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vhost: vsock: add weight support

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This patch will check the weight and exit the loop if we exceeds the
weight. This is useful for preventing vsock kthread from hogging cpu
which is guest triggerable. The weight can help to avoid starving the
request from on direction while another direction is being processed.

The value of weight is picked from vhost-net.

This addresses CVE-2019-3900.

Cc: Stefan Hajnoczi <stefanha@redhat.com>
Fixes: 433fc58e6b ("VSOCK: Introduce vhost_vsock.ko")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Jason Wang 2019-05-17 00:29:51 -04:00 committed by Michael S. Tsirkin
parent e2412c07f8
commit e79b431fb9
1 changed files with 10 additions and 6 deletions
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16
drivers/vhost/vsock.c
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@ -86,6 +86,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
struct vhost_virtqueue *vq)
{
struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
int pkts = 0, total_len = 0;
bool added = false;
bool restart_tx = false;
@ -97,7 +98,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
/* Avoid further vmexits, we're already processing the virtqueue */
vhost_disable_notify(&vsock->dev, vq);
for (;;) {
do {
struct virtio_vsock_pkt *pkt;
struct iov_iter iov_iter;
unsigned out, in;
@ -182,8 +183,9 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
*/
virtio_transport_deliver_tap_pkt(pkt);
total_len += pkt->len;
virtio_transport_free_pkt(pkt);
}
} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
if (added)
vhost_signal(&vsock->dev, vq);
@ -358,7 +360,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
dev);
struct virtio_vsock_pkt *pkt;
int head;
int head, pkts = 0, total_len = 0;
unsigned int out, in;
bool added = false;
@ -368,7 +370,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
goto out;
vhost_disable_notify(&vsock->dev, vq);
for (;;) {
do {
u32 len;
if (!vhost_vsock_more_replies(vsock)) {
@ -409,9 +411,11 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
else
virtio_transport_free_pkt(pkt);
vhost_add_used(vq, head, sizeof(pkt->hdr) + len);
len += sizeof(pkt->hdr);
vhost_add_used(vq, head, len);
total_len += len;
added = true;
}
} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
no_more_replies:
if (added)