From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
Cornelia Huck <cornelia.huck@de.ibm.com>,
Wanlong Gao <gaowanlong@cn.fujitsu.com>
Subject: Re: [PATCH V3 2/2] virtio-net: sanitize buggy features advertised by host
Date: Mon, 17 Nov 2014 12:08:38 +0200 [thread overview]
Message-ID: <20141117100838.GD20133@redhat.com> (raw)
In-Reply-To: <1416215838-21700-2-git-send-email-jasowang@redhat.com>
On Mon, Nov 17, 2014 at 05:17:18PM +0800, Jason Wang wrote:
> This patch tries to detect the possible buggy features advertised by host
> and sanitize them. One example is booting virtio-net with only ctrl_vq
> disabled, qemu may still advertise many features which depends on it. This
> will trigger several BUG()s in virtnet_send_command().
>
> This patch utilizes the sanitize_features() method, and disables all
> features that depends on ctrl_vq if it was not advertised.
>
> This fixes the crash when booting with ctrl_vq=off using qemu.
>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
So I'm not sure this is useful.
The spec says:
The device MUST NOT offer a feature which requires another feature which
was not offered.
So this is a buggy hypervisor, and I believe we should just fail probe.
This can be done without crashing, and is generally a better
idea that second-guessing what hypervisor wants us to do.
However, assuming that we do want this change:
This can be replaced with a table driven design in virtio core, but
since you chose to open code it, I would drop table below altogether.
Just make it
if (!virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VQ)) {
virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_RX);
virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_VLAN);
virtio_disable_feature(dev, VIRTIO_NET_F_GUEST_ANNOUNCE);
virtio_disable_feature(dev, VIRTIO_NET_F_MQ);
virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_MAC_ADDR);
}
> ---
> Changes from V1:
> - fix the cut-and-paste error
> Changes from V2:
> - loop through an array of feature bits
> - switch to use dev_warn()
> ---
> drivers/net/virtio_net.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ec2a8b4..6fadd8c 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1948,6 +1948,31 @@ static int virtnet_restore(struct virtio_device *vdev)
> }
> #endif
>
> +static void virtnet_sanitize_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
> + };
This is not the only dependency: checksums
have dependencies too. See virtio 1.0 spec.
> + int i;
> +
> + if (!virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VQ)) {
> + for (i = 0; i < ARRAY_SIZE(features_for_ctrl_vq); i++) {
> + unsigned int f = features_for_ctrl_vq[i];
> + if (virtio_has_feature(dev, f)) {
> + virtio_disable_feature(dev, f);
> + dev_warn(&dev->dev,
> + "buggy hyperviser: disable feature "
> + "0x%x since VIRTIO_NET_F_CTRL_VQ was "
> + "not advertised.\n", f);
> + }
> + }
> + }
> +}
> +
> static struct virtio_device_id id_table[] = {
> { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
> { 0 },
> @@ -1975,6 +2000,7 @@ static struct virtio_driver virtio_net_driver = {
> .probe = virtnet_probe,
> .remove = virtnet_remove,
> .config_changed = virtnet_config_changed,
> + .sanitize_features = virtnet_sanitize_features,
> #ifdef CONFIG_PM_SLEEP
> .freeze = virtnet_freeze,
> .restore = virtnet_restore,
> --
> 1.9.1
next prev parent reply other threads:[~2014-11-17 10:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-17 9:17 [PATCH V3 1/2] virtio: introduce methods of sanitizing device features Jason Wang
2014-11-17 9:17 ` [PATCH V3 2/2] virtio-net: sanitize buggy features advertised by host Jason Wang
2014-11-17 10:08 ` Michael S. Tsirkin [this message]
2014-11-18 3:03 ` Jason Wang
2014-11-18 11:02 ` Michael S. Tsirkin
2014-11-17 9:37 ` [PATCH V3 1/2] virtio: introduce methods of sanitizing device features Michael S. Tsirkin
2014-11-17 9:44 ` Cornelia Huck
2014-11-17 10:11 ` Michael S. Tsirkin
2014-11-17 10:20 ` Cornelia Huck
2014-11-17 10:28 ` Michael S. Tsirkin
2014-11-17 11:20 ` Cornelia Huck
2014-11-18 3:23 ` Jason Wang
2014-11-18 11:04 ` Michael S. Tsirkin
2014-11-19 3:00 ` Jason Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141117100838.GD20133@redhat.com \
--to=mst@redhat.com \
--cc=cornelia.huck@de.ibm.com \
--cc=gaowanlong@cn.fujitsu.com \
--cc=jasowang@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rusty@rustcorp.com.au \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).