Jason Wang
2014-Nov-13 05:52 UTC
[PATCH 1/2] virito: introduce methods of fixing device features
Buggy host may advertised buggy host features (a usual case is that host advertise a feature whose dependencies were missed). In this case, driver should detect and disable the buggy features by itself. This patch introduces driver specific fix_features() method which is called just before features finalizing to detect and disable buggy features advertised by host. Virtio-net will be the first user. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/virtio/virtio.c | 4 ++++ include/linux/virtio.h | 1 + include/linux/virtio_config.h | 12 ++++++++++++ 3 files changed, 17 insertions(+) diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index df598dd..7001d6e 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -181,6 +181,10 @@ static int virtio_dev_probe(struct device *_d) if (device_features & (1 << i)) set_bit(i, dev->features); + /* Fix buggy features advertised by host */ + if (drv->fix_features) + drv->fix_features(dev); + dev->config->finalize_features(dev); err = drv->probe(dev); diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 65261a7..9d01b54 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -142,6 +142,7 @@ struct virtio_driver { void (*scan)(struct virtio_device *dev); void (*remove)(struct virtio_device *dev); void (*config_changed)(struct virtio_device *dev); + void (*fix_features)(struct virtio_device *dev); #ifdef CONFIG_PM int (*freeze)(struct virtio_device *dev); int (*restore)(struct virtio_device *dev); diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index 7f4ef66..7bd89ea 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -96,6 +96,18 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev, return test_bit(fbit, vdev->features); } +static inline void virtio_disable_feature(struct virtio_device *vdev, + unsigned int fbit) +{ + BUG_ON(fbit >= VIRTIO_TRANSPORT_F_START); + BUG_ON(vdev->config->get_status(vdev) & + ~(VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER)); + + virtio_check_driver_offered_feature(vdev, fbit); + + clear_bit(fbit, vdev->features); +} + static inline struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, vq_callback_t *c, const char *n) -- 1.9.1
Jason Wang
2014-Nov-13 05:52 UTC
[PATCH 2/2] virtio-net: fix buggy features advertised by host
This patch tries to detect the possible buggy features advertised by host and fix 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 fix_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. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- Changes from V1: - fix the cut-and-paste error --- drivers/net/virtio_net.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ec2a8b4..6ce125e 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1948,6 +1948,40 @@ static int virtnet_restore(struct virtio_device *vdev) } #endif +static void virtnet_fix_features(struct virtio_device *dev) +{ + if (!virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VQ)) { + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_RX)) { + pr_warning("Disable VIRTIO_NET_F_CTRL_RX since host " + "does not advertise VIRTIO_NET_F_CTRL_VQ"); + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_RX); + } + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VLAN)) { + pr_warning("Disable VIRTIO_NET_F_CTRL_VLAN since host " + "does not advertise VIRTIO_NET_F_CTRL_VQ"); + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_VLAN); + } + if (virtio_has_feature(dev, VIRTIO_NET_F_GUEST_ANNOUNCE)) { + pr_warning("Disable VIRTIO_NET_F_GUEST_ANNOUNCE since " + "host does not advertise " + "VIRTIO_NET_F_CTRL_VQ"); + virtio_disable_feature(dev, + VIRTIO_NET_F_GUEST_ANNOUNCE); + } + if (virtio_has_feature(dev, VIRTIO_NET_F_MQ)) { + pr_warning("Disable VIRTIO_NET_F_MQ since host " + "does not advertise VIRTIO_NET_F_CTRL_VQ"); + virtio_disable_feature(dev, VIRTIO_NET_F_MQ); + } + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_MAC_ADDR)) { + pr_warning("Disable VIRTIO_NET_F_CTRL_MAC_ADDR since " + "host does not advertise " + "VIRTIO_NET_F_CTRL_VQ"); + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_MAC_ADDR); + } + } +} + static struct virtio_device_id id_table[] = { { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID }, { 0 }, @@ -1975,6 +2009,7 @@ static struct virtio_driver virtio_net_driver = { .probe = virtnet_probe, .remove = virtnet_remove, .config_changed = virtnet_config_changed, + .fix_features = virtnet_fix_features, #ifdef CONFIG_PM_SLEEP .freeze = virtnet_freeze, .restore = virtnet_restore, -- 1.9.1
Wanlong Gao
2014-Nov-13 06:06 UTC
[PATCH 2/2] virtio-net: fix buggy features advertised by host
On 11/13/2014 01:52 PM, Jason Wang wrote:> This patch tries to detect the possible buggy features advertised by host > and fix 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 fix_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. > > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Jason Wang <jasowang at redhat.com> > --- > Changes from V1: > - fix the cut-and-paste error > --- > drivers/net/virtio_net.