Re: [RFC PATCH v8 15/19] vhost/vsock: enable SEQPACKET for transport

Stefano Garzarella
2021-04-21T09:31:58Z

On Tue, Apr 13, 2021 at 03:46:18PM +0300, Arseny Krasnov wrote:
>This removes:
>1) Ignore of non-stream type of packets.
>This adds:
>1) Handling of SEQPACKET bit: if guest sets features with this bit cleared,
> then SOCK_SEQPACKET support will be disabled.
>2) 'seqpacket_allow()' callback.
>3) Handling of SEQ_EOR bit: when vhost places data in buffers of guest's
> rx queue, keep this bit set only when last piece of data is copied.
>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>---
>v7 -> v8:
> - This patch merged with patch which adds SEQPACKET feature bit to
> virtio transport.
> - It now handles VIRTIO_VSOCK_SEQ_EOR bit(see commit msg).
>
> drivers/vhost/vsock.c | 31 ++++++++++++++++++++++++++++---
> 1 file changed, 28 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 5e78fb719602..0969cdc87830 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -31,7 +31,8 @@
>
> enum {
> VHOST_VSOCK_FEATURES = VHOST_FEATURES |
>- (1ULL << VIRTIO_F_ACCESS_PLATFORM)
>+ (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
>+ (1ULL << VIRTIO_VSOCK_F_SEQPACKET)
> };
>
> enum {
>@@ -112,6 +113,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> size_t nbytes;
> size_t iov_len, payload_len;
> int head;
>+ bool restore_flag = false;
>
> spin_lock_bh(&vsock->send_pkt_list_lock);
> if (list_empty(&vsock->send_pkt_list)) {
>@@ -174,6 +176,12 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> /* Set the correct length in the header */
> pkt->hdr.len = cpu_to_le32(payload_len);
>
>+ if (pkt->off + payload_len < pkt->len &&
>+ pkt->hdr.flags & VIRTIO_VSOCK_SEQ_EOR) {
^
(1)
>+ pkt->hdr.flags &= ~VIRTIO_VSOCK_SEQ_EOR;
^
(2)
>+ restore_flag = true;
>+ }
>+
> nbytes = copy_to_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
> if (nbytes != sizeof(pkt->hdr)) {
> virtio_transport_free_pkt(pkt);
>@@ -181,6 +189,9 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> break;
> }
>
>+ if (restore_flag)
>+ pkt->hdr.flags |= VIRTIO_VSOCK_SEQ_EOR;
^
(3)
In these 3 points we should use cpu_to_le32()/le32_to_cpu().

>+
> nbytes = copy_to_iter(pkt->buf + pkt->off, payload_len,
> &iov_iter);
> if (nbytes != payload_len) {
>@@ -354,8 +365,7 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> return NULL;
> }
>
>- if (le16_to_cpu(pkt->hdr.type) == VIRTIO_VSOCK_TYPE_STREAM)
>- pkt->len = le32_to_cpu(pkt->hdr.len);
>+ pkt->len = le32_to_cpu(pkt->hdr.len);
>
> /* No payload */
> if (!pkt->len)
>@@ -398,6 +408,8 @@ static bool vhost_vsock_more_replies(struct vhost_vsock *vsock)
> return val < vq->num;
> }
>
>+static bool vhost_transport_seqpacket_allow(void);
>+
> static struct virtio_transport vhost_transport = {
> .transport = {
> .module = THIS_MODULE,
>@@ -424,6 +436,10 @@ static struct virtio_transport vhost_transport = {
> .stream_is_active = virtio_transport_stream_is_active,
> .stream_allow =
> virtio_transport_stream_allow,
>
>+ .seqpacket_dequeue = virtio_transport_seqpacket_dequeue,
>+ .seqpacket_enqueue = virtio_transport_seqpacket_enqueue,
>+ .seqpacket_allow = vhost_transport_seqpacket_allow,
>+
> .notify_poll_in = virtio_transport_notify_poll_in,
> .notify_poll_out = virtio_transport_notify_poll_out,
> .notify_recv_init = virtio_transport_notify_recv_init,
>@@ -439,8 +455,14 @@ static struct virtio_transport vhost_transport = {
> },
>
> .send_pkt = vhost_transport_send_pkt,
>+ .seqpacket_allow = false
> };
>
>+static bool vhost_transport_seqpacket_allow(void)
>+{
>+ return vhost_transport.seqpacket_allow;
>+}

I think here it's even worse then virtio_transport.c, because there may
be more instances with different guests and some may require the feature
and some may not, we can't definitely save this information in struct
virtio_transport, we should put it in `struct vhost_vsock`.

>+
> static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> {
> struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
>@@ -785,6 +807,9 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
> goto err;
> }
>
>+ if (features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET))
>+ vhost_transport.seqpacket_allow = true;
>+
> for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
> vq = &vsock->vqs[i];
> mutex_lock(&vq->mutex);
>--
>2.25.1
>