* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-23 20:21 ` Alistair Delva
@ 2019-12-24 2:49 ` Jason Wang
2020-01-05 11:16 ` Michael S. Tsirkin
2019-12-24 2:49 ` Jason Wang
` (4 subsequent siblings)
5 siblings, 1 reply; 19+ messages in thread
From: Jason Wang @ 2019-12-24 2:49 UTC (permalink / raw)
To: Alistair Delva, Willem de Bruijn
Cc: Michael S. Tsirkin, LKML, David S. Miller, virtualization,
Network Development
On 2019/12/24 上午4:21, Alistair Delva wrote:
> On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> <willemdebruijn.kernel@gmail.com> wrote:
>> On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
>> <willemdebruijn.kernel@gmail.com> wrote:
>>> 00fffe0ff0 DR7: 0000000000000400
>>>>> Call Trace:
>>>>> ? preempt_count_add+0x58/0xb0
>>>>> ? _raw_spin_lock_irqsave+0x36/0x70
>>>>> ? _raw_spin_unlock_irqrestore+0x1a/0x40
>>>>> ? __wake_up+0x70/0x190
>>>>> virtnet_set_features+0x90/0xf0 [virtio_net]
>>>>> __netdev_update_features+0x271/0x980
>>>>> ? nlmsg_notify+0x5b/0xa0
>>>>> dev_disable_lro+0x2b/0x190
>>>>> ? inet_netconf_notify_devconf+0xe2/0x120
>>>>> devinet_sysctl_forward+0x176/0x1e0
>>>>> proc_sys_call_handler+0x1f0/0x250
>>>>> proc_sys_write+0xf/0x20
>>>>> __vfs_write+0x3e/0x190
>>>>> ? __sb_start_write+0x6d/0xd0
>>>>> vfs_write+0xd3/0x190
>>>>> ksys_write+0x68/0xd0
>>>>> __ia32_sys_write+0x14/0x20
>>>>> do_fast_syscall_32+0x86/0xe0
>>>>> entry_SYSENTER_compat+0x7c/0x8e
>>>>>
>>>>> A similar crash will likely trigger when enabling XDP.
>>>>>
>>>>> Reported-by: Alistair Delva <adelva@google.com>
>>>>> Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
>>>>> Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
>>>>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>>>>> ---
>>>>>
>>>>> Lightly tested.
>>>>>
>>>>> Alistair, could you please test and confirm that this resolves the
>>>>> crash for you?
>>>> This patch doesn't work. The reason is that NETIF_F_LRO is also turned
>>>> on by TSO4/TSO6, which your patch didn't check for. So it ends up
>>>> going through the same path and crashing in the same way.
>>>>
>>>> if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>>>> virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
>>>> dev->features |= NETIF_F_LRO;
>>>>
>>>> It sounds like this patch is fixing something slightly differently to
>>>> my patch fixed. virtnet_set_features() doesn't care about
>>>> GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
>>>> is zero, it will call virtnet_set_guest_offloads(), which triggers the
>>>> crash.
>>>
>>> Interesting. It's surprising that it is trying to configure a flag
>>> that is not configurable, i.e., absent from dev->hw_features
>>> after Michael's change.
>>>
>>>> So either we need to ensure NETIF_F_LRO is never set, or
>>> LRO might be available, just not configurable. Indeed this was what I
>>> observed in the past.
>> dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
>> I guess is a reasonable assumption, just not necessarily the case in
>> virtio_net.
>>
>> So I think we need both patches. Correctly mark the feature as fixed
>> by removing from dev->hw_features and also ignore the request from
>> dev_disable_lro, which does not check for this.
> Something like this maybe:
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d7d5434cc5d..0556f42b0fb5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> u64 offloads;
> int err;
>
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> + return 0;
> +
> if ((dev->features ^ features) & NETIF_F_LRO) {
> if (vi->xdp_queue_pairs)
> return -EBUSY;
> @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> if (!virtnet_validate_features(vdev))
> return -EINVAL;
>
> + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> + * not the former.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> +
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> int mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
>
We check feature dependency and fail the probe in
virtnet_validate_features().
Is it more straightforward to fail the probe there when
CTRL_GUEST_OFFLOADS was set but CTRL_VQ wasn't?
