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: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Andy Lutomirski <luto@kernel.org>
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index d8838ded..f94ab78 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -140,6 +140,12 @@
/* 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 @@
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 @@
!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 @@
{
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 @@
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);