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Message-ID: <5BE134EF.1070009@huawei.com>
Date: Tue, 6 Nov 2018 14:30:07 +0800
From: jiangyiwen <jiangyiwen@...wei.com>
To: Jason Wang <jasowang@...hat.com>, <stefanha@...hat.com>
CC: <netdev@...r.kernel.org>, <kvm@...r.kernel.org>,
<virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH 2/5] VSOCK: support fill data to mergeable rx buffer in
host
On 2018/11/6 11:43, Jason Wang wrote:
>
> On 2018/11/5 下午3:45, jiangyiwen wrote:
>> When vhost support VIRTIO_VSOCK_F_MRG_RXBUF feature,
>> it will merge big packet into rx vq.
>>
>> Signed-off-by: Yiwen Jiang <jiangyiwen@...wei.com>
>> ---
>> drivers/vhost/vsock.c | 117 +++++++++++++++++++++++++++++++-------
>> include/linux/virtio_vsock.h | 1 +
>> include/uapi/linux/virtio_vsock.h | 5 ++
>> 3 files changed, 102 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>> index 34bc3ab..648be39 100644
>> --- a/drivers/vhost/vsock.c
>> +++ b/drivers/vhost/vsock.c
>> @@ -22,7 +22,8 @@
>> #define VHOST_VSOCK_DEFAULT_HOST_CID 2
>>
>> enum {
>> - VHOST_VSOCK_FEATURES = VHOST_FEATURES,
>> + VHOST_VSOCK_FEATURES = VHOST_FEATURES |
>> + (1ULL << VIRTIO_VSOCK_F_MRG_RXBUF),
>> };
>>
>> /* Used to track all the vhost_vsock instances on the system. */
>> @@ -80,6 +81,68 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>> return vsock;
>> }
>>
>> +static int get_rx_bufs(struct vhost_virtqueue *vq,
>> + struct vring_used_elem *heads, int datalen,
>> + unsigned *iovcount, unsigned int quota)
>> +{
>> + unsigned int out, in;
>> + int seg = 0;
>> + int headcount = 0;
>> + unsigned d;
>> + int ret;
>> + /*
>> + * len is always initialized before use since we are always called with
>> + * datalen > 0.
>> + */
>> + u32 uninitialized_var(len);
>> +
>> + while (datalen > 0 && headcount < quota) {
>> + if (unlikely(seg >= UIO_MAXIOV)) {
>> + ret = -ENOBUFS;
>> + goto err;
>> + }
>> +
>> + ret = vhost_get_vq_desc(vq, vq->iov + seg,
>> + ARRAY_SIZE(vq->iov) - seg, &out,
>> + &in, NULL, NULL);
>> + if (unlikely(ret < 0))
>> + goto err;
>> +
>> + d = ret;
>> + if (d == vq->num) {
>> + ret = 0;
>> + goto err;
>> + }
>> +
>> + if (unlikely(out || in <= 0)) {
>> + vq_err(vq, "unexpected descriptor format for RX: "
>> + "out %d, in %d\n", out, in);
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + heads[headcount].id = cpu_to_vhost32(vq, d);
>> + len = iov_length(vq->iov + seg, in);
>> + heads[headcount].len = cpu_to_vhost32(vq, len);
>> + datalen -= len;
>> + ++headcount;
>> + seg += in;
>> + }
>> +
>> + heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
>> + *iovcount = seg;
>> +
>> + /* Detect overrun */
>> + if (unlikely(datalen > 0)) {
>> + ret = UIO_MAXIOV + 1;
>> + goto err;
>> + }
>> + return headcount;
>> +err:
>> + vhost_discard_vq_desc(vq, headcount);
>> + return ret;
>> +}
>
>
> Seems duplicated with the one used by vhost-net.
>
> In packed virtqueue implementation, I plan to move this to vhost.c.
>
Yes, this code is full copied from vhost-net, if it can be packed into
vhost.c, it would be great.
>
>> +
>> static void
>> vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>> struct vhost_virtqueue *vq)
>> @@ -87,22 +150,34 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>> struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
>> bool added = false;
>> bool restart_tx = false;
>> + int mergeable;
>> + size_t vsock_hlen;
>>
>> mutex_lock(&vq->mutex);
>>
>> if (!vq->private_data)
>> goto out;
>>
>> + mergeable = vhost_has_feature(vq, VIRTIO_VSOCK_F_MRG_RXBUF);
>> + /*
>> + * Guest fill page for rx vq in mergeable case, so it will not
>> + * allocate pkt structure, we should reserve size of pkt in advance.