Thanks
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-24 2:49 ` Jason Wang
@ 2020-01-05 11:16 ` Michael S. Tsirkin
0 siblings, 0 replies; 19+ messages in thread
From: Michael S. Tsirkin @ 2020-01-05 11:16 UTC (permalink / raw)
To: Jason Wang
Cc: Alistair Delva, Willem de Bruijn, LKML, David S. Miller,
virtualization, Network Development
On Tue, Dec 24, 2019 at 10:49:13AM +0800, Jason Wang wrote:
>
> On 2019/12/24 上午4:21, Alistair Delva wrote:
> > On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > > <willemdebruijn.kernel@gmail.com> wrote:
> > > > 00fffe0ff0 DR7: 0000000000000400
> > > > > > Call Trace:
> > > > > > ? preempt_count_add+0x58/0xb0
> > > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > > ? __wake_up+0x70/0x190
> > > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > > __netdev_update_features+0x271/0x980
> > > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > > dev_disable_lro+0x2b/0x190
> > > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > > proc_sys_write+0xf/0x20
> > > > > > __vfs_write+0x3e/0x190
> > > > > > ? __sb_start_write+0x6d/0xd0
> > > > > > vfs_write+0xd3/0x190
> > > > > > ksys_write+0x68/0xd0
> > > > > > __ia32_sys_write+0x14/0x20
> > > > > > do_fast_syscall_32+0x86/0xe0
> > > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > > >
> > > > > > A similar crash will likely trigger when enabling XDP.
> > > > > >
> > > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > > ---
> > > > > >
> > > > > > Lightly tested.
> > > > > >
> > > > > > Alistair, could you please test and confirm that this resolves the
> > > > > > crash for you?
> > > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > > going through the same path and crashing in the same way.
> > > > >
> > > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > > dev->features |= NETIF_F_LRO;
> > > > >
> > > > > It sounds like this patch is fixing something slightly differently to
> > > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > > crash.
> > > >
> > > > Interesting. It's surprising that it is trying to configure a flag
> > > > that is not configurable, i.e., absent from dev->hw_features
> > > > after Michael's change.
> > > >
> > > > > So either we need to ensure NETIF_F_LRO is never set, or
> > > > LRO might be available, just not configurable. Indeed this was what I
> > > > observed in the past.
> > > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > > I guess is a reasonable assumption, just not necessarily the case in
> > > virtio_net.
> > >
> > > So I think we need both patches. Correctly mark the feature as fixed
> > > by removing from dev->hw_features and also ignore the request from
> > > dev_disable_lro, which does not check for this.
> > Something like this maybe:
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 4d7d5434cc5d..0556f42b0fb5 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> > u64 offloads;
> > int err;
> >
> > + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> > + return 0;
> > +
> > if ((dev->features ^ features) & NETIF_F_LRO) {
> > if (vi->xdp_queue_pairs)
> > return -EBUSY;
> > @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> > if (!virtnet_validate_features(vdev))
> > return -EINVAL;
> >
> > + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> > + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> > + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> > + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> > + * not the former.
> > + */
> > + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> > + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> > +
> > if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> > int mtu = virtio_cread16(vdev,
> > offsetof(struct virtio_net_config,
> >
>
> We check feature dependency and fail the probe in
> virtnet_validate_features().
>
> Is it more straightforward to fail the probe there when CTRL_GUEST_OFFLOADS
> was set but CTRL_VQ wasn't?
>
> Thanks
Expanding on what the comment above says, we can't fail probe
in this configuration without breaking the driver for
spec compliant devices.
--
MST
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
@ 2020-01-05 11:16 ` Michael S. Tsirkin
0 siblings, 0 replies; 19+ messages in thread
From: Michael S. Tsirkin @ 2020-01-05 11:16 UTC (permalink / raw)
To: Jason Wang
Cc: Alistair Delva, Willem de Bruijn, Network Development, LKML,
virtualization, David S. Miller
On Tue, Dec 24, 2019 at 10:49:13AM +0800, Jason Wang wrote:
>
> On 2019/12/24 上午4:21, Alistair Delva wrote:
> > On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > > <willemdebruijn.kernel@gmail.com> wrote:
> > > > 00fffe0ff0 DR7: 0000000000000400
> > > > > > Call Trace:
> > > > > > ? preempt_count_add+0x58/0xb0
> > > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > > ? __wake_up+0x70/0x190
> > > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > > __netdev_update_features+0x271/0x980
> > > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > > dev_disable_lro+0x2b/0x190
> > > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > > proc_sys_write+0xf/0x20
> > > > > > __vfs_write+0x3e/0x190
> > > > > > ? __sb_start_write+0x6d/0xd0
> > > > > > vfs_write+0xd3/0x190
> > > > > > ksys_write+0x68/0xd0
> > > > > > __ia32_sys_write+0x14/0x20
> > > > > > do_fast_syscall_32+0x86/0xe0
> > > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > > >
> > > > > > A similar crash will likely trigger when enabling XDP.
