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Date: Thu, 22 Jun 2023 16:51:41 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Arseniy Krasnov <oxffffaa@...il.com>
Cc: Bobby Eshleman <bobby.eshleman@...edance.com>,
Stefan Hajnoczi <stefanha@...hat.com>, "Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
Bryan Tan <bryantan@...are.com>, Vishnu Dasa <vdasa@...are.com>,
VMware PV-Drivers Reviewers <pv-drivers@...are.com>, Dan Carpenter <dan.carpenter@...aro.org>,
Simon Horman <simon.horman@...igine.com>, kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [PATCH RFC net-next v4 1/8] vsock/dgram: generalize recvmsg and
drop transport->dgram_dequeue
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 <bobby.eshleman@...edance.com>
>> ---
>> 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)
>> + 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,
>>
>
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