>> + */
>> + if (likely(mergeable))
>> + vsock_hlen = sizeof(struct virtio_vsock_pkt);
>> + else
>> + vsock_hlen = sizeof(struct virtio_vsock_hdr);
>> +
>> /* Avoid further vmexits, we're already processing the virtqueue */
>> vhost_disable_notify(&vsock->dev, vq);
>>
>> for (;;) {
>> struct virtio_vsock_pkt *pkt;
>> struct iov_iter iov_iter;
>> - unsigned out, in;
>> + unsigned out = 0, in = 0;
>> size_t nbytes;
>> size_t len;
>> - int head;
>> + s16 headcount;
>>
>> spin_lock_bh(&vsock->send_pkt_list_lock);
>> if (list_empty(&vsock->send_pkt_list)) {
>> @@ -116,16 +191,9 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>> list_del_init(&pkt->list);
>> spin_unlock_bh(&vsock->send_pkt_list_lock);
>>
>> - head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
>> - &out, &in, NULL, NULL);
>> - if (head < 0) {
>> - spin_lock_bh(&vsock->send_pkt_list_lock);
>> - list_add(&pkt->list, &vsock->send_pkt_list);
>> - spin_unlock_bh(&vsock->send_pkt_list_lock);
>> - break;
>> - }
>> -
>> - if (head == vq->num) {
>> + headcount = get_rx_bufs(vq, vq->heads, vsock_hlen + pkt->len,
>> + &in, likely(mergeable) ? UIO_MAXIOV : 1);
>> + if (headcount <= 0) {
>> spin_lock_bh(&vsock->send_pkt_list_lock);
>> list_add(&pkt->list, &vsock->send_pkt_list);
>> spin_unlock_bh(&vsock->send_pkt_list_lock);
>> @@ -133,19 +201,13 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>> /* We cannot finish yet if more buffers snuck in while
>> * re-enabling notify.
>> */
>> - if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
>> + if (!headcount && unlikely(vhost_enable_notify(&vsock->dev, vq))) {
>> vhost_disable_notify(&vsock->dev, vq);
>> continue;
>> }
>> break;
>> }
>>
>> - if (out) {
>> - virtio_transport_free_pkt(pkt);
>> - vq_err(vq, "Expected 0 output buffers, got %u\n", out);
>> - break;
>> - }
>> -
>> len = iov_length(&vq->iov[out], in);
>> iov_iter_init(&iov_iter, READ, &vq->iov[out], in, len);
>>
>> @@ -156,6 +218,19 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>> break;
>> }
>>
>> + if (likely(mergeable)) {
>> + pkt->mrg_rxbuf_hdr.num_buffers = cpu_to_le16(headcount);
>> + nbytes = copy_to_iter(&pkt->mrg_rxbuf_hdr,
>> + sizeof(pkt->mrg_rxbuf_hdr), &iov_iter);
>> + if (nbytes != sizeof(pkt->mrg_rxbuf_hdr)) {
>> + virtio_transport_free_pkt(pkt);
>> + vq_err(vq, "Faulted on copying rxbuf hdr\n");
>> + break;
>> + }
>> + iov_iter_advance(&iov_iter, (vsock_hlen -
>> + sizeof(pkt->mrg_rxbuf_hdr) - sizeof(pkt->hdr)));
>> + }
>> +
>> nbytes = copy_to_iter(pkt->buf, pkt->len, &iov_iter);
>> if (nbytes != pkt->len) {
>> virtio_transport_free_pkt(pkt);
>> @@ -163,7 +238,7 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>> break;
>> }
>>
>> - vhost_add_used(vq, head, sizeof(pkt->hdr) + pkt->len);
>> + vhost_add_used_n(vq, vq->heads, headcount);
>> added = true;
>
>
> Looks rather similar to vhost-net mergeable rx buffer implementation. Another proof of using vhost-net.
>
> Thanks
Yes.
>
>
>>
>> if (pkt->reply) {
>> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>> index bf84418..da9e1fe 100644
>> --- a/include/linux/virtio_vsock.h
>> +++ b/include/linux/virtio_vsock.h
>> @@ -50,6 +50,7 @@ struct virtio_vsock_sock {
>>
>> struct virtio_vsock_pkt {
>> struct virtio_vsock_hdr hdr;
>> + struct virtio_vsock_mrg_rxbuf_hdr mrg_rxbuf_hdr;
>> struct work_struct work;
>> struct list_head list;
>> /* socket refcnt not held, only use for cancellation */
>> diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
>> index 1d57ed3..2292f30 100644
>> --- a/include/uapi/linux/virtio_vsock.h
>> +++ b/include/uapi/linux/virtio_vsock.h
>> @@ -63,6 +63,11 @@ struct virtio_vsock_hdr {
>> __le32 fwd_cnt;
>> } __attribute__((packed));
>>
>> +/* It add mergeable rx buffers feature */
>> +struct virtio_vsock_mrg_rxbuf_hdr {
>> + __le16 num_buffers; /* number of mergeable rx buffers */
>> +} __attribute__((packed));
>> +
>> enum virtio_vsock_type {
>> VIRTIO_VSOCK_TYPE_STREAM = 1,
>> };
>
> .
>
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