> > > > > >
> > > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > > ---
> > > > > >
> > > > > > Lightly tested.
> > > > > >
> > > > > > Alistair, could you please test and confirm that this resolves the
> > > > > > crash for you?
> > > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > > going through the same path and crashing in the same way.
> > > > >
> > > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > > dev->features |= NETIF_F_LRO;
> > > > >
> > > > > It sounds like this patch is fixing something slightly differently to
> > > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > > crash.
> > > >
> > > > Interesting. It's surprising that it is trying to configure a flag
> > > > that is not configurable, i.e., absent from dev->hw_features
> > > > after Michael's change.
> > > >
> > > > > So either we need to ensure NETIF_F_LRO is never set, or
> > > > LRO might be available, just not configurable. Indeed this was what I
> > > > observed in the past.
> > > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > > I guess is a reasonable assumption, just not necessarily the case in
> > > virtio_net.
> > >
> > > So I think we need both patches. Correctly mark the feature as fixed
> > > by removing from dev->hw_features and also ignore the request from
> > > dev_disable_lro, which does not check for this.
> > Something like this maybe:
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 4d7d5434cc5d..0556f42b0fb5 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> > u64 offloads;
> > int err;
> >
> > + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> > + return 0;
> > +
> > if ((dev->features ^ features) & NETIF_F_LRO) {
> > if (vi->xdp_queue_pairs)
> > return -EBUSY;
> > @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> > if (!virtnet_validate_features(vdev))
> > return -EINVAL;
> >
> > + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> > + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> > + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> > + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> > + * not the former.
> > + */
> > + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> > + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> > +
> > if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> > int mtu = virtio_cread16(vdev,
> > offsetof(struct virtio_net_config,
> >
>
> We check feature dependency and fail the probe in
> virtnet_validate_features().
>
> Is it more straightforward to fail the probe there when CTRL_GUEST_OFFLOADS
> was set but CTRL_VQ wasn't?
>
> Thanks
Expanding on what the comment above says, we can't fail probe
in this configuration without breaking the driver for
spec compliant devices.
--
MST
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-23 20:21 ` Alistair Delva
2019-12-24 2:49 ` Jason Wang
@ 2019-12-24 2:49 ` Jason Wang
2019-12-25 16:02 ` Willem de Bruijn
` (3 subsequent siblings)
5 siblings, 0 replies; 19+ messages in thread
From: Jason Wang @ 2019-12-24 2:49 UTC (permalink / raw)
To: Alistair Delva, Willem de Bruijn
Cc: Network Development, David S. Miller, virtualization, LKML,
Michael S. Tsirkin
On 2019/12/24 上午4:21, Alistair Delva wrote:
> On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> <willemdebruijn.kernel@gmail.com> wrote:
>> On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
>> <willemdebruijn.kernel@gmail.com> wrote:
>>> 00fffe0ff0 DR7: 0000000000000400
>>>>> Call Trace:
>>>>> ? preempt_count_add+0x58/0xb0
>>>>> ? _raw_spin_lock_irqsave+0x36/0x70
>>>>> ? _raw_spin_unlock_irqrestore+0x1a/0x40
>>>>> ? __wake_up+0x70/0x190
>>>>> virtnet_set_features+0x90/0xf0 [virtio_net]
>>>>> __netdev_update_features+0x271/0x980
>>>>> ? nlmsg_notify+0x5b/0xa0
>>>>> dev_disable_lro+0x2b/0x190
>>>>> ? inet_netconf_notify_devconf+0xe2/0x120
>>>>> devinet_sysctl_forward+0x176/0x1e0
>>>>> proc_sys_call_handler+0x1f0/0x250
>>>>> proc_sys_write+0xf/0x20
>>>>> __vfs_write+0x3e/0x190
>>>>> ? __sb_start_write+0x6d/0xd0
>>>>> vfs_write+0xd3/0x190
>>>>> ksys_write+0x68/0xd0
>>>>> __ia32_sys_write+0x14/0x20
>>>>> do_fast_syscall_32+0x86/0xe0
>>>>> entry_SYSENTER_compat+0x7c/0x8e
>>>>>
>>>>> A similar crash will likely trigger when enabling XDP.
