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Date: Thu, 19 Apr 2018 08:18:55 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Mikulas Patocka <mpatocka@...hat.com>,
Eric Dumazet <eric.dumazet@...il.com>,
David Miller <davem@...emloft.net>,
Jason Wang <jasowang@...hat.com>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: Re: [PATCH net] virtio_net: split out ctrl buffer
On Thu, Apr 19, 2018 at 08:01:49AM +0300, Michael S. Tsirkin wrote:
> When sending control commands, virtio net sets up several buffers for
> DMA. The buffers are all part of the net device which means it's
> actually allocated by kvmalloc so in theory (on extreme memory pressure)
> it's possible to get a vmalloc'ed buffer which on some platforms means
> we can't DMA there.
>
> Fix up by moving the DMA buffers out into a separate structure.
>
> Reported-by: Mikulas Patocka <mpatocka@...hat.com>
> Suggested-by: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Ouch forgot to commit a fix. Pls ignore will send v2 now.
> ---
>
> Lightly tested.
> Mikulas, does this address your problem?
>
> drivers/net/virtio_net.c | 68 +++++++++++++++++++++++++++---------------------
> 1 file changed, 39 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7b187ec..82f50e5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -147,6 +147,17 @@ struct receive_queue {
> struct xdp_rxq_info xdp_rxq;
> };
>
> +/* Control VQ buffers: protected by the rtnl lock */
> +struct control_buf {
> + struct virtio_net_ctrl_hdr hdr;
> + virtio_net_ctrl_ack status;
> + struct virtio_net_ctrl_mq mq;
> + u8 promisc;
> + u8 allmulti;
> + u16 vid;
> + u64 offloads;
> +};
> +
> struct virtnet_info {
> struct virtio_device *vdev;
> struct virtqueue *cvq;
> @@ -192,14 +203,7 @@ struct virtnet_info {
> struct hlist_node node;
> struct hlist_node node_dead;
>
> - /* Control VQ buffers: protected by the rtnl lock */
> - struct virtio_net_ctrl_hdr ctrl_hdr;
> - virtio_net_ctrl_ack ctrl_status;
> - struct virtio_net_ctrl_mq ctrl_mq;
> - u8 ctrl_promisc;
> - u8 ctrl_allmulti;
> - u16 ctrl_vid;
> - u64 ctrl_offloads;
> + struct control_buf *ctrl;
>
> /* Ethtool settings */
> u8 duplex;
> @@ -1454,25 +1458,25 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> /* Caller should know better */
> BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
>
> - vi->ctrl_status = ~0;
> - vi->ctrl_hdr.class = class;
> - vi->ctrl_hdr.cmd = cmd;
> + vi->ctrl->status = ~0;
> + vi->ctrl->hdr.class = class;
> + vi->ctrl->hdr.cmd = cmd;
> /* Add header */
> - sg_init_one(&hdr, &vi->ctrl_hdr, sizeof(vi->ctrl_hdr));
> + sg_init_one(&hdr, &vi->ctrl->hdr, sizeof(vi->ctrl->hdr));
> sgs[out_num++] = &hdr;
>
> if (out)
> sgs[out_num++] = out;
>
> /* Add return status. */
> - sg_init_one(&stat, &vi->ctrl_status, sizeof(vi->ctrl_status));
> + sg_init_one(&stat, &vi->ctrl->status, sizeof(vi->ctrl->status));
> sgs[out_num] = &stat;
>
> BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
> virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
>
> if (unlikely(!virtqueue_kick(vi->cvq)))
> - return vi->ctrl_status == VIRTIO_NET_OK;
> + return vi->ctrl->status == VIRTIO_NET_OK;
>
> /* Spin for a response, the kick causes an ioport write, trapping
> * into the hypervisor, so the request should be handled immediately.
