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virtio_net: split out ctrl buffer
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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 it's in theory (on extreme memory
pressure) possible to get a vmalloc'ed buffer which on some platforms
means we can't DMA there.

Fix up by moving the DMA buffers into a separate structure.

Reported-by: Mikulas Patocka <[email protected]>
Suggested-by: Eric Dumazet <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Acked-by: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@mstsirkin @davem330
mstsirkin authored and davem330 committed Apr 19, 2018
1 parent f4ea891 commit 12e5716
Showing 1 changed file with 39 additions and 29 deletions.
68 changes: 39 additions & 29 deletions drivers/net/virtio_net.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -1461,25 +1465,25 @@ 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.
Expand All @@ -1488,7 +1492,7 @@ 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)
Expand Down Expand Up @@ -1600,8 +1604,8 @@ 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)) {
Expand Down Expand Up @@ -1660,22 +1664,22 @@ 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);
Expand Down Expand Up @@ -1721,8 +1725,8 @@ 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))
Expand All @@ -1736,8 +1740,8 @@ 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))
Expand Down Expand Up @@ -2133,9 +2137,9 @@ 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)) {
Expand Down Expand Up @@ -2358,6 +2362,7 @@ static void virtnet_free_queues(struct virtnet_info *vi)

kfree(vi->rq);
kfree(vi->sq);
kfree(vi->ctrl);
}

static void _free_receive_bufs(struct virtnet_info *vi)
Expand Down Expand Up @@ -2550,6 +2555,9 @@ 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;
Expand Down Expand Up @@ -2578,6 +2586,8 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
err_rq:
kfree(vi->sq);
err_sq:
kfree(vi->ctrl);
err_ctrl:
return -ENOMEM;
}

Expand Down

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