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[54.67.115.33]) by smtp.gmail.com with ESMTPSA id s15-20020a62e70f000000b0066884d4efdbsm5156831pfh.12.2023.06.22.16.34.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jun 2023 16:34:30 -0700 (PDT) Date: Thu, 22 Jun 2023 23:34:29 +0000 From: Bobby Eshleman To: Arseniy Krasnov Cc: Stefano Garzarella , Bobby Eshleman , Stefan Hajnoczi , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Bryan Tan , Vishnu Dasa , VMware PV-Drivers Reviewers , Dan Carpenter , Simon Horman , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH RFC net-next v4 1/8] vsock/dgram: generalize recvmsg and drop transport->dgram_dequeue Message-ID: References: <20230413-b4-vsock-dgram-v4-0-0cebbb2ae899@bytedance.com> <20230413-b4-vsock-dgram-v4-1-0cebbb2ae899@bytedance.com> <3eb6216b-a3d2-e1ef-270c-8a0032a4a8a5@gmail.com> <63ko2n5fwjdefot6rzcxdftfh6pilg6vmqn66v4ue5dgf4oz53@tntmdijw4ghr> <2a0c29d5-d696-ac24-2a4a-1d691eef8daf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2a0c29d5-d696-ac24-2a4a-1d691eef8daf@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Thu, Jun 22, 2023 at 10:23:26PM +0300, Arseniy Krasnov wrote: > > > On 22.06.2023 17:51, Stefano Garzarella wrote: > > On Sun, Jun 11, 2023 at 11:43:15PM +0300, Arseniy Krasnov wrote: > >> Hello Bobby! Thanks for this patchset! Small comment below: > >> > >> On 10.06.2023 03:58, Bobby Eshleman wrote: > >>> This commit drops the transport->dgram_dequeue callback and makes > >>> vsock_dgram_recvmsg() generic. It also adds additional transport > >>> callbacks for use by the generic vsock_dgram_recvmsg(), such as for > >>> parsing skbs for CID/port which vary in format per transport. > >>> > >>> Signed-off-by: Bobby Eshleman > >>> --- > >>>  drivers/vhost/vsock.c                   |  4 +- > >>>  include/linux/virtio_vsock.h            |  3 ++ > >>>  include/net/af_vsock.h                  | 13 ++++++- > >>>  net/vmw_vsock/af_vsock.c                | 51 ++++++++++++++++++++++++- > >>>  net/vmw_vsock/hyperv_transport.c        | 17 +++++++-- > >>>  net/vmw_vsock/virtio_transport.c        |  4 +- > >>>  net/vmw_vsock/virtio_transport_common.c | 18 +++++++++ > >>>  net/vmw_vsock/vmci_transport.c          | 68 +++++++++++++-------------------- > >>>  net/vmw_vsock/vsock_loopback.c          |  4 +- > >>>  9 files changed, 132 insertions(+), 50 deletions(-) > >>> > >>> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c > >>> index 6578db78f0ae..c8201c070b4b 100644 > >>> --- a/drivers/vhost/vsock.c > >>> +++ b/drivers/vhost/vsock.c > >>> @@ -410,9 +410,11 @@ static struct virtio_transport vhost_transport = { > >>>          .cancel_pkt               = vhost_transport_cancel_pkt, > >>> > >>>          .dgram_enqueue            = virtio_transport_dgram_enqueue, > >>> -        .dgram_dequeue            = virtio_transport_dgram_dequeue, > >>>          .dgram_bind               = virtio_transport_dgram_bind, > >>>          .dgram_allow              = virtio_transport_dgram_allow, > >>> +        .dgram_get_cid          = virtio_transport_dgram_get_cid, > >>> +        .dgram_get_port          = virtio_transport_dgram_get_port, > >>> +        .dgram_get_length      = virtio_transport_dgram_get_length, > >>> > >>>          .stream_enqueue           = virtio_transport_stream_enqueue, > >>>          .stream_dequeue           = virtio_transport_stream_dequeue, > >>> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h > >>> index c58453699ee9..23521a318cf0 100644 > >>> --- a/include/linux/virtio_vsock.h > >>> +++ b/include/linux/virtio_vsock.h > >>> @@ -219,6 +219,9 @@ bool virtio_transport_stream_allow(u32 cid, u32 port); > >>>  int virtio_transport_dgram_bind(struct vsock_sock *vsk, > >>>                  struct sockaddr_vm *addr); > >>>  