Stefano Garzarella
2023-Jul-25 12:28 UTC
[PATCH net-next v3 4/4] vsock/virtio: MSG_ZEROCOPY flag support
On Tue, Jul 25, 2023 at 12:16:11PM +0300, Arseniy Krasnov wrote:> > >On 25.07.2023 11:46, Arseniy Krasnov wrote: >> >> >> On 25.07.2023 11:43, Stefano Garzarella wrote: >>> On Fri, Jul 21, 2023 at 08:09:03AM +0300, Arseniy Krasnov wrote: >>>> >>>> >>>> On 21.07.2023 00:42, Arseniy Krasnov wrote: >>>>> This adds handling of MSG_ZEROCOPY flag on transmission path: if this >>>>> flag is set and zerocopy transmission is possible (enabled in socket >>>>> options and transport allows zerocopy), 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()'. Second thing that >>>>> this patch does is replace type of skb owning: instead of calling >>>>> 'skb_set_owner_sk_safe()' it calls 'skb_set_owner_w()'. Reason of this >>>>> change is that '__zerocopy_sg_from_iter()' increments 'sk_wmem_alloc' >>>>> of socket, so to decrease this field correctly proper skb destructor is >>>>> needed: 'sock_wfree()'. This destructor is set by 'skb_set_owner_w()'. >>>>> >>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov at sberdevices.ru> >>>>> --- >>>>> ?Changelog: >>>>> ?v5(big patchset) -> v1: >>>>> ? * Refactorings of 'if' conditions. >>>>> ? * Remove extra blank line. >>>>> ? * Remove 'frag_off' field unneeded init. >>>>> ? * Add function 'virtio_transport_fill_skb()' which fills both linear >>>>> ??? and non-linear skb with provided data. >>>>> ?v1 -> v2: >>>>> ? * Use original order of last four arguments in 'virtio_transport_alloc_skb()'. >>>>> ?v2 -> v3: >>>>> ? * Add new transport callback: 'msgzerocopy_check_iov'. It checks that >>>>> ??? provided 'iov_iter' with data could be sent in a zerocopy mode. >>>>> ??? If this callback is not set in transport - transport allows to send >>>>> ??? any 'iov_iter' in zerocopy mode. Otherwise - if callback returns 'true' >>>>> ??? then zerocopy is allowed. Reason of this callback is that in case of >>>>> ??? G2H transmission we insert whole skb to the tx virtio queue and such >>>>> ??? skb must fit to the size of the virtio queue to be sent in a single >>>>> ??? iteration (may be tx logic in 'virtio_transport.c' could be reworked >>>>> ??? as in vhost to support partial send of current skb). This callback >>>>> ??? will be enabled only for G2H path. For details pls see comment >>>>> ??? 'Check that tx queue...' below. >>>>> >>>>> ?include/net/af_vsock.h????????????????? |?? 3 + >>>>> ?net/vmw_vsock/virtio_transport.c??????? |? 39 ++++ >>>>> ?net/vmw_vsock/virtio_transport_common.c | 257 ++++++++++++++++++------ >>>>> ?3 files changed, 241 insertions(+), 58 deletions(-) >>>>> >>>>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h >>>>> index 0e7504a42925..a6b346eeeb8e 100644 >>>>> --- a/include/net/af_vsock.h >>>>> +++ b/include/net/af_vsock.h >>>>> @@ -177,6 +177,9 @@ struct vsock_transport { >>>>> >>>>> ???? /* Read a single skb */ >>>>> ???? int (*read_skb)(struct vsock_sock *, skb_read_actor_t); >>>>> + >>>>> +??? /* Zero-copy. */ >>>>> +??? bool (*msgzerocopy_check_iov)(const struct iov_iter *); >>>>> ?}; >>>>> >>>>> ?/**** CORE ****/ >>>>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >>>>> index 7bbcc8093e51..23cb8ed638c4 100644 >>>>> --- a/net/vmw_vsock/virtio_transport.c >>>>> +++ b/net/vmw_vsock/virtio_transport.c >>>>> @@ -442,6 +442,43 @@ static void virtio_vsock_rx_done(struct virtqueue *vq) >>>>> ???? queue_work(virtio_vsock_workqueue, &vsock->rx_work); >>>>> ?