >>>>> + */ >>>>> + if (vsk) >>>>> + skb_set_owner_w(skb, sk_vsock(vsk)); >>>> >>>> why we are moving from skb_set_owner_sk_safe() to skb_set_owner_w()? >>>> >>>> We should mention this in the commit description. >>>> >>>>> + >>>>> + if (info->msg && payload_len > 0) { >>>>> + int err; >>>>> + >>>>> + if (zcopy) { >>>>> + err = __zerocopy_sg_from_iter(info->msg, NULL, skb, >>>>> + &info->msg->msg_iter, >>>>> + payload_len); >>>>> + } else { >>>>> + err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len); >>>>> + } >>>>> + >>>>> + if (err) >>>>> + goto out; >>>>> + >>>>> + VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0; >>>>> + >>>>> + if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >>>>> + struct virtio_vsock_hdr *hdr; >>>>> + >>>>> + hdr = virtio_vsock_hdr(skb); >>>> >>>> Just `struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);` should be >>>> fine. >>>> >>>>> + >>>>> + 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, >>>>> + 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. >>>>> * >>>>> @@ -226,6 +342,8 @@ 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; >>>>> >>>>> @@ -254,22 +372,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >>>>> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) >>>>> return pkt_len; >>>>> >>>>> + /* If zerocopy is not enabled by 'setsockopt()', we behave as >>>>> + * there is no MSG_ZEROCOPY flag set. >>>>> + */ >>>>> + if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) >>>>> + info->flags &= ~MSG_ZEROCOPY; >>>>> + >>>>> + if (info->flags & MSG_ZEROCOPY) >>>>> + 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; >>>>> + >>>> >>>> We use `len` very often, what about `max_skb_len`? >>>> >>>>> 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; >>>>> } >>>>> >>>>> + /* This is last skb to send this portion of data. */ >>>>> + if (skb_len == rest_len && >>>>> + info->flags & MSG_ZEROCOPY && >>>>> + info->op == VIRTIO_VSOCK_OP_RW) { >>>>> + if (virtio_transport_init_zcopy_skb(vsk, skb, >>>>> + info->msg, >>>>> + can_zcopy)) { >>>>> + ret = -ENOMEM; >>>>> + break; >>>>> + } >>>>> + } >>>>> + >>>>> virtio_transport_inc_tx_pkt(vvs, skb); >>>>> >>>>> ret = t_ops->send_pkt(skb); >>>>> @@ -884,6 +1029,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk, >>>>> .msg = msg, >>>>> .pkt_len = len, >>>>> .vsk = vsk, >>>>> + .flags = msg->msg_flags, >>>> >>>> These flags then get copied into the virtio_vsock_hdr, which I don't >>>> think is a good idea. >>>> >>>> Why not using directly info->msg->msg_flags? >>> >>> Ops, yes, it's a bug, You're right, this is really wrong as there are two different >>> sets of flags - MSG_XXX passed to syscall and flags in the header of packet. >> >> Yep. >> >> What about the moving from skb_set_owner_sk_safe() to skb_set_owner_w()? >> Was it voluntary? If so, can you explain why? > >Sure! here is what happens: difference between these functions is that 'skb_set_owner_w()' >sets another destructor - 'sock_wfree()': > >https://elixir.bootlin.com/linux/v6.4/source/net/core/sock.c#L2408 > >This destructor also updates 'sk->sk_wmem_alloc' during skb freeing. Why this is needed? >Because '__zerocopy_sg_from_iter()' updates 'sk_wmem_alloc' if socket is NOT SOCK_STREAM >or socket was NOT passed as input argument (it is not obvious why, but it is so): > >https://elixir.bootlin.com/linux/latest/source/net/core/datagram.c#L646 > >So to support both types of sockets (seqpacket and stream) I decided to try pass NULL always >as socket argument to '__zerocopy_sg_from_iter()', with this 'sk_wmem_alloc' will be always >updated in '__zerocopy_sg_from_iter()' and then we decrease 'sk_wmem_alloc' in 'sock_wfree()'. > >May be this looks strange - I tried to understand logic of this code in '__zerocopy_sg_from_iter()', >but it requires more deep analysis. Anyway it works:) Yep, it should require also more analysis on my side :-) Please document it in the commit description, so if we will find any issue in the future, we know why we did this change. Thanks, Stefano
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 0de562c1dc4b..f1ec38c72db7 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -37,27 +37,100 @@ 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; + + if (!info->msg) + return false; + + iov_iter = &info->msg->msg_iter; + + /* Data is simple buffer. */ + if (iter_is_ubuf(iov_iter)) + return true; + + 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; + + return true; +} + +static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk, + struct sk_buff *skb, + struct msghdr *msg, + bool zerocopy) +{ + struct ubuf_info *uarg; + + if (msg->msg_ubuf) { + uarg = msg->msg_ubuf; + net_zcopy_get(uarg); + } else { + struct iov_iter *iter = &msg->msg_iter; + struct ubuf_info_msgzc *uarg_zc; + int len; + + /* Only ITER_IOVEC or ITER_UBUF are allowed and + * checked before. + */ + if (iter_is_iovec(iter)) + len = iov_length(iter->__iov, iter->nr_segs); + else + len = iter->count; + + uarg = msg_zerocopy_realloc(sk_vsock(vsk), + len, + 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 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; + + 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); @@ -68,42 +141,6 @@ 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); - - if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) { - WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n"); - goto out; - } - - return skb; - -out: - kfree_skb(skb); - return NULL; } static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, @@ -214,6 +251,85 @@ static u16 virtio_transport_get_type(struct sock *sk) return VIRTIO_VSOCK_TYPE_SEQPACKET; } +/* 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); + + /* Set owner here, because '__zerocopy_sg_from_iter()' uses + * owner of skb without check to update 'sk_wmem_alloc'. + */ + if (vsk) + skb_set_owner_w(skb, sk_vsock(vsk)); + + if (info->msg && payload_len > 0) { + int err; + + if (zcopy) { + err = __zerocopy_sg_from_iter(info->msg, NULL, skb, + &info->msg->msg_iter, + payload_len); + } else { + err = virtio_transport_fill_linear_skb(skb, vsk, info, payload_len); + } + + if (err) + goto out; + + VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 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); + } + } + + 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. * @@ -226,6 +342,8 @@ 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; @@ -254,22 +372,49 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) return pkt_len; + /* If zerocopy is not enabled by 'setsockopt()', we behave as + * there is no MSG_ZEROCOPY flag set. + */ + if (!sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) + info->flags &= ~MSG_ZEROCOPY; + + if (info->flags & MSG_ZEROCOPY) + 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; } + /* This is last skb to send this portion of data. */ + if (skb_len == rest_len && + info->flags & MSG_ZEROCOPY && + info->op == VIRTIO_VSOCK_OP_RW) { + if (virtio_transport_init_zcopy_skb(vsk, skb, + info->msg, + can_zcopy)) { + ret = -ENOMEM; + break; + } + } + virtio_transport_inc_tx_pkt(vvs, skb); ret = t_ops->send_pkt(skb); @@ -884,6 +1029,7 @@ 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); @@ -935,11 +1081,11 @@ 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;
This adds handling of MSG_ZEROCOPY flag on transmission path: if this flag is set and zerocopy transmission is possible, then non-linear skb will be created and filled with the pages of user's buffer. Pages of user's buffer are locked in memory by 'get_user_pages()'. Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> --- net/vmw_vsock/virtio_transport_common.c | 270 ++++++++++++++++++------ 1 file changed, 208 insertions(+), 62 deletions(-)