>>>>>
>>>>> Reported-by: Alistair Delva <adelva@google.com>
>>>>> Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
>>>>> Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
>>>>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>>>>> ---
>>>>>
>>>>> Lightly tested.
>>>>>
>>>>> Alistair, could you please test and confirm that this resolves the
>>>>> crash for you?
>>>> This patch doesn't work. The reason is that NETIF_F_LRO is also turned
>>>> on by TSO4/TSO6, which your patch didn't check for. So it ends up
>>>> going through the same path and crashing in the same way.
>>>>
>>>> if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>>>> virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
>>>> dev->features |= NETIF_F_LRO;
>>>>
>>>> It sounds like this patch is fixing something slightly differently to
>>>> my patch fixed. virtnet_set_features() doesn't care about
>>>> GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
>>>> is zero, it will call virtnet_set_guest_offloads(), which triggers the
>>>> crash.
>>>
>>> Interesting. It's surprising that it is trying to configure a flag
>>> that is not configurable, i.e., absent from dev->hw_features
>>> after Michael's change.
>>>
>>>> So either we need to ensure NETIF_F_LRO is never set, or
>>> LRO might be available, just not configurable. Indeed this was what I
>>> observed in the past.
>> dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
>> I guess is a reasonable assumption, just not necessarily the case in
>> virtio_net.
>>
>> So I think we need both patches. Correctly mark the feature as fixed
>> by removing from dev->hw_features and also ignore the request from
>> dev_disable_lro, which does not check for this.
> Something like this maybe:
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d7d5434cc5d..0556f42b0fb5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> u64 offloads;
> int err;
>
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> + return 0;
> +
> if ((dev->features ^ features) & NETIF_F_LRO) {
> if (vi->xdp_queue_pairs)
> return -EBUSY;
> @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> if (!virtnet_validate_features(vdev))
> return -EINVAL;
>
> + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> + * not the former.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> +
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> int mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
>
We check feature dependency and fail the probe in
virtnet_validate_features().
Is it more straightforward to fail the probe there when
CTRL_GUEST_OFFLOADS was set but CTRL_VQ wasn't?
Thanks
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-23 20:21 ` Alistair Delva
2019-12-24 2:49 ` Jason Wang
2019-12-24 2:49 ` Jason Wang
@ 2019-12-25 16:02 ` Willem de Bruijn
2019-12-25 16:02 ` Willem de Bruijn
` (2 subsequent siblings)
5 siblings, 0 replies; 19+ messages in thread
From: Willem de Bruijn @ 2019-12-25 16:02 UTC (permalink / raw)
To: Alistair Delva
Cc: Willem de Bruijn, Michael S. Tsirkin, Network Development, LKML,
virtualization, David S. Miller
On Mon, Dec 23, 2019 at 3:22 PM Alistair Delva <adelva@google.com> wrote:
>
> On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> <willemdebruijn.kernel@gmail.com> wrote:
> >
> > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > >
> > > 00fffe0ff0 DR7: 0000000000000400
> > > > > Call Trace:
> > > > > ? preempt_count_add+0x58/0xb0
> > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > ? __wake_up+0x70/0x190
> > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > __netdev_update_features+0x271/0x980
> > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > dev_disable_lro+0x2b/0x190
> > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > proc_sys_write+0xf/0x20
> > > > > __vfs_write+0x3e/0x190
> > > > > ? __sb_start_write+0x6d/0xd0
> > > > > vfs_write+0xd3/0x190
> > > > > ksys_write+0x68/0xd0
> > > > > __ia32_sys_write+0x14/0x20
> > > > > do_fast_syscall_32+0x86/0xe0
> > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > >
> > > > > A similar crash will likely trigger when enabling XDP.
> > > > >
> > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > ---
> > > > >
> > > > > Lightly tested.
> > > > >
> > > > > Alistair, could you please test and confirm that this resolves the
> > > > > crash for you?