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index ec2a8b4..6ce125e 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -1948,6 +1948,40 @@ static int virtnet_restore(struct virtio_device *vdev) > } > #endif > > +static void virtnet_fix_features(struct virtio_device *dev) > +{ > + if (!virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VQ)) { > + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_RX)) { > + pr_warning("Disable VIRTIO_NET_F_CTRL_RX since host " > + "does not advertise VIRTIO_NET_F_CTRL_VQ"); > + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_RX); > + } > + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VLAN)) { > + pr_warning("Disable VIRTIO_NET_F_CTRL_VLAN since host " > + "does not advertise VIRTIO_NET_F_CTRL_VQ"); > + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_VLAN); > + } > + if (virtio_has_feature(dev, VIRTIO_NET_F_GUEST_ANNOUNCE)) { > + pr_warning("Disable VIRTIO_NET_F_GUEST_ANNOUNCE since " > + "host does not advertise " > + "VIRTIO_NET_F_CTRL_VQ"); > + virtio_disable_feature(dev, > + VIRTIO_NET_F_GUEST_ANNOUNCE); > + } > + if (virtio_has_feature(dev, VIRTIO_NET_F_MQ)) { > + pr_warning("Disable VIRTIO_NET_F_MQ since host " > + "does not advertise VIRTIO_NET_F_CTRL_VQ"); > + virtio_disable_feature(dev, VIRTIO_NET_F_MQ); > + } > + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_MAC_ADDR)) { > + pr_warning("Disable VIRTIO_NET_F_CTRL_MAC_ADDR since " > + "host does not advertise " > + "VIRTIO_NET_F_CTRL_VQ"); > + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_MAC_ADDR); > + }Can we use a feature array and check with one loop? The current check looks so dup? Thanks, Wanlong Gao> + } > +} > + > static struct virtio_device_id id_table[] = { > { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID }, > { 0 }, > @@ -1975,6 +2009,7 @@ static struct virtio_driver virtio_net_driver = { > .probe = virtnet_probe, > .remove = virtnet_remove, > .config_changed = virtnet_config_changed, > + .fix_features = virtnet_fix_features, > #ifdef CONFIG_PM_SLEEP > .freeze = virtnet_freeze, > .restore = virtnet_restore, >
Cornelia Huck
2014-Nov-13 08:46 UTC
[PATCH 1/2] virito: introduce methods of fixing device features
On Thu, 13 Nov 2014 13:52:53 +0800 Jason Wang <jasowang at redhat.com> wrote: typo in subject-prefix: s/virito/virtio/> Buggy host may advertised buggy host features (a usual case is that host > advertise a feature whose dependencies were missed). In this case, driver > should detect and disable the buggy features by itself. > > This patch introduces driver specific fix_features() method which is called > just before features finalizing to detect and disable buggy features > advertised by host.So the basic problem this patch fixes is that an individual driver may only specify a static set of features but cannot specify any dependencies, right? Adding a sanitizer step makes sense, I guess.> > Virtio-net will be the first user. > > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Jason Wang <jasowang at redhat.com> > --- > drivers/virtio/virtio.c | 4 ++++ > include/linux/virtio.h | 1 + > include/linux/virtio_config.h | 12 ++++++++++++ > 3 files changed, 17 insertions(+) > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index df598dd..7001d6e 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -181,6 +181,10 @@ static int virtio_dev_probe(struct device *_d) > if (device_features & (1 << i)) > set_bit(i, dev->features); > > + /* Fix buggy features advertised by host */ > + if (drv->fix_features) > + drv->fix_features(dev);I'd probably call this "sanitize_features" instead.> + > dev->config->finalize_features(dev); > > err = drv->probe(dev);> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index 7f4ef66..7bd89ea 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -96,6 +96,18 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev, > return test_bit(fbit, vdev->features); > } > > +static inline void virtio_disable_feature(struct virtio_device *vdev, > + unsigned int fbit) > +{ > + BUG_ON(fbit >= VIRTIO_TRANSPORT_F_START); > + BUG_ON(vdev->config->get_status(vdev) & > + ~(VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER));When we add virtio-1 support, we can add a check for FEATURES_OK here, so we're really on the safe side.> + > + virtio_check_driver_offered_feature(vdev, fbit); > + > + clear_bit(fbit, vdev->features); > +} > + > static inline > struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, > vq_callback_t *c, const char *n)The approach looks good to me.
Cornelia Huck
2014-Nov-13 08:53 UTC
[PATCH 2/2] virtio-net: fix buggy features advertised by host
On Thu, 13 Nov 2014 13:52:54 +0800 Jason Wang <jasowang at redhat.com> wrote:> This patch tries to detect the possible buggy features advertised by host > and fix 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 fix_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.That's a qemu device property, right? Might want to mention that, as this line sounds like it is a kernel parameter.> > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Jason Wang <jasowang at redhat.com> > --- > Changes from V1: > - fix the cut-and-paste error > --- > drivers/net/virtio_net.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index ec2a8b4..6ce125e 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -1948,6 +1948,40 @@ static int virtnet_restore(struct virtio_device *vdev) > } > #endif > > +static void virtnet_fix_features(struct virtio_device *dev) > +{ > + if (!virtio_has_feature(dev, VIRTIO_NET_F_CTRL_VQ)) { > + if (virtio_has_feature(dev, VIRTIO_NET_F_CTRL_RX)) { > + pr_warning("Disable VIRTIO_NET_F_CTRL_RX since host " > + "does not advertise VIRTIO_NET_F_CTRL_VQ"); > + virtio_disable_feature(dev, VIRTIO_NET_F_CTRL_RX); > + }You should probably use dev_warn() or so, so that the user can figure out which device the message is for. And perhaps add "buggy hypervisor" to the message to make clear that it's not a guest problem. I also like the suggestion to use a dependency array.