} >>>>> >>>>> +static bool virtio_transport_msgzerocopy_check_iov(const struct >>>>> iov_iter *iov) >>>>> +{ >>>>> +??? struct virtio_vsock *vsock; >>>>> +??? bool res = false; >>>>> + >>>>> +??? rcu_read_lock(); >>>>> + >>>>> +??? vsock = rcu_dereference(the_virtio_vsock); >>>>> +??? if (vsock) {Just noted, what about the following to reduce the indentation? if (!vsock) { goto out; } ... ... out: rcu_read_unlock(); return res;>>>>> +??????? struct virtqueue *vq; >>>>> +??????? int iov_pages; >>>>> + >>>>> +??????? vq = vsock->vqs[VSOCK_VQ_TX]; >>>>> + >>>>> +??????? iov_pages = round_up(iov->count, PAGE_SIZE) / PAGE_SIZE; >>>>> + >>>>> +??????? /* Check that tx queue is large enough to keep whole >>>>> +???????? * data to send. This is needed, because when there is >>>>> +???????? * not enough free space in the queue, current skb to >>>>> +???????? * send will be reinserted to the head of tx list of >>>>> +???????? * the socket to retry transmission later, so if skb >>>>> +???????? * is bigger than whole queue, it will be reinserted >>>>> +???????? * again and again, thus blocking other skbs to be sent. >>>>> +???????? * Each page of the user provided buffer will be added >>>>> +???????? * as a single buffer to the tx virtqueue, so compare >>>>> +???????? * number of pages against maximum capacity of the queue. >>>>> +???????? * +1 means buffer for the packet header. >>>>> +???????? */ >>>>> +??????? if (iov_pages + 1 <= vq->num_max) >>>> >>>> I think this check is actual only for case one we don't have indirect buffer feature. >>>> With indirect mode whole data to send will be packed into one indirect buffer. >>> >>> I think so. >>> So, should we check also that here? >>> >>>> >>>> Thanks, Arseniy >>>> >>>>> +??????????? res = true; >>>>> +??? } >>>>> + >>>>> +??? rcu_read_unlock(); >>>>> + >>>>> +??? return res; >>>>> +} >>>>> + >>>>> ?static bool virtio_transport_seqpacket_allow(u32 remote_cid); >>>>> >>>>> ?static struct virtio_transport virtio_transport = { >>>>> @@ -475,6 +512,8 @@ static struct virtio_transport virtio_transport = { >>>>> ???????? .seqpacket_allow????????? = virtio_transport_seqpacket_allow, >>>>> ???????? .seqpacket_has_data?????? = virtio_transport_seqpacket_has_data, >>>>> >>>>> +??????? .msgzerocopy_check_iov????? = virtio_transport_msgzerocopy_check_iov, >>>>> + >>>>> ???????? .notify_poll_in?????????? = virtio_transport_notify_poll_in, >>>>> ???????? .notify_poll_out????????? = virtio_transport_notify_poll_out, >>>>> ???????? .notify_recv_init???????? = virtio_transport_notify_recv_init, >>>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>>>> index 26a4d10da205..e4e3d541aff4 100644 >>>>> --- a/net/vmw_vsock/virtio_transport_common.c >>>>> +++ b/net/vmw_vsock/virtio_transport_common.c >>>>> @@ -37,73 +37,122 @@ 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) >>>>> +{ >>>>> +??? const struct vsock_transport *t; >>>>> +??? struct iov_iter *iov_iter; >>>>> >>>>> -??? 