> > > >
> > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > going through the same path and crashing in the same way.
> > > >
> > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > dev->features |= NETIF_F_LRO;
> > > >
> > > > It sounds like this patch is fixing something slightly differently to
> > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > crash.
> > >
> > >
> > > Interesting. It's surprising that it is trying to configure a flag
> > > that is not configurable, i.e., absent from dev->hw_features
> > > after Michael's change.
> > >
> > > > So either we need to ensure NETIF_F_LRO is never set, or
> > >
> > > LRO might be available, just not configurable. Indeed this was what I
> > > observed in the past.
> >
> > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > I guess is a reasonable assumption, just not necessarily the case in
> > virtio_net.
> >
> > So I think we need both patches. Correctly mark the feature as fixed
> > by removing from dev->hw_features and also ignore the request from
> > dev_disable_lro, which does not check for this.
>
> Something like this maybe:
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d7d5434cc5d..0556f42b0fb5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> u64 offloads;
> int err;
>
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> + return 0;
> +
> if ((dev->features ^ features) & NETIF_F_LRO) {
> if (vi->xdp_queue_pairs)
> return -EBUSY;
> @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> if (!virtnet_validate_features(vdev))
> return -EINVAL;
>
> + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> + * not the former.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> +
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> int mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
I think we need three separate patches.
- disable guest offloads if VQ is absent
- remove LRO from hw_features if guest offloads are absent
This should fix the ethtool path. But there is a separate path to
disable LRO through dev_disable_lro (from bond enslave, xdp install,
sysctl -n net.ipv.ip_forward=1, ..) that assumes LRO is always
configurable. So we cannot work around needing a patch to
virtset_set_features.
After a long detour, I think your original submission is fine for
that.
Perhaps with a comment in the commit that it is needed even
if the feature is absent from hw_features for dev_disable_lro.
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-23 20:21 ` Alistair Delva
` (2 preceding siblings ...)
2019-12-25 16:02 ` Willem de Bruijn
@ 2019-12-25 16:02 ` Willem de Bruijn
2019-12-26 19:12 ` Alistair Delva
2020-01-05 13:13 ` Michael S. Tsirkin
2020-01-05 13:13 ` Michael S. Tsirkin
5 siblings, 1 reply; 19+ messages in thread
From: Willem de Bruijn @ 2019-12-25 16:02 UTC (permalink / raw)
To: Alistair Delva
Cc: Willem de Bruijn, Michael S. Tsirkin, LKML, Jason Wang,
David S. Miller, virtualization, Network Development
On Mon, Dec 23, 2019 at 3:22 PM Alistair Delva <adelva@google.com> wrote:
>
> On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> <willemdebruijn.kernel@gmail.com> wrote:
> >
> > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > >
> > > 00fffe0ff0 DR7: 0000000000000400
> > > > > Call Trace:
> > > > > ? preempt_count_add+0x58/0xb0
> > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > ? __wake_up+0x70/0x190
> > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > __netdev_update_features+0x271/0x980
> > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > dev_disable_lro+0x2b/0x190
> > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > proc_sys_write+0xf/0x20
> > > > > __vfs_write+0x3e/0x190
> > > > > ? __sb_start_write+0x6d/0xd0
> > > > > vfs_write+0xd3/0x190
> > > > > ksys_write+0x68/0xd0
> > > > > __ia32_sys_write+0x14/0x20
> > > > > do_fast_syscall_32+0x86/0xe0
> > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > >
> > > > > A similar crash will likely trigger when enabling XDP.
> > > > >
> > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > ---
> > > > >
> > > > > Lightly tested.
> > > > >
> > > > > Alistair, could you please test and confirm that this resolves the
> > > > > crash for you?
> > > >
> > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > going through the same path and crashing in the same way.
> > > >
> > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > dev->features |= NETIF_F_LRO;
> > > >
> > > > It sounds like this patch is fixing something slightly differently to
> > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > crash.
> > >
> > >
> > > Interesting. It's surprising that it is trying to configure a flag
> > > that is not configurable, i.e., absent from dev->hw_features
> > > after Michael's change.
> > >
> > > > So either we need to ensure NETIF_F_LRO is never set, or
> > >
> > > LRO might be available, just not configurable. Indeed this was what I
> > > observed in the past.
