Date:   Fri, 11 Jun 2021 14:17:00 +0300
From:   Arseny Krasnov <arseny.krasnov@...persky.com>
To:     Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Andra Paraschiv <andraprs@...zon.com>,
        Norbert Slusarek <nslusarek@....net>,
        Colin Ian King <colin.king@...onical.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "oxffffaa@...il.com" <oxffffaa@...il.com>
Subject: Re: [PATCH v11 00/18] virtio/vsock: introduce SOCK_SEQPACKET support


On 11.06.2021 14:07, Arseny Krasnov wrote:
> 	This patchset implements support of SOCK_SEQPACKET for virtio
> transport.
> 	As SOCK_SEQPACKET guarantees to save record boundaries, so to
> do it, new bit for field 'flags' was added: SEQ_EOR. This bit is
> set to 1 in last RW packet of message.
> 	Now as  packets of one socket are not reordered neither on vsock
> nor on vhost transport layers, such bit allows to restore original
> message on receiver's side. If user's buffer is smaller than message
> length, when all out of size data is dropped.
> 	Maximum length of datagram is limited by 'peer_buf_alloc' value.
> 	Implementation also supports 'MSG_TRUNC' flags.
> 	Tests also implemented.
>
> 	Thanks to stsp2@...dex.ru for encouragements and initial design
> recommendations.
>
>  Arseny Krasnov (18):
>   af_vsock: update functions for connectible socket
>   af_vsock: separate wait data loop
>   af_vsock: separate receive data loop
>   af_vsock: implement SEQPACKET receive loop
>   af_vsock: implement send logic for SEQPACKET
>   af_vsock: rest of SEQPACKET support
>   af_vsock: update comments for stream sockets
>   virtio/vsock: set packet's type in virtio_transport_send_pkt_info()
>   virtio/vsock: simplify credit update function API
>   virtio/vsock: defines and constants for SEQPACKET
>   virtio/vsock: dequeue callback for SOCK_SEQPACKET
>   virtio/vsock: add SEQPACKET receive logic
>   virtio/vsock: rest of SOCK_SEQPACKET support
>   virtio/vsock: enable SEQPACKET for transport
>   vhost/vsock: enable SEQPACKET for transport
>   vsock/loopback: enable SEQPACKET for transport
>   vsock_test: add SOCK_SEQPACKET tests
>   virtio/vsock: update trace event for SEQPACKET
>
>  drivers/vhost/vsock.c                              |  56 ++-
>  include/linux/virtio_vsock.h                       |  10 +
>  include/net/af_vsock.h                             |   8 +
>  .../trace/events/vsock_virtio_transport_common.h   |   5 +-
>  include/uapi/linux/virtio_vsock.h                  |   9 +
>  net/vmw_vsock/af_vsock.c                           | 464 ++++++++++++------
>  net/vmw_vsock/virtio_transport.c                   |  26 ++
>  net/vmw_vsock/virtio_transport_common.c            | 179 +++++++-
>  net/vmw_vsock/vsock_loopback.c                     |  12 +
>  tools/testing/vsock/util.c                         |  32 +-
>  tools/testing/vsock/util.h                         |   3 +
>  tools/testing/vsock/vsock_test.c                   | 116 ++++++
>  12 files changed, 730 insertions(+), 190 deletions(-)
>
>  v10 -> v11:
>  General changelog:
>   - now data is copied to user's buffer only when
>     whole message is received.
>   - reader is woken up when EOR packet is received.
>   - if read syscall was interrupted by signal or
>     timeout, error is returned(not 0).
>
>  Per patch changelog:
>   see every patch after '---' line.
So here is new version for review with updates discussed earlier :)
>
>  v9 -> v10:
>  General changelog:
>  - patch for write serialization removed from patchset.
>  - commit messages rephrased
>
>  Per patch changelog:
>   see every patch after '---' line.
>
>  v8 -> v9:
>  General changelog:
>  - see per patch change log.
>
>  Per patch changelog:
>   see every patch after '---' line.
>
>  v7 -> v8:
>  General changelog:
>  - whole idea is simplified: channel now considered reliable,
>    so SEQ_BEGIN, SEQ_END, 'msg_len' and 'msg_id' were removed.
>    Only thing that is used to mark end of message is bit in
>    'flags' field of packet header: VIRTIO_VSOCK_SEQ_EOR. Packet
>    with such bit set to 1 means, that this is last packet of
>    message.
>
>  - POSIX MSG_EOR support is removed, as there is no exact
>    description how it works.
>
>  - all changes to 'include/uapi/linux/virtio_vsock.h' moved
>    to dedicated patch, as these changes linked with patch to
>    spec.
>
>  - patch 'virtio/vsock: SEQPACKET feature bit support' now merged
>    to 'virtio/vsock: setup SEQPACKET ops for transport'.
>
>  - patch 'vhost/vsock: SEQPACKET feature bit support' now merged
>    to 'vhost/vsock: setup SEQPACKET ops for transport'.
>
>  Per patch changelog:
>   see every patch after '---' line.
>
>  v6 -> v7:
>  General changelog:
>  - virtio transport callback for message length now removed
>    from transport. Length of record is returned by dequeue
>    callback.
>
>  - function which tries to get message length now returns 0
>    when rx queue is empty. Also length of current message in
>    progress is set to 0, when message processed or error
>    happens.
>
>  - patches for virtio feature bit moved after patches with
>    transport ops.
>
>  Per patch changelog:
>   see every patch after '---' line.
