[PATCH 1/5] VSOCK: support fill mergeable rx buffer in guest

[jiangyiwen]

In driver probing, if virtio has VIRTIO_VSOCK_F_MRG_RXBUF feature,
it will fill mergeable rx buffer, support for host send mergeable
rx buffer. It will fill a page everytime to compact with small
packet and big packet.

Signed-off-by: Yiwen Jiang <jiangyi...@huawei.com>
---
 include/linux/virtio_vsock.h     |  3 ++
 net/vmw_vsock/virtio_transport.c | 72 +++++++++++++++++++++++++++++-----------
 2 files changed, 56 insertions(+), 19 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index e223e26..bf84418 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -14,6 +14,9 @@
 #define VIRTIO_VSOCK_MAX_BUF_SIZE              0xFFFFFFFFUL
 #define VIRTIO_VSOCK_MAX_PKT_BUF_SIZE          (1024 * 64)

+/* Virtio-vsock feature */
+#define VIRTIO_VSOCK_F_MRG_RXBUF 0 /* Host can merge receive buffers. */
+
 enum {
        VSOCK_VQ_RX     = 0, /* for host to guest data */
        VSOCK_VQ_TX     = 1, /* for guest to host data */
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 5d3cce9..2040a9e 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -64,6 +64,7 @@ struct virtio_vsock {
        struct virtio_vsock_event event_list[8];

        u32 guest_cid;
+       bool mergeable;
 };

 static struct virtio_vsock *virtio_vsock_get(void)
@@ -256,6 +257,25 @@ static int virtio_transport_send_pkt_loopback(struct 
virtio_vsock *vsock,
        return 0;
 }

+static int fill_mergeable_rx_buff(struct virtqueue *vq)
+{
+       void *page = NULL;
+       struct scatterlist sg;
+       int err;
+
+       page = (void *)get_zeroed_page(GFP_KERNEL);
+       if (!page)
+               return -ENOMEM;
+
+       sg_init_one(&sg, page, PAGE_SIZE);
+
+       err = virtqueue_add_inbuf(vq, &sg, 1, page, GFP_KERNEL);
+       if (err < 0)
+               free_page((unsigned long) page);
+
+       return err;
+}
+
 static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
 {
        int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
@@ -267,27 +287,33 @@ static void virtio_vsock_rx_fill(struct virtio_vsock 
*vsock)
        vq = vsock->vqs[VSOCK_VQ_RX];

        do {
-               pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
-               if (!pkt)
-                       break;
+               if (vsock->mergeable) {
+                       ret = fill_mergeable_rx_buff(vq);
+                       if (ret)
+                               break;
+               } else {
+                       pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
+                       if (!pkt)
+                               break;

-               pkt->buf = kmalloc(buf_len, GFP_KERNEL);
-               if (!pkt->buf) {
-                       virtio_transport_free_pkt(pkt);
-                       break;
-               }
+                       pkt->buf = kmalloc(buf_len, GFP_KERNEL);
+                       if (!pkt->buf) {
+                               virtio_transport_free_pkt(pkt);
+                               break;
+                       }

-               pkt->len = buf_len;
+                       pkt->len = buf_len;

-               sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
-               sgs[0] = &hdr;
+                       sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
+                       sgs[0] = &hdr;

-               sg_init_one(&buf, pkt->buf, buf_len);
-               sgs[1] = &buf;
-               ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
-               if (ret) {
-                       virtio_transport_free_pkt(pkt);
-                       break;
+                       sg_init_one(&buf, pkt->buf, buf_len);
+                       sgs[1] = &buf;
+                       ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
+                       if (ret) {
+                               virtio_transport_free_pkt(pkt);
+                               break;
+                       }
                }
                vsock->rx_buf_nr++;
        } while (vq->num_free);
@@ -588,6 +614,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
        if (ret < 0)
                goto out_vqs;

+       if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_MRG_RXBUF))
+               vsock->mergeable = true;
+
        vsock->rx_buf_nr = 0;
        vsock->rx_buf_max_nr = 0;
        atomic_set(&vsock->queued_replies, 0);
@@ -640,8 +669,12 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
        vdev->config->reset(vdev);

        mutex_lock(&vsock->rx_lock);
-       while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
-               virtio_transport_free_pkt(pkt);
+       while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX]))) {
+               if (vsock->mergeable)
+                       free_page((unsigned long)(void *)pkt);
+               else
+                       virtio_transport_free_pkt(pkt);
+       }
        mutex_unlock(&vsock->rx_lock);

        mutex_lock(&vsock->tx_lock);
@@ -683,6 +716,7 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
 };

 static unsigned int features[] = {
+       VIRTIO_VSOCK_F_MRG_RXBUF,
 };

 static struct virtio_driver virtio_vsock_driver = {
-- 
1.8.3.1

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