> >
> > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > I guess is a reasonable assumption, just not necessarily the case in
> > virtio_net.
> >
> > So I think we need both patches. Correctly mark the feature as fixed
> > by removing from dev->hw_features and also ignore the request from
> > dev_disable_lro, which does not check for this.
>
> Something like this maybe:
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d7d5434cc5d..0556f42b0fb5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> u64 offloads;
> int err;
>
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> + return 0;
> +
> if ((dev->features ^ features) & NETIF_F_LRO) {
> if (vi->xdp_queue_pairs)
> return -EBUSY;
> @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> if (!virtnet_validate_features(vdev))
> return -EINVAL;
>
> + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> + * not the former.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> +
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> int mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
I think we need three separate patches.
- disable guest offloads if VQ is absent
- remove LRO from hw_features if guest offloads are absent
This should fix the ethtool path. But there is a separate path to
disable LRO through dev_disable_lro (from bond enslave, xdp install,
sysctl -n net.ipv.ip_forward=1, ..) that assumes LRO is always
configurable. So we cannot work around needing a patch to
virtset_set_features.
After a long detour, I think your original submission is fine for
that.
Perhaps with a comment in the commit that it is needed even
if the feature is absent from hw_features for dev_disable_lro.
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-25 16:02 ` Willem de Bruijn
@ 2019-12-26 19:12 ` Alistair Delva
0 siblings, 0 replies; 19+ messages in thread
From: Alistair Delva @ 2019-12-26 19:12 UTC (permalink / raw)
To: Willem de Bruijn
Cc: Michael S. Tsirkin, LKML, Jason Wang, David S. Miller,
virtualization, Network Development
On Wed, Dec 25, 2019 at 8:02 AM Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
>
> On Mon, Dec 23, 2019 at 3:22 PM Alistair Delva <adelva@google.com> wrote:
> >
> > On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > >
> > > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > > <willemdebruijn.kernel@gmail.com> wrote:
> > > >
> > > > 00fffe0ff0 DR7: 0000000000000400
> > > > > > Call Trace:
> > > > > > ? preempt_count_add+0x58/0xb0
> > > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > > ? __wake_up+0x70/0x190
> > > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > > __netdev_update_features+0x271/0x980
> > > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > > dev_disable_lro+0x2b/0x190
> > > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > > proc_sys_write+0xf/0x20
> > > > > > __vfs_write+0x3e/0x190
> > > > > > ? __sb_start_write+0x6d/0xd0
> > > > > > vfs_write+0xd3/0x190
> > > > > > ksys_write+0x68/0xd0
> > > > > > __ia32_sys_write+0x14/0x20
> > > > > > do_fast_syscall_32+0x86/0xe0
> > > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > > >
> > > > > > A similar crash will likely trigger when enabling XDP.
> > > > > >
> > > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > > ---
> > > > > >
> > > > > > Lightly tested.
> > > > > >
> > > > > > Alistair, could you please test and confirm that this resolves the
> > > > > > crash for you?
> > > > >
> > > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > > going through the same path and crashing in the same way.
> > > > >
> > > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > > dev->features |= NETIF_F_LRO;
> > > > >
> > > > > It sounds like this patch is fixing something slightly differently to
> > > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > > crash.
> > > >
> > > >
> > > > Interesting. It's surprising that it is trying to configure a flag
> > > > that is not configurable, i.e., absent from dev->hw_features
> > > > after Michael's change.
> > > >
> > > > > So either we need to ensure NETIF_F_LRO is never set, or
> > > >
> > > > LRO might be available, just not configurable. Indeed this was what I
> > > > observed in the past.
> > >
> > > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > > I guess is a reasonable assumption, just not necessarily the case in
> > > virtio_net.
> > >
> > > So I think we need both patches. Correctly mark the feature as fixed
> > > by removing from dev->hw_features and also ignore the request from
> > > dev_disable_lro, which does not check for this.
> >
> > Something like this maybe:
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 4d7d5434cc5d..0556f42b0fb5 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> > u64 offloads;
> > int err;
> >
> > + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> > + return 0;
> > +
> > if ((dev->features ^ features) & NETIF_F_LRO) {
> > if (vi->xdp_queue_pairs)
> > return -EBUSY;
> > @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> > if (!virtnet_validate_features(vdev))
> > return -EINVAL;
> >
> > + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> > + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> > + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> > + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> > + * not the former.