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); >>>>> +??? iov_iter = &info->msg->msg_iter; >>>>> >>>>> -??? if (info->msg && len > 0) { >>>>> -??????? payload = skb_put(skb, len); >>>>> -??????? err = memcpy_from_msg(payload, info->msg, len); >>>>> -??????? if (err) >>>>> -??????????? goto out; >>>>> +??? t = vsock_core_get_transport(info->vsk); >>>>> >>>>> -??????? if (msg_data_left(info->msg) == 0 && >>>>> -??????????? info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >>>>> -??????????? hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM); >>>>> +??? if (t->msgzerocopy_check_iov && >>>>> +??????? !t->msgzerocopy_check_iov(iov_iter)) >>>>> +??????? return false; >>> >>> I'd avoid adding a new transport callback used only internally in virtio >>> transports. >> >> Ok, I see. >> >>> >>> Usually the transport callbacks are used in af_vsock.c, if we need a >>> callback just for virtio transports, maybe better to add it in struct >>> virtio_vsock_pkt_info or struct virtio_vsock_sock. > >Hm, may be I just need to move this callback from 'struct vsock_transport' to parent 'struct virtio_transport', >after 'send_pkt' callback. In this case: >1) AF_VSOCK part is not touched. >2) This callback stays in 'virtio_transport.c' and is set also in this file. > vhost and loopback are unchanged - only 'send_pkt' still enabled in both > files for these two transports.Yep, this could also work! Stefano> >Thanks, Arseniy > >>> >>> Maybe better the last one so we don't have to allocate pointer space >>> for each packet and you should reach it via info. >> >> Ok, thanks, I'll try this way >> >> Thanks, Arseniy >> >>> >>> Thanks, >>> Stefano >>> >>>>> >>>>> -??????????? if (info->msg->msg_flags & MSG_EOR) >>>>> -??????????????? hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR); >>>>> -??????? } >>>>> +??? /* 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; >>>>> ???? } >>>>> >>>>> -??? if (info->reply) >>>>> -??????? virtio_vsock_skb_set_reply(skb); >>>>> +??? skb_zcopy_init(skb, uarg); >>>>> >>>>> -??? trace_virtio_transport_alloc_pkt(src_cid, src_port, >>>>> -???????????????????? dst_cid, dst_port, >>>>> -???????????????????? len, >>>>> -???????????????????? info->type, >>>>> -???????????????????? info->op, >>>>> -???????????????????? info->flags); >>>>> +??? return 0; >>>>> +} >>>>> >>>>> -??? 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_fill_skb(struct sk_buff *skb, >>>>> +???????????????????? struct virtio_vsock_pkt_info *info, >>>>> +???????????????????? size_t len, >>>>> +???????????????????? bool zcopy) >>>>> +{ >>>>> +??? if (zcopy) { >>>>> +??????? return __zerocopy_sg_from_iter(info->msg, NULL, skb, >>>>> +????????????????????????? &info->msg->msg_iter, >>>>> +????????????????????????? len); >>>>> +??? } else { >>>>> +??????? 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; >>>>> + >>>>> +??????? return 0; >>>>> ???? } >>>>> +} >>>>> >>>>> -??? return skb; >>>>> +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; >>>>> >>>>> -out: >>>>> -??? kfree_skb(skb); >>>>> -??? return NULL; >>>>> +??? 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(const struct sk_buff *skb, >>>>> @@ -214,6 +263,70 @@ static u16 virtio_transport_get_type(struct sock *sk) >>>>> ???????? return VIRTIO_VSOCK_TYPE_SEQPACKET; >>>>> ?} >>>>> >>>>> +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 src_cid, >>>>> +????????????????????????? u32 src_port, >>>>> +????????????????????????? u32 dst_cid, >>>>> +????????????????????????? u32 dst_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; >>>>> + >>>>> +??????? err = virtio_transport_fill_skb(skb, info, payload_len, zcopy); >>>>> +??????? if (err) >>>>> +??????????? goto out; >>>>> + >>>>> +??????? if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) { >>>>> +??????????? struct virtio_vsock_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. >>>>> ? * >>>>> @@ -222,10 +335,12 @@ static u16 virtio_transport_get_type(struct sock *sk) >>>>> ?static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >>>>> ?????????????????????? struct virtio_vsock_pkt_info *info) >>>>> ?