Date:   Tue, 25 May 2021 11:22:09 +0300
From:   Arseny Krasnov <arseny.krasnov@...persky.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
CC:     Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jorgen Hansen <jhansen@...are.com>,
        Colin Ian King <colin.king@...onical.com>,
        Norbert Slusarek <nslusarek@....net>,
        Andra Paraschiv <andraprs@...zon.com>,
        "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 v10 00/18] virtio/vsock: introduce SOCK_SEQPACKET support


On 23.05.2021 15:14, Arseny Krasnov wrote:
> On 21.05.2021 10:55, Stefano Garzarella wrote:
>> Hi Arseny,
>>
>> On Thu, May 20, 2021 at 10:13:53PM +0300, Arseny Krasnov wrote:
>>> 	This patchset implements support of SOCK_SEQPACKET for virtio
>>> transport.
>> I'll carefully review and test this series next Monday, in the mean time 
>> I think we should have at least an agreement about the changes that 
>> regards virtio-spec before merge this series, to avoid any compatibility 
>> issues.
>>
>> Do you plan to send a new version of the specification changes?
>>
>> Thanks,
>> Stefano
> Hello, sorry for long answer. I'm on vacation now, but i plan to send
>
> it in next several days, because with current implementation it is short
>
>
> Thank You

Hello, here is spec patch:

https://lists.oasis-open.org/archives/virtio-comment/202105/msg00017.html

Let's discuss it

Thank You

>>> 	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 not limited as in stream socket,
>>> because same credit logic is used. Difference with stream socket is
>>> that user is not woken up until whole record is received or error
>>> occurred. 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                        |  44 +-
>>> include/linux/virtio_vsock.h                 |   9 +
>>> include/net/af_vsock.h                       |   7 +
>>> .../events/vsock_virtio_transport_common.h   |   5 +-
>>> include/uapi/linux/virtio_vsock.h            |   9 +
>>> net/vmw_vsock/af_vsock.c                     | 465 +++++++++++------
>>> net/vmw_vsock/virtio_transport.c             |  25 +
>>> net/vmw_vsock/virtio_transport_common.c      | 133 ++++-
>>> net/vmw_vsock/vsock_loopback.c               |  11 +
>>> tools/testing/vsock/util.c                   |  32 +-
>>> tools/testing/vsock/util.h                   |   3 +
>>> tools/testing/vsock/vsock_test.c             | 116 ++++
>>> 12 files changed, 672 insertions(+), 187 deletions(-)
>>>
>>> v9 -> v10:
>>> General changelog:
>>> - patch for write serialization removed from patchset
>>> - commit messages rephrased
>>> - RFC tag removed
>>>
>>> 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>
>>>
>>> -- 
>>> 2.25.1
>>>

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