> > + */
> > + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> > + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> > +
> > if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> > int mtu = virtio_cread16(vdev,
> > offsetof(struct virtio_net_config,
>
> I think we need three separate patches.
>
> - disable guest offloads if VQ is absent
> - remove LRO from hw_features if guest offloads are absent
>
> This should fix the ethtool path. But there is a separate path to
> disable LRO through dev_disable_lro (from bond enslave, xdp install,
> sysctl -n net.ipv.ip_forward=1, ..) that assumes LRO is always
> configurable. So we cannot work around needing a patch to
> virtset_set_features.
>
> After a long detour, I think your original submission is fine for
> that.
Alright. Knowing all the use cases now, and if nobody beats me to it,
I'll resubmit this as a series which fixes the three paths.
> Perhaps with a comment in the commit that it is needed even
> if the feature is absent from hw_features for dev_disable_lro.
Ack.
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-23 20:21 ` Alistair Delva
` (3 preceding siblings ...)
2019-12-25 16:02 ` Willem de Bruijn
@ 2020-01-05 13:13 ` Michael S. Tsirkin
2020-01-05 13:13 ` Michael S. Tsirkin
5 siblings, 0 replies; 19+ messages in thread
From: Michael S. Tsirkin @ 2020-01-05 13:13 UTC (permalink / raw)
To: Alistair Delva
Cc: Willem de Bruijn, LKML, Jason Wang, David S. Miller,
virtualization, Network Development
On Mon, Dec 23, 2019 at 12:21:56PM -0800, Alistair Delva wrote:
> On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> <willemdebruijn.kernel@gmail.com> wrote:
> >
> > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > >
> > > 00fffe0ff0 DR7: 0000000000000400
> > > > > Call Trace:
> > > > > ? preempt_count_add+0x58/0xb0
> > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > ? __wake_up+0x70/0x190
> > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > __netdev_update_features+0x271/0x980
> > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > dev_disable_lro+0x2b/0x190
> > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > proc_sys_write+0xf/0x20
> > > > > __vfs_write+0x3e/0x190
> > > > > ? __sb_start_write+0x6d/0xd0
> > > > > vfs_write+0xd3/0x190
> > > > > ksys_write+0x68/0xd0
> > > > > __ia32_sys_write+0x14/0x20
> > > > > do_fast_syscall_32+0x86/0xe0
> > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > >
> > > > > A similar crash will likely trigger when enabling XDP.
> > > > >
> > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > ---
> > > > >
> > > > > Lightly tested.
> > > > >
> > > > > Alistair, could you please test and confirm that this resolves the
> > > > > crash for you?
> > > >
> > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > going through the same path and crashing in the same way.
> > > >
> > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > dev->features |= NETIF_F_LRO;
> > > >
> > > > It sounds like this patch is fixing something slightly differently to
> > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > crash.
> > >
> > >
> > > Interesting. It's surprising that it is trying to configure a flag
> > > that is not configurable, i.e., absent from dev->hw_features
> > > after Michael's change.
> > >
> > > > So either we need to ensure NETIF_F_LRO is never set, or
> > >
> > > LRO might be available, just not configurable. Indeed this was what I
> > > observed in the past.
> >
> > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > I guess is a reasonable assumption, just not necessarily the case in
> > virtio_net.
> >
> > So I think we need both patches. Correctly mark the feature as fixed
> > by removing from dev->hw_features and also ignore the request from
> > dev_disable_lro, which does not check for this.
>
> Something like this maybe:
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d7d5434cc5d..0556f42b0fb5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> u64 offloads;
> int err;
>
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> + return 0;
> +
> if ((dev->features ^ features) & NETIF_F_LRO) {
> if (vi->xdp_queue_pairs)
> return -EBUSY;
Should this return error here?
> @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> if (!virtnet_validate_features(vdev))
> return -EINVAL;
>
> + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> + * not the former.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> +
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> int mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
This is just my
virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
right?
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH net] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
2019-12-23 20:21 ` Alistair Delva
` (4 preceding siblings ...)