{ >>>>> +??? u32 max_skb_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE; >>>>> ???? u32 src_cid, src_port, dst_cid, dst_port; >>>>> ???? const struct virtio_transport *t_ops; >>>>> ???? struct virtio_vsock_sock *vvs; >>>>> ???? u32 pkt_len = info->pkt_len; >>>>> +??? bool can_zcopy = false; >>>>> ???? u32 rest_len; >>>>> ???? int ret; >>>>> >>>>> @@ -254,15 +369,30 @@ 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 (info->msg) { >>>>> +??????? /* 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->msg->msg_flags &= ~MSG_ZEROCOPY; >>>>> + >>>>> +??????? if (info->msg->msg_flags & MSG_ZEROCOPY) >>>>> +??????????? can_zcopy = virtio_transport_can_zcopy(info, pkt_len); >>>>> + >>>>> +??????? if (can_zcopy) >>>>> +??????????? max_skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, >>>>> +??????????????????????? (MAX_SKB_FRAGS * PAGE_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_len, rest_len); >>>>> >>>>> -??????? skb = virtio_transport_alloc_skb(info, skb_len, >>>>> +??????? skb = virtio_transport_alloc_skb(vsk, info, skb_len, can_zcopy, >>>>> ????????????????????????? src_cid, src_port, >>>>> ????????????????????????? dst_cid, dst_port); >>>>> ???????? if (!skb) { >>>>> @@ -270,6 +400,17 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >>>>> ???????????? break; >>>>> ???????? } >>>>> >>>>> +??????? /* This is last skb to send this portion of data. */ >>>>> +??????? if (info->msg && info->msg->msg_flags & MSG_ZEROCOPY && >>>>> +??????????? skb_len == rest_len && 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); >>>>> @@ -934,7 +1075,7 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t, >>>>> ???? if (!t) >>>>> ???????? return -ENOTCONN; >>>>> >>>>> -??? reply = virtio_transport_alloc_skb(&info, 0, >>>>> +??? reply = virtio_transport_alloc_skb(NULL, &info, 0, false, >>>>> ??????????????????????? le64_to_cpu(hdr->dst_cid), >>>>> ??????????????????????? le32_to_cpu(hdr->dst_port), >>>>> ??????????????????????? le64_to_cpu(hdr->src_cid), >>>> >>> >
Michael S. Tsirkin
2023-Jul-25 12:39 UTC
[PATCH net-next v3 4/4] vsock/virtio: MSG_ZEROCOPY flag support
On Tue, Jul 25, 2023 at 02:28:02PM +0200, Stefano Garzarella wrote:> On Tue, Jul 25, 2023 at 12:16:11PM +0300, Arseniy Krasnov wrote: > > > > > > On 25.07.2023 11:46, Arseniy Krasnov wrote: > > > > > > > > > On 25.07.2023 11:43, Stefano Garzarella wrote: > > > > On Fri, Jul 21, 2023 at 08:09:03AM +0300, Arseniy Krasnov wrote: > > > > > > > > > > > > > > > On 21.07.2023 00:42, Arseniy Krasnov wrote: > > > > > > This adds handling of MSG_ZEROCOPY flag on transmission path: if this > > > > > > flag is set and zerocopy transmission is possible (enabled in socket > > > > > > options and transport allows zerocopy), 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()'. Second thing that > > > > > > this patch does is replace type of skb owning: instead of calling > > > > > > 'skb_set_owner_sk_safe()' it calls 'skb_set_owner_w()'. Reason of this > > > > > > change is that '__zerocopy_sg_from_iter()' increments 'sk_wmem_alloc' > > > > > > of socket, so to decrease this field correctly proper