Stefano Garzarella
2021-Feb-12 08:07 UTC
[RFC PATCH v4 00/17] virtio/vsock: introduce SOCK_SEQPACKET support
On Fri, Feb 12, 2021 at 09:11:50AM +0300, Arseny Krasnov wrote:> >On 11.02.2021 17:57, Stefano Garzarella wrote: >> Hi Arseny, >> >> On Mon, Feb 08, 2021 at 09:32:59AM +0300, Arseny Krasnov wrote: >>> On 07.02.2021 19:20, Michael S. Tsirkin wrote: >>>> On Sun, Feb 07, 2021 at 06:12:56PM +0300, Arseny Krasnov wrote: >>>>> This patchset impelements support of SOCK_SEQPACKET for virtio >>>>> transport. >>>>> As SOCK_SEQPACKET guarantees to save record boundaries, so to >>>>> do it, two new packet operations were added: first for start of record >>>>> and second to mark end of record(SEQ_BEGIN and SEQ_END later). Also, >>>>> both operations carries metadata - to maintain boundaries and payload >>>>> integrity. Metadata is introduced by adding special header with two >>>>> fields - message count and message length: >>>>> >>>>> struct virtio_vsock_seq_hdr { >>>>> __le32 msg_cnt; >>>>> __le32 msg_len; >>>>> } __attribute__((packed)); >>>>> >>>>> This header is transmitted as payload of SEQ_BEGIN and SEQ_END >>>>> packets(buffer of second virtio descriptor in chain) in the same way as >>>>> data transmitted in RW packets. Payload was chosen as buffer for this >>>>> header to avoid touching first virtio buffer which carries header of >>>>> packet, because someone could check that size of this buffer is equal >>>>> to size of packet header. To send record, packet with start marker is >>>>> sent first(it's header contains length of record and counter), then >>>>> counter is incremented and all data is sent as usual 'RW' packets and >>>>> finally SEQ_END is sent(it also carries counter of message, which is >>>>> counter of SEQ_BEGIN + 1), also after sedning SEQ_END counter is >>>>> incremented again. On receiver's side, length of record is known from >>>>> packet with start record marker. To check that no packets were dropped >>>>> by transport, counters of two sequential SEQ_BEGIN and SEQ_END are >>>>> checked(counter of SEQ_END must be bigger that counter of SEQ_BEGIN by >>>>> 1) and length of data between two markers is compared to length in >>>>> SEQ_BEGIN header. >>>>> Now as packets of one socket are not reordered neither on >>>>> vsock nor on vhost transport layers, such markers allows to restore >>>>> original record on receiver's side. If user's buffer is smaller that >>>>> record 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_EOR' and 'MSG_TRUNC' flags. >>>>> Tests also implemented. >>>>> >>>>> Arseny Krasnov (17): >>>>> 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: separate wait space loop >>>>> af_vsock: implement send logic for SEQPACKET >>>>> af_vsock: rest of SEQPACKET support >>>>> af_vsock: update comments for stream sockets >>>>> virtio/vsock: dequeue callback for SOCK_SEQPACKET >>>>> virtio/vsock: fetch length for SEQPACKET record >>>>> virtio/vsock: add SEQPACKET receive logic >>>>> virtio/vsock: rest of SOCK_SEQPACKET support >>>>> virtio/vsock: setup SEQPACKET ops for transport >>>>> vhost/vsock: setup SEQPACKET ops for transport >>>>> vsock_test: add SOCK_SEQPACKET tests >>>>> loopback/vsock: setup SEQPACKET ops for transport >>>>> virtio/vsock: simplify credit update function API >>>>> >>>>> drivers/vhost/vsock.c | 8 +- >>>>> include/linux/virtio_vsock.h | 15 + >>>>> include/net/af_vsock.h | 9 + >>>>> include/uapi/linux/virtio_vsock.h | 16 + >>>>> net/vmw_vsock/af_vsock.c | 588 +++++++++++++++------- >>>>> net/vmw_vsock/virtio_transport.c | 5 + >>>>> net/vmw_vsock/virtio_transport_common.c | 316 ++++++++++-- >>>>> net/vmw_vsock/vsock_loopback.c | 5 + >>>>> tools/testing/vsock/util.c | 32 +- >>>>> tools/testing/vsock/util.h | 3 + >>>>> tools/testing/vsock/vsock_test.c | 126 +++++ >>>>> 11 files changed, 895 insertions(+), 228 deletions(-) >>>>> >>>>> TODO: >>>>> - What to do, when server doesn't support SOCK_SEQPACKET. In current >>>>> implementation RST is replied in the same way when listening port >>>>> is not found. I think that current RST is enough,because case when >>>>> server doesn't support SEQ_PACKET is same when listener missed(e.g. >>>>> no listener in both cases). >> I think is fine. >> >>>> - virtio spec patch >>> Ok >> Yes, please prepare a patch to discuss the VIRTIO spec changes. >> >> For example for 'virtio_vsock_seq_hdr', I left a comment about 'msg_cnt' >> naming that should be better to discuss with virtio guys. > >Ok, i'll prepare it in v5. So I have to send it both LKML(as one of patches) and > >virtio mailing lists? (e.g. virtio-comment at lists.oasis-open.org)I think you can send the VIRTIO spec patch separately from this series to virtio-comment, maybe CCing virtualization at lists.linux-foundation.org But Michael could correct me :-)> >> >> Anyway, I reviewed this series and I left some comments. >> I think we are in a good shape :-) >Great, thanks for review. I'll consider all review comments in next >version.Great! Stefano