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Commit 2ac46030 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio-net: Stop doing DMA from the stack 



Once virtio starts using the DMA API, we won't be able to safely DMA
from the stack.  virtio-net does a couple of config DMA requests
from small stack buffers -- switch to using dynamically-allocated
memory.

This should have no effect on any performance-critical code paths.

Reported-by: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Tested-by: default avatarAndy Lutomirski <luto@kernel.org>
parent 527e9316

drivers/net/virtio_net.c

+19 −15
Original line number Diff line number Diff line
@@ -140,6 +140,12 @@ struct virtnet_info { 


	/* CPU hot plug notifier */

	struct notifier_block nb;



	/* Control VQ buffers: protected by the rtnl lock */

	struct virtio_net_ctrl_hdr ctrl_hdr;

	virtio_net_ctrl_ack ctrl_status;

	u8 ctrl_promisc;

	u8 ctrl_allmulti;

};



struct padded_vnet_hdr {
@@ -976,31 +982,30 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd, 
				 struct scatterlist *out)

{

	struct scatterlist *sgs[4], hdr, stat;

	struct virtio_net_ctrl_hdr ctrl;

	virtio_net_ctrl_ack status = ~0;

	unsigned out_num = 0, tmp;



	/* Caller should know better */

	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));



	ctrl.class = class;

	ctrl.cmd = cmd;

	vi->ctrl_status = ~0;

	vi->ctrl_hdr.class = class;

	vi->ctrl_hdr.cmd = cmd;

	/* Add header */

	sg_init_one(&hdr, &ctrl, sizeof(ctrl));

	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, &status, sizeof(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 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.
@@ -1009,7 +1014,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd, 
	       !virtqueue_is_broken(vi->cvq))

		cpu_relax();



	return status == VIRTIO_NET_OK;

	return vi->ctrl_status == VIRTIO_NET_OK;

}



static int virtnet_set_mac_address(struct net_device *dev, void *p)
@@ -1151,7 +1156,6 @@ static void virtnet_set_rx_mode(struct net_device *dev) 
{

	struct virtnet_info *vi = netdev_priv(dev);

	struct scatterlist sg[2];

	u8 promisc, allmulti;

	struct virtio_net_ctrl_mac *mac_data;

	struct netdev_hw_addr *ha;

	int uc_count;
@@ -1163,22 +1167,22 @@ static void virtnet_set_rx_mode(struct net_device *dev) 
	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))

		return;



	promisc = ((dev->flags & IFF_PROMISC) != 0);

	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, &promisc, sizeof(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",

			 promisc ? "en" : "dis");

			 vi->ctrl_promisc ? "en" : "dis");



	sg_init_one(sg, &allmulti, sizeof(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",

			 allmulti ? "en" : "dis");

			 vi->ctrl_allmulti ? "en" : "dis");



	uc_count = netdev_uc_count(dev);

	mc_count = netdev_mc_count(dev);