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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "Michael S. Tsirkin" , Jason Wang , Bobby Eshleman CC: , , , , , , , Arseniy Krasnov Subject: [RFC PATCH v3 05/17] vsock/virtio: MSG_ZEROCOPY flag support Date: Mon, 22 May 2023 10:39:38 +0300 Message-ID: <20230522073950.3574171-6-AVKrasnov@sberdevices.ru> X-Mailer: git-send-email 2.35.0 In-Reply-To: <20230522073950.3574171-1-AVKrasnov@sberdevices.ru> References: <20230522073950.3574171-1-AVKrasnov@sberdevices.ru> MIME-Version: 1.0 X-Originating-IP: [172.16.1.6] X-ClientProxiedBy: S-MS-EXCH02.sberdevices.ru (172.16.1.5) To S-MS-EXCH01.sberdevices.ru (172.16.1.4) X-KSMG-Rule-ID: 4 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Status: not scanned, disabled by settings X-KSMG-AntiSpam-Interceptor-Info: not scanned X-KSMG-AntiPhishing: not scanned, disabled by settings X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 1.1.2.30, bases: 2023/05/22 04:49:00 #21364689 X-KSMG-AntiVirus-Status: Clean, skipped X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1766580003130003746?= X-GMAIL-MSGID: =?utf-8?q?1766580003130003746?= 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 --- net/vmw_vsock/virtio_transport_common.c | 305 +++++++++++++++++++----- 1 file changed, 243 insertions(+), 62 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 9854f48a0544..5acf824afe41 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -37,73 +37,161 @@ 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; - void *payload; - int err; +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; - skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL); - if (!skb) - return NULL; + if (!info->msg) + return false; - hdr = virtio_vsock_hdr(skb); - hdr->type = cpu_to_le16(info->type); - hdr->op = cpu_to_le16(info->op); - hdr->src_cid = cpu_to_le64(src_cid); - hdr->dst_cid = cpu_to_le64(dst_cid); - hdr->src_port = cpu_to_le32(src_port); - hdr->dst_port = cpu_to_le32(dst_port); - hdr->flags = cpu_to_le32(info->flags); - hdr->len = cpu_to_le32(len); + if (!(info->flags & MSG_ZEROCOPY) && !info->msg->msg_ubuf) + return false; - if (info->msg && len > 0) { - payload = skb_put(skb, len); - err = memcpy_from_msg(payload, info->msg, len); - if (err) - goto out; + iov_iter = &info->msg->msg_iter; + + if (iter_is_ubuf(iov_iter)) { + if (offset_in_page(iov_iter->ubuf)) + return false; + + 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; + + 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; - if (msg_data_left(info->msg) == 0 && - info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { - hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM); + /* 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; - if (info->msg->msg_flags & MSG_EOR) - hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR); + 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); } - if (info->reply) - virtio_vsock_skb_set_reply(skb); + /* 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); - trace_virtio_transport_alloc_pkt(src_cid, src_port, - dst_cid, dst_port, - len, - info->type, - info->op, - info->flags); + return true; +} - 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; +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; } - return skb; + skb_zcopy_init(skb, uarg); -out: - kfree_skb(skb); - return NULL; + 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; + + 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); + hdr->op = cpu_to_le16(info->op); + hdr->src_cid = cpu_to_le64(src_cid); + hdr->dst_cid = cpu_to_le64(dst_cid); + hdr->src_port = cpu_to_le32(src_port); + hdr->dst_port = cpu_to_le32(dst_port); + hdr->flags = cpu_to_le32(info->flags); + hdr->len = cpu_to_le32(len); } static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb, @@ -214,6 +302,75 @@ 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); + + if (info->msg && payload_len > 0) { + int err; + + if (zcopy) { + struct sock *sk = sk_vsock(vsk); + + err = __zerocopy_sg_from_iter(info->msg, sk, 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->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); + + 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; +} + /* This function can only be used on connecting/connected sockets, * since a socket assigned to a transport is required. * @@ -226,6 +383,8 @@ 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; @@ -235,6 +394,9 @@ 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) { @@ -254,22 +416,40 @@ 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) { + 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 +1064,7 @@ 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 +1116,11 @@ 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;