2020-01-05 13:13 ` Michael S. Tsirkin
@ 2020-01-05 13:13 ` Michael S. Tsirkin
5 siblings, 0 replies; 19+ messages in thread
From: Michael S. Tsirkin @ 2020-01-05 13:13 UTC (permalink / raw)
To: Alistair Delva
Cc: Willem de Bruijn, Network Development, LKML, virtualization,
David S. Miller
On Mon, Dec 23, 2019 at 12:21:56PM -0800, Alistair Delva wrote:
> On Mon, Dec 23, 2019 at 12:12 PM Willem de Bruijn
> <willemdebruijn.kernel@gmail.com> wrote:
> >
> > On Mon, Dec 23, 2019 at 2:56 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > >
> > > 00fffe0ff0 DR7: 0000000000000400
> > > > > Call Trace:
> > > > > ? preempt_count_add+0x58/0xb0
> > > > > ? _raw_spin_lock_irqsave+0x36/0x70
> > > > > ? _raw_spin_unlock_irqrestore+0x1a/0x40
> > > > > ? __wake_up+0x70/0x190
> > > > > virtnet_set_features+0x90/0xf0 [virtio_net]
> > > > > __netdev_update_features+0x271/0x980
> > > > > ? nlmsg_notify+0x5b/0xa0
> > > > > dev_disable_lro+0x2b/0x190
> > > > > ? inet_netconf_notify_devconf+0xe2/0x120
> > > > > devinet_sysctl_forward+0x176/0x1e0
> > > > > proc_sys_call_handler+0x1f0/0x250
> > > > > proc_sys_write+0xf/0x20
> > > > > __vfs_write+0x3e/0x190
> > > > > ? __sb_start_write+0x6d/0xd0
> > > > > vfs_write+0xd3/0x190
> > > > > ksys_write+0x68/0xd0
> > > > > __ia32_sys_write+0x14/0x20
> > > > > do_fast_syscall_32+0x86/0xe0
> > > > > entry_SYSENTER_compat+0x7c/0x8e
> > > > >
> > > > > A similar crash will likely trigger when enabling XDP.
> > > > >
> > > > > Reported-by: Alistair Delva <adelva@google.com>
> > > > > Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> > > > > Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > > ---
> > > > >
> > > > > Lightly tested.
> > > > >
> > > > > Alistair, could you please test and confirm that this resolves the
> > > > > crash for you?
> > > >
> > > > This patch doesn't work. The reason is that NETIF_F_LRO is also turned
> > > > on by TSO4/TSO6, which your patch didn't check for. So it ends up
> > > > going through the same path and crashing in the same way.
> > > >
> > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > > virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
> > > > dev->features |= NETIF_F_LRO;
> > > >
> > > > It sounds like this patch is fixing something slightly differently to
> > > > my patch fixed. virtnet_set_features() doesn't care about
> > > > GUEST_OFFLOADS, it only tests against NETIF_F_LRO. Even if "offloads"
> > > > is zero, it will call virtnet_set_guest_offloads(), which triggers the
> > > > crash.
> > >
> > >
> > > Interesting. It's surprising that it is trying to configure a flag
> > > that is not configurable, i.e., absent from dev->hw_features
> > > after Michael's change.
> > >
> > > > So either we need to ensure NETIF_F_LRO is never set, or
> > >
> > > LRO might be available, just not configurable. Indeed this was what I
> > > observed in the past.
> >
> > dev_disable_lro expects that NETIF_F_LRO is always configurable. Which
> > I guess is a reasonable assumption, just not necessarily the case in
> > virtio_net.
> >
> > So I think we need both patches. Correctly mark the feature as fixed
> > by removing from dev->hw_features and also ignore the request from
> > dev_disable_lro, which does not check for this.
>
> Something like this maybe:
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4d7d5434cc5d..0556f42b0fb5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2560,6 +2560,9 @@ static int virtnet_set_features(struct net_device *dev,
> u64 offloads;
> int err;
>
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
> + return 0;
> +
> if ((dev->features ^ features) & NETIF_F_LRO) {
> if (vi->xdp_queue_pairs)
> return -EBUSY;
Should this return error here?
> @@ -2971,6 +2974,15 @@ static int virtnet_validate(struct virtio_device *vdev)
> if (!virtnet_validate_features(vdev))
> return -EINVAL;
>
> + /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
> + * VIRTIO_NET_F_CTRL_VQ. However the virtio spec does not
> + * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
> + * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
> + * not the former.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
> +
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> int mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
This is just my
virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
right?
^ permalink raw reply [flat|nested] 19+ messages in thread