bool virtio_transport_dgram_allow(u32 cid, u32 port); > >>> +int virtio_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid); > >>> +int virtio_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port); > >>> +int virtio_transport_dgram_get_length(struct sk_buff *skb, size_t *len); > >>> > >>>  int virtio_transport_connect(struct vsock_sock *vsk); > >>> > >>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h > >>> index 0e7504a42925..7bedb9ee7e3e 100644 > >>> --- a/include/net/af_vsock.h > >>> +++ b/include/net/af_vsock.h > >>> @@ -120,11 +120,20 @@ struct vsock_transport { > >>> > >>>      /* DGRAM. */ > >>>      int (*dgram_bind)(struct vsock_sock *, struct sockaddr_vm *); > >>> -    int (*dgram_dequeue)(struct vsock_sock *vsk, struct msghdr *msg, > >>> -                 size_t len, int flags); > >>>      int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *, > >>>                   struct msghdr *, size_t len); > >>>      bool (*dgram_allow)(u32 cid, u32 port); > >>> +    int (*dgram_get_cid)(struct sk_buff *skb, unsigned int *cid); > >>> +    int (*dgram_get_port)(struct sk_buff *skb, unsigned int *port); > >>> +    int (*dgram_get_length)(struct sk_buff *skb, size_t *length); > >>> + > >>> +    /* The number of bytes into the buffer at which the payload starts, as > >>> +     * first seen by the receiving socket layer. For example, if the > >>> +     * transport presets the skb pointers using skb_pull(sizeof(header)) > >>> +     * than this would be zero, otherwise it would be the size of the > >>> +     * header. > >>> +     */ > >>> +    const size_t dgram_payload_offset; > >>> > >>>      /* STREAM. */ > >>>      /* TODO: stream_bind() */ > >>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > >>> index efb8a0937a13..ffb4dd8b6ea7 100644 > >>> --- a/net/vmw_vsock/af_vsock.c > >>> +++ b/net/vmw_vsock/af_vsock.c > >>> @@ -1271,11 +1271,15 @@ static int vsock_dgram_connect(struct socket *sock, > >>>  int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg, > >>>              size_t len, int flags) > >>>  { > >>> +    const struct vsock_transport *transport; > >>>  #ifdef CONFIG_BPF_SYSCALL > >>>      const struct proto *prot; > >>>  #endif > >>>      struct vsock_sock *vsk; > >>> +    struct sk_buff *skb; > >>> +    size_t payload_len; > >>>      struct sock *sk; > >>> +    int err; > >>> > >>>      sk = sock->sk; > >>>      vsk = vsock_sk(sk); > >>> @@ -1286,7 +1290,52 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg, > >>>          return prot->recvmsg(sk, msg, len, flags, NULL); > >>>  #endif > >>> > >>> -    return vsk->transport->dgram_dequeue(vsk, msg, len, flags); > >>> +    if (flags & MSG_OOB || flags & MSG_ERRQUEUE) > >>> +        return -EOPNOTSUPP; > >>> + > >>> +    transport = vsk->transport; > >>> + > >>> +    /* Retrieve the head sk_buff from the socket's receive queue. */ > >>> +    err = 0; > >>> +    skb = skb_recv_datagram(sk_vsock(vsk), flags, &err); > >>> +    if (!skb) > >>> +        return err; > >>> + > >>> +    err = transport->dgram_get_length(skb, &payload_len); > > > > What about ssize_t return value here? > > > > Or maybe a single callback that return both length and offset? > > > > .dgram_get_payload_info(skb, &payload_len, &payload_off) > > Just architectural question: > > May be we can avoid this callback for length? IIUC concept of skbuff is that > current level of network stack already have pointer to its data 'skb->data' and > length of the payload 'skb->len' (both are set by previous stack handler - transport in > this case), so here we can use just 'skb->len' and thats all. There is no need to ask > lower level of network stack for length of payload? I see that VMCI stores metadata > with payload in 'data' buffer, but may be it is more