Linux Virtualization - Nov 2014 - [PATCH net V5] virtio-net: validate features during probe

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.

Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
Cc: Wanlong Gao <gaowanlong at cn.fujitsu.com>
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: Jason Wang <jasowang at redhat.com>
---
Changes from V1:
- Drop NETIF_F_*_UFO from checklist
Changes from V2:
- only check the features for ctrl vq (this fix the real bug)
- better error message and simplify API
Changes from V3:
- pass dbit directly and even better error message
- typo fix
Changes from v4:
- add "device" before "advertise"
---
 drivers/net/virtio_net.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index ec2a8b4..b0bc8ea 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1673,6 +1673,40 @@ static const struct attribute_group
virtio_net_mrg_rx_group = {
 };
 #endif
 
+static bool virtnet_fail_on_feature(struct virtio_device *vdev,
+				    unsigned int fbit,
+				    const char *fname, const char *dname)
+{
+	if (!virtio_has_feature(vdev, fbit))
+		return false;
+
+	dev_err(&vdev->dev, "device advertises feature %s but not
%s",
+		fname, dname);
+
+	return true;
+}
+
+#define VIRTNET_FAIL_ON(vdev, fbit, dbit)			\
+	virtnet_fail_on_feature(vdev, fbit, #fbit, dbit)
+
+static bool virtnet_validate_features(struct virtio_device *vdev)
+{
+	if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
+	    (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX,
+			     "VIRTIO_NET_F_CTRL_VQ") ||
+	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN,
+			     "VIRTIO_NET_F_CTRL_VQ") ||
+	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE,
+			     "VIRTIO_NET_F_CTRL_VQ") ||
+	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ, "VIRTIO_NET_F_CTRL_VQ")
||
+	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
+			     "VIRTIO_NET_F_CTRL_VQ"))) {
+		return false;
+	}
+
+	return true;
+}
+
 static int virtnet_probe(struct virtio_device *vdev)
 {
 	int i, err;
@@ -1680,6 +1714,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 	struct virtnet_info *vi;
 	u16 max_queue_pairs;
 
+	if (!virtnet_validate_features(vdev))
+		return -EINVAL;
+
 	/* Find if host supports multiqueue virtio_net device */
 	err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ,
 				   struct virtio_net_config,
-- 
1.9.1

On Thu, 20 Nov 2014 17:03:05 +0800
Jason Wang <jasowang at redhat.com> wrote:
> 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.
> 
> Cc: Rusty Russell <rusty at rustcorp.com.au>
> Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> Cc: Wanlong Gao <gaowanlong at cn.fujitsu.com>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
> Signed-off-by: Jason Wang <jasowang at redhat.com>
> +static bool virtnet_validate_features(struct virtio_device *vdev)
> +{
> +	if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
> +	    (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX,
> +			     "VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN,
> +			     "VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE,
> +			     "VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ,
"VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
> +			     "VIRTIO_NET_F_CTRL_VQ"))) {
> +		return false;
> +	}
> +
> +	return true;
> +}
I still think it may make sense to print all incorrectly set bits, but
let's just fix the BUG() trigger for now.

Acked-by: Cornelia Huck <cornelia.huck at de.ibm.com>

On 11/20/2014 05:48 PM, Cornelia Huck wrote:
> On Thu, 20 Nov 2014 17:03:05 +0800
> Jason Wang <jasowang at redhat.com> wrote:
>
>> 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.
>>
>> Cc: Rusty Russell <rusty at rustcorp.com.au>
>> Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
>> Cc: Wanlong Gao <gaowanlong at cn.fujitsu.com>
>> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
>> Signed-off-by: Jason Wang <jasowang at redhat.com>
>> +static bool virtnet_validate_features(struct virtio_device *vdev)
>> +{
>> +	if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
>> +	    (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX,
>> +			     "VIRTIO_NET_F_CTRL_VQ") ||
>> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN,
>> +			     "VIRTIO_NET_F_CTRL_VQ") ||
>> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE,
>> +			     "VIRTIO_NET_F_CTRL_VQ") ||
>> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ,
"VIRTIO_NET_F_CTRL_VQ") ||
>> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
>> +			     "VIRTIO_NET_F_CTRL_VQ"))) {
>> +		return false;
>> +	}
>> +
>> +	return true;
>> +}
> I still think it may make sense to print all incorrectly set bits, but
> let's just fix the BUG() trigger for now.
>
> Acked-by: Cornelia Huck <cornelia.huck at de.ibm.com>
>
Right, will do it in the future.

Thanks

On Thu, Nov 20, 2014 at 05:03:05PM +0800, Jason Wang
wrote:
> 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.
> 
> Cc: Rusty Russell <rusty at rustcorp.com.au>
> Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> Cc: Wanlong Gao <gaowanlong at cn.fujitsu.com>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
> Signed-off-by: Jason Wang <jasowang at redhat.com>

Acked-by: Michael S. Tsirkin <mst at redhat.com>

Cc DaveM to pick up the patch.
> ---
> Changes from V1:
> - Drop NETIF_F_*_UFO from checklist
> Changes from V2:
> - only check the features for ctrl vq (this fix the real bug)
> - better error message and simplify API
> Changes from V3:
> - pass dbit directly and even better error message
> - typo fix
> Changes from v4:
> - add "device" before "advertise"
> ---
>  drivers/net/virtio_net.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ec2a8b4..b0bc8ea 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1673,6 +1673,40 @@ static const struct attribute_group
virtio_net_mrg_rx_group = {
>  };
>  #endif
>  
> +static bool virtnet_fail_on_feature(struct virtio_device *vdev,
> +				    unsigned int fbit,
> +				    const char *fname, const char *dname)
> +{
> +	if (!virtio_has_feature(vdev, fbit))
> +		return false;
> +
> +	dev_err(&vdev->dev, "device advertises feature %s but not
%s",
> +		fname, dname);
> +
> +	return true;
> +}
> +
> +#define VIRTNET_FAIL_ON(vdev, fbit, dbit)			\
> +	virtnet_fail_on_feature(vdev, fbit, #fbit, dbit)
> +
> +static bool virtnet_validate_features(struct virtio_device *vdev)
> +{
> +	if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
> +	    (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX,
> +			     "VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN,
> +			     "VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE,
> +			     "VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ,
"VIRTIO_NET_F_CTRL_VQ") ||
> +	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
> +			     "VIRTIO_NET_F_CTRL_VQ"))) {
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
>  static int virtnet_probe(struct virtio_device *vdev)
>  {
>  	int i, err;
> @@ -1680,6 +1714,9 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	struct virtnet_info *vi;
>  	u16 max_queue_pairs;
>  
> +	if (!virtnet_validate_features(vdev))
> +		return -EINVAL;
> +
>  	/* Find if host supports multiqueue virtio_net device */
>  	err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ,
>  				   struct virtio_net_config,
> -- 
> 1.9.1

From: Jason Wang <jasowang at redhat.com>
Date: Thu, 20 Nov 2014 17:03:05 +0800
> 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.
> 
> Cc: Rusty Russell <rusty at rustcorp.com.au>
> Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> Cc: Wanlong Gao <gaowanlong at cn.fujitsu.com>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
> Signed-off-by: Jason Wang <jasowang at redhat.com>
Applied, thanks.