On Wed, Nov 19, 2014 at 02:35:39PM +0800, Jason Wang wrote:
> This patch validates feature dependencies during probe and fail the probing
> if a dependency is missed. This fixes the issues of hitting BUG()
> when qemu fails to advertise features correctly. One example is booting
> guest with ctrl_vq=off through qemu.
>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
> Cc: Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 93 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ec2a8b4..4a0ad46 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1673,6 +1673,95 @@ static const struct attribute_group virtio_net_mrg_rx_group = {
> };
> #endif
>
> +static int virtnet_validate_features(struct virtio_device *dev,
> + unsigned int *table,
> + int table_size,
> + unsigned int feature)
> +{
> + int i;
> +
> + if (!virtio_has_feature(dev, feature)) {
> + for (i = 0; i < table_size; i++) {
> + unsigned int f = table[i];
> +
> + if (virtio_has_feature(dev, f)) {
> + dev_err(&dev->dev,
> + "buggy hyperviser: feature 0x%x was advertised but its dependency 0x%x was not",
This line's way too long.
> + f, feature);
> + return -EINVAL;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int virtnet_check_features(struct virtio_device *dev)
> +{
> + unsigned int features_for_ctrl_vq[] = {
> + VIRTIO_NET_F_CTRL_RX,
> + VIRTIO_NET_F_CTRL_VLAN,
> + VIRTIO_NET_F_GUEST_ANNOUNCE,
> + VIRTIO_NET_F_MQ,
> + VIRTIO_NET_F_CTRL_MAC_ADDR
> + };
> + unsigned int features_for_guest_csum[] = {
> + VIRTIO_NET_F_GUEST_TSO4,
> + VIRTIO_NET_F_GUEST_TSO6,
> + VIRTIO_NET_F_GUEST_ECN,
> + VIRTIO_NET_F_GUEST_UFO,
> + };
> + unsigned int features_for_host_csum[] = {
> + VIRTIO_NET_F_HOST_TSO4,
> + VIRTIO_NET_F_HOST_TSO6,
> + VIRTIO_NET_F_HOST_ECN,
> + VIRTIO_NET_F_HOST_UFO,
> + };
> + int err;
> +
> + err = virtnet_validate_features(dev, features_for_ctrl_vq,
> + ARRAY_SIZE(features_for_ctrl_vq),
> + VIRTIO_NET_F_CTRL_VQ);
> + if (err)
> + return err;
> +
> + err = virtnet_validate_features(dev, features_for_guest_csum,
> + ARRAY_SIZE(features_for_guest_csum),
> + VIRTIO_NET_F_GUEST_CSUM);
> + if (err)
> + return err;
> +
> + err = virtnet_validate_features(dev, features_for_host_csum,
> + ARRAY_SIZE(features_for_host_csum),
> + VIRTIO_NET_F_CSUM);
> + if (err)
> + return err;
> +
> + if (virtio_has_feature(dev, VIRTIO_NET_F_GUEST_ECN) &&
> + (!virtio_has_feature(dev, VIRTIO_NET_F_GUEST_TSO4) ||
> + !virtio_has_feature(dev, VIRTIO_NET_F_GUEST_TSO6))) {
> + dev_err(&dev->dev,
> + "buggy hyperviser: feature 0x%x was advertised but its dependency 0x%x or 0x%x was not",
> + VIRTIO_NET_F_GUEST_ECN,
> + VIRTIO_NET_F_GUEST_TSO4,
> + VIRTIO_NET_F_GUEST_TSO6);
> + return -EINVAL;
> + }
> +
> + if (virtio_has_feature(dev, VIRTIO_NET_F_HOST_ECN) &&
> + (!virtio_has_feature(dev, VIRTIO_NET_F_HOST_TSO4) ||
> + !virtio_has_feature(dev, VIRTIO_NET_F_HOST_TSO6))) {
> + dev_err(&dev->dev,
> + "buggy hyperviser: feature 0x%x was advertised but its dependency 0x%x or 0x%x was not",
> + VIRTIO_NET_F_HOST_ECN,
> + VIRTIO_NET_F_HOST_TSO4,
> + VIRTIO_NET_F_HOST_TSO6);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static int virtnet_probe(struct virtio_device *vdev)
> {
> int i, err;
> @@ -1680,6 +1769,10 @@ static int virtnet_probe(struct virtio_device *vdev)
> struct virtnet_info *vi;
> u16 max_queue_pairs;
>
> + err = virtnet_check_features(vdev);
> + if (err)
> + return -EINVAL;
> +
> /* Find if host supports multiqueue virtio_net device */
> err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ,
> struct virtio_net_config,
The API seems too complex, and you still had to open-code ECN logic.
Just open-code most of it. You can use a helper macro to output a
friendly message without code duplication.
For example like the below (completely untested)?
I would also like to split things: dependencies on
VIRTIO_NET_F_CTRL_VQ might go into this kernel,
since they help fix BUG.
Others should wait since they don't fix any crashes, and there's a small
chance of a regression for some hypervisor in the field.
-->
virtio-net: friendlier handling of misconfigured hypervisors
We currently trigger BUG when VIRTIO_NET_F_CTRL_VQ
is not set but one of features depending on it is.
That's not a friendly way to report errors to
hypervisors.
Let's check, and fail probe instead.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 26e1330..7a7d1a3 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1673,6 +1673,21 @@ static const struct attribute_group virtio_net_mrg_rx_group = {
};
#endif
+bool __virtnet_fail_on_feature(struct virtio_device *vdev, unsigned int fbit,
+ const char *fname)
+{
+ if (!virtio_has_feature(vdev, fbit))
+ return false;
+
+ dev_err(&dev->dev, "missing requirements for feature bit %d: %s\n",
+ fbit, fname);
+
+ return true;
+}
+
+#define VIRTNET_FAIL_ON(vdev, fbit) \
+ __virtnet_fail_on_feature(vdev, fbit, #fbit)
+
static int virtnet_probe(struct virtio_device *vdev)
{
int i, err;
@@ -1680,6 +1695,14 @@ static int virtnet_probe(struct virtio_device *vdev)
struct virtnet_info *vi;
u16 max_queue_pairs;
+ if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
+ (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX) ||
+ VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN) ||
+ VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) ||
+ VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ) ||
+ VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)))
+ return -EINVAL;
+
/* Find if host supports multiqueue virtio_net device */
err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ,
struct virtio_net_config,
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