> @@ -1481,7 +1485,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> !virtqueue_is_broken(vi->cvq))
> cpu_relax();
>
> - return vi->ctrl_status == VIRTIO_NET_OK;
> + return vi->ctrl->status == VIRTIO_NET_OK;
> }
>
> static int virtnet_set_mac_address(struct net_device *dev, void *p)
> @@ -1593,8 +1597,8 @@ static int _virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
> if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
> return 0;
>
> - vi->ctrl_mq.virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
> - sg_init_one(&sg, &vi->ctrl_mq, sizeof(vi->ctrl_mq));
> + vi->ctrl->mq.virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
> + sg_init_one(&sg, &vi->ctrl->mq, sizeof(vi->ctrl->mq));
>
> if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
> VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg)) {
> @@ -1653,22 +1657,22 @@ static void virtnet_set_rx_mode(struct net_device *dev)
> if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))
> return;
>
> - vi->ctrl_promisc = ((dev->flags & IFF_PROMISC) != 0);
> - vi->ctrl_allmulti = ((dev->flags & IFF_ALLMULTI) != 0);
> + vi->ctrl->promisc = ((dev->flags & IFF_PROMISC) != 0);
> + vi->ctrl->allmulti = ((dev->flags & IFF_ALLMULTI) != 0);
>
> - sg_init_one(sg, &vi->ctrl_promisc, sizeof(vi->ctrl_promisc));
> + sg_init_one(sg, &vi->ctrl->promisc, sizeof(vi->ctrl->promisc));
>
> if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
> VIRTIO_NET_CTRL_RX_PROMISC, sg))
> dev_warn(&dev->dev, "Failed to %sable promisc mode.\n",
> - vi->ctrl_promisc ? "en" : "dis");
> + vi->ctrl->promisc ? "en" : "dis");
>
> - sg_init_one(sg, &vi->ctrl_allmulti, sizeof(vi->ctrl_allmulti));
> + sg_init_one(sg, &vi->ctrl->allmulti, sizeof(vi->ctrl->allmulti));
>
> if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
> VIRTIO_NET_CTRL_RX_ALLMULTI, sg))
> dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
> - vi->ctrl_allmulti ? "en" : "dis");
> + vi->ctrl->allmulti ? "en" : "dis");
>
> uc_count = netdev_uc_count(dev);
> mc_count = netdev_mc_count(dev);
> @@ -1714,8 +1718,8 @@ static int virtnet_vlan_rx_add_vid(struct net_device *dev,
> struct virtnet_info *vi = netdev_priv(dev);
> struct scatterlist sg;
>
> - vi->ctrl_vid = vid;
> - sg_init_one(&sg, &vi->ctrl_vid, sizeof(vi->ctrl_vid));
> + vi->ctrl->vid = vid;
> + sg_init_one(&sg, &vi->ctrl->vid, sizeof(vi->ctrl->vid));
>
> if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
> VIRTIO_NET_CTRL_VLAN_ADD, &sg))
> @@ -1729,8 +1733,8 @@ static int virtnet_vlan_rx_kill_vid(struct net_device *dev,
> struct virtnet_info *vi = netdev_priv(dev);
> struct scatterlist sg;
>
> - vi->ctrl_vid = vid;
> - sg_init_one(&sg, &vi->ctrl_vid, sizeof(vi->ctrl_vid));
> + vi->ctrl->vid = vid;
> + sg_init_one(&sg, &vi->ctrl->vid, sizeof(vi->ctrl->vid));
>
> if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
> VIRTIO_NET_CTRL_VLAN_DEL, &sg))
> @@ -2126,9 +2130,9 @@ static int virtnet_restore_up(struct virtio_device *vdev)
> static int virtnet_set_guest_offloads(struct virtnet_info *vi, u64 offloads)
> {
> struct scatterlist sg;
> - vi->ctrl_offloads = cpu_to_virtio64(vi->vdev, offloads);
> + vi->ctrl->offloads = cpu_to_virtio64(vi->vdev, offloads);
>
> - sg_init_one(&sg, &vi->ctrl_offloads, sizeof(vi->ctrl_offloads));
> + sg_init_one(&sg, &vi->ctrl->offloads, sizeof(vi->ctrl->offloads));
>
> if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_GUEST_OFFLOADS,
> VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET, &sg)) {
> @@ -2351,6 +2355,7 @@ static void virtnet_free_queues(struct virtnet_info *vi)
>
> kfree(vi->rq);
> kfree(vi->sq);
> + kfree(vi->err_ctrl);
> }
>
> static void _free_receive_bufs(struct virtnet_info *vi)
> @@ -2543,6 +2548,9 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
> {
> int i;
>
> + vi->ctrl = kzalloc(sizeof(*vi->ctrl), GFP_KERNEL);
> + if (!vi->ctrl)
> + goto err_ctrl;
> vi->sq = kzalloc(sizeof(*vi->sq) * vi->max_queue_pairs, GFP_KERNEL);
> if (!vi->sq)
> goto err_sq;
> @@ -2571,6 +2579,8 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
> err_rq:
> kfree(vi->sq);
> err_sq:
> + kfree(vq->ctrl);
> +err_ctrl:
> return -ENOMEM;
> }
>
> --
> MST
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