Jason Wang
2014-Nov-13 09:11 UTC
[PATCH 1/2] virito: introduce methods of fixing device features
On 11/13/2014 04:46 PM, Cornelia Huck wrote:> On Thu, 13 Nov 2014 13:52:53 +0800 > Jason Wang <jasowang at redhat.com> wrote: > > typo in subject-prefix: s/virito/virtio/ >Will correct this.>> Buggy host may advertised buggy host features (a usual case is that host >> advertise a feature whose dependencies were missed). In this case, driver >> should detect and disable the buggy features by itself. >> >> This patch introduces driver specific fix_features() method which is called >> just before features finalizing to detect and disable buggy features >> advertised by host. > So the basic problem this patch fixes is that an individual driver may > only specify a static set of features but cannot specify any > dependencies, right?Right, and what even worse is qemu could not handle dependencies as well. So we need fix both sides.> Adding a sanitizer step makes sense, I guess. > >> Virtio-net will be the first user. >> >> Cc: Rusty Russell <rusty at rustcorp.com.au> >> Cc: Michael S. Tsirkin <mst at redhat.com> >> Signed-off-by: Jason Wang <jasowang at redhat.com> >> --- >> drivers/virtio/virtio.c | 4 ++++ >> include/linux/virtio.h | 1 + >> include/linux/virtio_config.h | 12 ++++++++++++ >> 3 files changed, 17 insertions(+) >> >> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c >> index df598dd..7001d6e 100644 >> --- a/drivers/virtio/virtio.c >> +++ b/drivers/virtio/virtio.c >> @@ -181,6 +181,10 @@ static int virtio_dev_probe(struct device *_d) >> if (device_features & (1 << i)) >> set_bit(i, dev->features); >> >> + /* Fix buggy features advertised by host */ >> + if (drv->fix_features) >> + drv->fix_features(dev); > I'd probably call this "sanitize_features" instead.Ok.>> + >> dev->config->finalize_features(dev); >> >> err = drv->probe(dev); >> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h >> index 7f4ef66..7bd89ea 100644 >> --- a/include/linux/virtio_config.h >> +++ b/include/linux/virtio_config.h >> @@ -96,6 +96,18 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev, >> return test_bit(fbit, vdev->features); >> } >> >> +static inline void virtio_disable_feature(struct virtio_device *vdev, >> + unsigned int fbit) >> +{ >> + BUG_ON(fbit >= VIRTIO_TRANSPORT_F_START); >> + BUG_ON(vdev->config->get_status(vdev) & >> + ~(VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER)); > When we add virtio-1 support, we can add a check for FEATURES_OK here, > so we're really on the safe side. >If I read the spec correctly, FEATURES_OK was set only after writing the features bits to device. But we want to sanitize the them before.>> + >> + virtio_check_driver_offered_feature(vdev, fbit); >> + >> + clear_bit(fbit, vdev->features); >> +} >> + >> static inline >> struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, >> vq_callback_t *c, const char *n) > The approach looks good to me. >Thanks for the review.
Rusty Russell
2014-Nov-24 01:08 UTC
[PATCH 1/2] virito: introduce methods of fixing device features
Jason Wang <jasowang at redhat.com> writes:> Buggy host may advertised buggy host features (a usual case is that host > advertise a feature whose dependencies were missed). In this case, driver > should detect and disable the buggy features by itself.Sorry, I've been focussing elsewhere. I would really prefer that drivers offer a "feature_depends" table, which can indicate that feature A depends on feature B, and have the core iterate, complain and fixup as necessary. Is that expressive enough, or do we need more? Thanks, Rusty.
Jason Wang
2014-Nov-26 07:09 UTC
[PATCH 1/2] virito: introduce methods of fixing device features
----- Original Message -----> Jason Wang <jasowang at redhat.com> writes: > > Buggy host may advertised buggy host features (a usual case is that host > > advertise a feature whose dependencies were missed). In this case, driver > > should detect and disable the buggy features by itself. > > Sorry, I've been focussing elsewhere. > > I would really prefer that drivers offer a "feature_depends" table, > which can indicate that feature A depends on feature B, and have the > core iterate, complain and fixup as necessary. > > Is that expressive enough, or do we need more? > > Thanks, > Rusty.I suggested something like this in https://lkml.org/lkml/2014/11/19/132, but Michael does not like it ...
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- [PATCH 1/2] virito: introduce methods of fixing device features
- [PATCH 1/2] virito: introduce methods of fixing device features
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- [PATCH 2/2] virtio-net: fix buggy features advertised by host
- [PATCH 2/2] virtio-net: fix buggy features advertised by host