skb destructor is > > > > > > needed: 'sock_wfree()'. This destructor is set by 'skb_set_owner_w()'. > > > > > > > > > > > > Signed-off-by: Arseniy Krasnov <AVKrasnov at sberdevices.ru> > > > > > > --- > > > > > > ?Changelog: > > > > > > ?v5(big patchset) -> v1: > > > > > > ? * Refactorings of 'if' conditions. > > > > > > ? * Remove extra blank line. > > > > > > ? * Remove 'frag_off' field unneeded init. > > > > > > ? * Add function 'virtio_transport_fill_skb()' which fills both linear > > > > > > ??? and non-linear skb with provided data. > > > > > > ?v1 -> v2: > > > > > > ? * Use original order of last four arguments in 'virtio_transport_alloc_skb()'. > > > > > > ?v2 -> v3: > > > > > > ? * Add new transport callback: 'msgzerocopy_check_iov'. It checks that > > > > > > ??? provided 'iov_iter' with data could be sent in a zerocopy mode. > > > > > > ??? If this callback is not set in transport - transport allows to send > > > > > > ??? any 'iov_iter' in zerocopy mode. Otherwise - if callback returns 'true' > > > > > > ??? then zerocopy is allowed. Reason of this callback is that in case of > > > > > > ??? G2H transmission we insert whole skb to the tx virtio queue and such > > > > > > ??? skb must fit to the size of the virtio queue to be sent in a single > > > > > > ??? iteration (may be tx logic in 'virtio_transport.c' could be reworked > > > > > > ??? as in vhost to support partial send of current skb). This callback > > > > > > ??? will be enabled only for G2H path. For details pls see comment > > > > > > ??? 'Check that tx queue...' below. > > > > > > > > > > > > ?include/net/af_vsock.h????????????????? |?? 3 + > > > > > > ?net/vmw_vsock/virtio_transport.c??????? |? 39 ++++ > > > > > > ?net/vmw_vsock/virtio_transport_common.c | 257 ++++++++++++++++++------ > > > > > > ?3 files changed, 241 insertions(+), 58 deletions(-) > > > > > > > > > > > > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h > > > > > > index 0e7504a42925..a6b346eeeb8e 100644 > > > > > > --- a/include/net/af_vsock.h > > > > > > +++ b/include/net/af_vsock.h > > > > > > @@ -177,6 +177,9 @@ struct vsock_transport { > > > > > > > > > > > > ???? /* Read a single skb */ > > > > > > ???? int (*read_skb)(struct vsock_sock *, skb_read_actor_t); > > > > > > + > > > > > > +??? /* Zero-copy. */ > > > > > > +??? bool (*msgzerocopy_check_iov)(const struct iov_iter *); > > > > > > ?}; > > > > > > > > > > > > ?/**** CORE ****/ > > > > > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > > > > > > index 7bbcc8093e51..23cb8ed638c4 100644 > > > > > > --- a/net/vmw_vsock/virtio_transport.c > > > > > > +++ b/net/vmw_vsock/virtio_transport.c > > > > > > @@ -442,6 +442,43 @@ static void virtio_vsock_rx_done(struct virtqueue *vq) > > > > > > ???? queue_work(virtio_vsock_workqueue, &vsock->rx_work); > > > > > > ?} > > > > > > > > > > > > +static bool > > > > > > virtio_transport_msgzerocopy_check_iov(const struct > > > > > > iov_iter *iov) > > > > > > +{ > > > > > > +??? struct virtio_vsock *vsock; > > > > > > +??? bool res = false; > > > > > > + > > > > > > +??? rcu_read_lock(); > > > > > > + > > > > > > +??? vsock = rcu_dereference(the_virtio_vsock); > > > > > > +??? if (vsock) { > > Just noted, what about the following to reduce the indentation? > > if (!vsock) { > goto out; > }no {} pls> ... > ... > out: > rcu_read_unlock(); > return res;indentation is quite modest here. Not sure goto is worth it.