correctly to do 'skb_pull()' > in vmci before inserting skbuff to sockets queue? In this case field with dgram payload > offset could be removed from transport. > > Thanks, Arseniy > I agree, I think introducing the skb_pull() to vmci would honestly be best. I don't think it should break anything based on my reading of the code if it is called just prior to sk_receive_skb(). Thanks, Bobby > > > >>> +    if (err) > >>> +        goto out; > >>> + > >>> +    if (payload_len > len) { > >>> +        payload_len = len; > >>> +        msg->msg_flags |= MSG_TRUNC; > >>> +    } > >>> + > >>> +    /* Place the datagram payload in the user's iovec. */ > >>> +    err = skb_copy_datagram_msg(skb, transport->dgram_payload_offset, msg, payload_len); > >>> +    if (err) > >>> +        goto out; > >>> + > >>> +    if (msg->msg_name) { > >>> +        /* Provide the address of the sender. */ > >>> +        DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name); > >>> +        unsigned int cid, port; > >>> + > >>> +        err = transport->dgram_get_cid(skb, &cid); > >>> +        if (err) > >>> +            goto out; > >>> + > >>> +        err = transport->dgram_get_port(skb, &port); > >>> +        if (err) > >>> +            goto out; > >> > >> Maybe we can merge 'dgram_get_cid' and 'dgram_get_port' to a single callback? Because I see that this is > >> the only place where both are used (correct me if i'm wrong) and logically both operates with addresses: > >> CID and port. E.g. something like that: dgram_get_cid_n_port(). > > > > What about .dgram_addr_init(struct sk_buff *skb, struct sockaddr_vm *addr) > > and the transport can set cid and port? > > > >> > >> Moreover, I'm not sure, but is it good "tradeoff" here: remove transport specific callback for dgram receive > >> where we already have 'msghdr' with both data buffer and buffer for 'sockaddr_vm' and instead of it add new > >> several fields (callbacks) to transports like dgram_get_cid(), dgram_get_port()? I agree, that in each transport > >> specific callback we will have same copying logic by calling 'skb_copy_datagram_msg()' and filling address > >> by using 'vsock_addr_init()', but in this case we don't need to update transports too much. For example HyperV > >> still unchanged as it does not support SOCK_DGRAM. For VMCI You just need to add 'vsock_addr_init()' logic > >> to it's dgram dequeue callback. > >> > >> What do You think? > > > > Honestly, I'd rather avoid duplicate code than reduce changes in > > transports that don't support dgram. > > > > One thing I do agree on though is minimizing the number of callbacks > > to call to reduce the number of indirection (more performance?). > > > > Thanks, > > Stefano > > > >> > >> Thanks, Arseniy > >> > >>> + > >>> +        vsock_addr_init(vm_addr, cid, port); > >>> +        msg->msg_namelen = sizeof(*vm_addr); > >>> +    } > >>> +    err = payload_len; > >>> + > >>> +out: > >>> +    skb_free_datagram(&vsk->sk, skb); > >>> +    return err; > >>>  } > >>>  EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg); > >>> > >>> diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c > >>> index 7cb1a9d2cdb4..ff6e87e25fa0 100644 > >>> --- a/net/vmw_vsock/hyperv_transport.c > >>> +++ b/net/vmw_vsock/hyperv_transport.c > >>> @@ -556,8 +556,17 @@ static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr) > >>>      return -EOPNOTSUPP; > >>>  } > >>> > >>> -static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg, > >>> -                 size_t len, int flags) > >>> +static int hvs_dgram_get_cid(struct sk_buff *skb, unsigned int *cid) > >>> +{ > >>> +    return -EOPNOTSUPP; > >>> +} > >>> + > >>> +static int hvs_dgram_get_port(struct sk_buff *skb, unsigned int *port) > >>> +{ > >>> +    return -EOPNOTSUPP; > >>> +} > >>> + > >>> +static int hvs_dgram_get_length(struct sk_buff *skb, size_t *len) > >>>  { > >>>      return -EOPNOTSUPP; > >>>  } > >>> @@ -833,7 +842,9 @@ static struct vsock_transport hvs_transport = { > >>>      .shutdown                 = hvs_shutdown, > >>> > >>>      .dgram_bind               = hvs_dgram_bind, > >>> -    .dgram_dequeue            = hvs_dgram_dequeue, > >>> +    .dgram_get_cid          = hvs_dgram_get_cid, > >>> +    .dgram_get_port          = hvs_dgram_get_port, > >>> +    .dgram_get_length      = hvs_dgram_get_length, > >>>      .dgram_enqueue            = hvs_dgram_enqueue, > >>>      .dgram_allow              = hvs_dgram_allow, > >>> > >>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > >>> index e95df847176b..5763cdf13804 100644 > >>> --- a/net/vmw_vsock/virtio_transport.c > >>> +++ b/net/vmw_vsock/virtio_transport.c > >>> @@ -429,9 +429,11 @@ static struct virtio_transport virtio_transport = { > >>>          .cancel_pkt               = virtio_transport_cancel_pkt, > >>> > >>>          .dgram_bind               = virtio_transport_dgram_bind, > >>> -        .dgram_dequeue            = virtio_transport_dgram_dequeue, > >>>          .dgram_enqueue            = virtio_transport_dgram_enqueue, > >>>          .dgram_allow              = virtio_transport_dgram_allow, > >>> +        .dgram_get_cid          = virtio_transport_dgram_get_cid, > >>> +        .dgram_get_port          = virtio_transport_dgram_get_port, > >>> +        .dgram_get_length      = virtio_transport_dgram_get_length, > >>> > >>>          .stream_dequeue           = virtio_transport_stream_dequeue, > >>>          .stream_enqueue           = virtio_transport_stream_enqueue, > >>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > >>> index b769fc258931..e6903c719964 100644 > >>> --- a/net/vmw_vsock/virtio_transport_common.c > >>> +++ b/net/vmw_vsock/virtio_transport_common.c > >>> @@ -797,6 +797,24 @@ int virtio_transport_dgram_bind(struct vsock_sock *vsk, > >>>  } > >>>  EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind); > >>> > >>> +int virtio_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid) > >>> +{ > >>> +    return -EOPNOTSUPP; > >>> +} > >>> +EXPORT_SYMBOL_GPL(virtio_transport_dgram_get_cid); > >>> + > >>> +int virtio_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port) > >>> +{ > >>> +    return -EOPNOTSUPP; > >>> +} > >>> +EXPORT_SYMBOL_GPL(virtio_transport_dgram_get_port); > >>> + > >>> +int virtio_transport_dgram_get_length(struct sk_buff *skb, size_t *len) > >>> +{ > >>> +    return -EOPNOTSUPP; > >>> +} > >>> +EXPORT_SYMBOL_GPL(virtio_transport_dgram_get_length); > >>> + > >>>  bool virtio_transport_dgram_allow(u32 cid, u32 port) > >>>  { > >>>      return false; > >>> diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c > >>> index b370070194fa..bbc63826bf48 100644 > >>> --- a/net/vmw_vsock/vmci_transport.c > >>> +++ b/net/vmw_vsock/vmci_transport.c > >>> @@ -1731,57 +1731,40 @@ static int vmci_transport_dgram_enqueue( > >>>      return err - sizeof(*dg); > >>>  } > >>> > >>> -static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk, > >>> -                    struct msghdr *msg, size_t len, > >>> -                    int flags) > >>> +static int vmci_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid) > >>>  { > >>> -    int err; > >>>      struct vmci_datagram *dg; > >>> -    size_t payload_len; > >>> -    struct sk_buff *skb; > >>> > >>> -    if (flags & MSG_OOB || flags & MSG_ERRQUEUE) > >>> -        return -EOPNOTSUPP; > >>> +    dg = (struct vmci_datagram *)skb->data; > >>> +    if (!dg) > >>> +        return -EINVAL; > >>> > >>> -    /* Retrieve the head sk_buff from the socket's receive queue. */ > >>> -    err = 0; > >>> -    skb = skb_recv_datagram(&vsk->sk, flags, &err); > >>> -    if (!skb) > >>> -        return err; > >>> +    *cid = dg->src.context; > >>> +    return 0; > >>> +} > >>> + > >>> +static int vmci_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port) > >>> +{ > >>> +    struct vmci_datagram *dg; > >>> > >>>      dg = (struct vmci_datagram *)skb->data; > >>>      if (!dg) > >>> -        /* err is 0, meaning we read zero bytes. */ > >>> -        goto out; > >>> - > >>> -    payload_len = dg->payload_size; > >>> -    /* Ensure the sk_buff matches the payload size claimed in the packet. */ > >>> -    if (payload_len != skb->len - sizeof(*dg)) { > >>> -        err = -EINVAL; > >>> -        goto out; > >>> -    } > >>> +        return -EINVAL; > >>> > >>> -    if (payload_len > len) { > >>> -        payload_len = len; > >>> -        msg->msg_flags |= MSG_TRUNC; > >>> -    } > >>> +    *port = dg->src.resource; > >>> +    return 0; > >>> +} > >>> > >>> -    /* Place the datagram payload in the user's iovec. */ > >>> -    err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len); > >>> -    if (err) > >>> -        goto out; > >>> +static int vmci_transport_dgram_get_length(struct sk_buff *skb, size_t *len) > >>> +{ > >>> +    struct vmci_datagram *dg; > >>> > >>> -    if (msg->msg_name) { > >>> -        /* Provide the address of the sender. */ > >>> -        DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name); > >>> -        vsock_addr_init(vm_addr, dg->src.context, dg->src.resource); > >>> -        msg->msg_namelen = sizeof(*vm_addr); > >>> -    } > >>> -    err = payload_len; > >>> +    dg = (struct vmci_datagram *)skb->data; > >>> +    if (!dg) > >>> +        return -EINVAL; > >>> > >>> -out: > >>> -    skb_free_datagram(&vsk->sk, skb); > >>> -    return err; > >>> +    *len = dg->payload_size; > >>> +    return 0; > >>>  } > >>> > >>>  static bool vmci_transport_dgram_allow(u32 cid, u32 port) > >>> @@ -2040,9 +2023,12 @@ static struct vsock_transport vmci_transport = { > >>>      .release = vmci_transport_release, > >>>      .connect = vmci_transport_connect, > >>>      .dgram_bind = vmci_transport_dgram_bind, > >>> -    .dgram_dequeue = vmci_transport_dgram_dequeue, > >>>      .dgram_enqueue = vmci_transport_dgram_enqueue, > >>>      .dgram_allow = vmci_transport_dgram_allow, > >>> +    .dgram_get_cid = vmci_transport_dgram_get_cid, > >>> +    .dgram_get_port = vmci_transport_dgram_get_port, > >>> +    .dgram_get_length = vmci_transport_dgram_get_length, > >>> +    .dgram_payload_offset = sizeof(struct vmci_datagram), > >>>      .stream_dequeue = vmci_transport_stream_dequeue, > >>>      .stream_enqueue = vmci_transport_stream_enqueue, > >>>      .stream_has_data = vmci_transport_stream_has_data, > >>> diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c > >>> index 5c6360df1f31..2f3cabc79ee5 100644 > >>> --- a/net/vmw_vsock/vsock_loopback.c > >>> +++ b/net/vmw_vsock/vsock_loopback.c > >>> @@ -62,9 +62,11 @@ static struct virtio_transport loopback_transport = { > >>>          .cancel_pkt               = vsock_loopback_cancel_pkt, > >>> > >>>          .dgram_bind               = virtio_transport_dgram_bind, > >>> -        .dgram_dequeue            = virtio_transport_dgram_dequeue, > >>>          .dgram_enqueue            = virtio_transport_dgram_enqueue, > >>>          .dgram_allow              = virtio_transport_dgram_allow, > >>> +        .dgram_get_cid          = virtio_transport_dgram_get_cid, > >>> +        .dgram_get_port          = virtio_transport_dgram_get_port, > >>> +        .dgram_get_length      = virtio_transport_dgram_get_length, > >>> > >>>          .stream_dequeue           = virtio_transport_stream_dequeue, > >>>          .stream_enqueue           = virtio_transport_stream_enqueue, > >>> > >> > >