>
>  v5 -> v6:
>  General changelog:
>  - virtio transport specific callbacks which send SEQ_BEGIN or
>    SEQ_END now hidden inside virtio transport. Only enqueue,
>    dequeue and record length callbacks are provided by transport.
>
>  - virtio feature bit for SEQPACKET socket support introduced:
>    VIRTIO_VSOCK_F_SEQPACKET.
>
>  - 'msg_cnt' field in 'struct virtio_vsock_seq_hdr' renamed to
>    'msg_id' and used as id.
>
>  Per patch changelog:
>  - 'af_vsock: separate wait data loop':
>     1) Commit message updated.
>     2) 'prepare_to_wait()' moved inside while loop(thanks to
>       Jorgen Hansen).
>     Marked 'Reviewed-by' with 1), but as 2) I removed R-b.
>
>  - 'af_vsock: separate receive data loop': commit message
>     updated.
>     Marked 'Reviewed-by' with that fix.
>
>  - 'af_vsock: implement SEQPACKET receive loop': style fixes.
>
>  - 'af_vsock: rest of SEQPACKET support':
>     1) 'module_put()' added when transport callback check failed.
>     2) Now only 'seqpacket_allow()' callback called to check
>        support of SEQPACKET by transport.
>
>  - 'af_vsock: update comments for stream sockets': commit message
>     updated.
>     Marked 'Reviewed-by' with that fix.
>
>  - 'virtio/vsock: set packet's type in send':
>     1) Commit message updated.
>     2) Parameter 'type' from 'virtio_transport_send_credit_update()'
>        also removed in this patch instead of in next.
>
>  - 'virtio/vsock: dequeue callback for SOCK_SEQPACKET': SEQPACKET
>     related state wrapped to special struct.
>
>  - 'virtio/vsock: update trace event for SEQPACKET': format strings
>     now not broken by new lines.
>
>  v4 -> v5:
>  - patches reorganized:
>    1) Setting of packet's type in 'virtio_transport_send_pkt_info()'
>       is moved to separate patch.
>    2) Simplifying of 'virtio_transport_send_credit_update()' is
>       moved to separate patch and before main virtio/vsock patches.
>  - style problem fixed
>  - in 'af_vsock: separate receive data loop' extra 'release_sock()'
>    removed
>  - added trace event fields for SEQPACKET
>  - in 'af_vsock: separate wait data loop':
>    1) 'vsock_wait_data()' removed 'goto out;'
>    2) Comment for invalid data amount is changed.
>  - in 'af_vsock: rest of SEQPACKET support', 'new_transport' pointer
>    check is moved after 'try_module_get()'
>  - in 'af_vsock: update comments for stream sockets', 'connect-oriented'
>    replaced with 'connection-oriented'
>  - in 'loopback/vsock: setup SEQPACKET ops for transport',
>    'loopback/vsock' replaced with 'vsock/loopback'
>
>  v3 -> v4:
>  - SEQPACKET specific metadata moved from packet header to payload
>    and called 'virtio_vsock_seq_hdr'
>  - record integrity check:
>    1) SEQ_END operation was added, which marks end of record.
>    2) Both SEQ_BEGIN and SEQ_END carries counter which is incremented
>       on every marker send.
>  - af_vsock.c: socket operations for STREAM and SEQPACKET call same
>    functions instead of having own "gates" differs only by names:
>    'vsock_seqpacket/stream_getsockopt()' now replaced with
>    'vsock_connectible_getsockopt()'.
>  - af_vsock.c: 'seqpacket_dequeue' callback returns error and flag that
>    record ready. There is no need to return number of copied bytes,
>    because case when record received successfully is checked at virtio
>    transport layer, when SEQ_END is processed. Also user doesn't need
>    number of copied bytes, because 'recv()' from SEQPACKET could return
>    error, length of users's buffer or length of whole record(both are
>    known in af_vsock.c).
>  - af_vsock.c: both wait loops in af_vsock.c(for data and space) moved
>    to separate functions because now both called from several places.
>  - af_vsock.c: 'vsock_assign_transport()' checks that 'new_transport'
>    pointer is not NULL and returns 'ESOCKTNOSUPPORT' instead of 'ENODEV'
>    if failed to use transport.
>  - tools/testing/vsock/vsock_test.c: rename tests
>
>  v2 -> v3:
>  - patches reorganized: split for prepare and implementation patches
>  - local variables are declared in "Reverse Christmas tree" manner
>  - virtio_transport_common.c: valid leXX_to_cpu() for vsock header
>    fields access
>  - af_vsock.c: 'vsock_connectible_*sockopt()' added as shared code
>    between stream and seqpacket sockets.
>  - af_vsock.c: loops in '__vsock_*_recvmsg()' refactored.
>  - af_vsock.c: 'vsock_wait_data()' refactored.
>
>  v1 -> v2:
>  - patches reordered: af_vsock.c related changes now before virtio vsock
>  - patches reorganized: more small patches, where +/- are not mixed
>  - tests for SOCK_SEQPACKET added
>  - all commit messages updated
>  - af_vsock.c: 'vsock_pre_recv_check()' inlined to
>    'vsock_connectible_recvmsg()'
>  - af_vsock.c: 'vsock_assign_transport()' returns ENODEV if transport
>    was not found
>  - virtio_transport_common.c: transport callback for seqpacket dequeue
>  - virtio_transport_common.c: simplified
>    'virtio_transport_recv_connected()'
>  - virtio_transport_common.c: send reset on socket and packet type
> 			      mismatch.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@...persky.com>
>

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