Mailing List Archive: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio

[PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device()

Jul 29, 2021, 1:05 AM

Post #1 of 8 (2 views)

The device reset may fail in virtio-vdpa case now, so add checks to
its return value and fail the register_virtio_device().

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
drivers/virtio/virtio.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index a15beb6b593b..8df75425fb43 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -349,7 +349,9 @@ int register_virtio_device(struct virtio_device *dev)

/* We always start by resetting the device, in case a previous
* driver messed it up. This also tests that code path a little. */
- dev->config->reset(dev);
+ err = dev->config->reset(dev);
+ if (err)
+ goto err_reset;

/* Acknowledge that we've seen the device. */
virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
@@ -362,10 +364,13 @@ int register_virtio_device(struct virtio_device *dev)
*/
err = device_add(&dev->dev);
if (err)
- ida_simple_remove(&virtio_index_ida, dev->index);
-out:
- if (err)
- virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+ goto err_add;
+
+ return 0;
+err_add:
+ virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+err_reset:
+ ida_simple_remove(&virtio_index_ida, dev->index);
return err;
}
EXPORT_SYMBOL_GPL(register_virtio_device);
--
2.11.0

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

jasowang at redhat

Aug 3, 2021, 2:15 AM

Post #2 of 8 (2 views)

Permalink

?? 2021/7/29 ????3:34, Xie Yongji ???:
> The device reset may fail in virtio-vdpa case now, so add checks to
> its return value and fail the register_virtio_device().

So the reset() would be called by the driver during remove as well, or
is it sufficient to deal only with the reset during probe?

Thanks

>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> ---
> drivers/virtio/virtio.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index a15beb6b593b..8df75425fb43 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -349,7 +349,9 @@ int register_virtio_device(struct virtio_device *dev)
>
> /* We always start by resetting the device, in case a previous
> * driver messed it up. This also tests that code path a little. */
> - dev->config->reset(dev);
> + err = dev->config->reset(dev);
> + if (err)
> + goto err_reset;
>
> /* Acknowledge that we've seen the device. */
> virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> @@ -362,10 +364,13 @@ int register_virtio_device(struct virtio_device *dev)
> */
> err = device_add(&dev->dev);
> if (err)
> - ida_simple_remove(&virtio_index_ida, dev->index);
> -out:
> - if (err)
> - virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> + goto err_add;
> +
> + return 0;
> +err_add:
> + virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> +err_reset:
> + ida_simple_remove(&virtio_index_ida, dev->index);
> return err;
> }
> EXPORT_SYMBOL_GPL(register_virtio_device);

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

xieyongji at bytedance

Aug 3, 2021, 4:15 AM

Post #3 of 8 (2 views)

Permalink

On Tue, Aug 3, 2021 at 4:09 PM Jason Wang <jasowang@redhat.com> wrote:
>
>
> ? 2021/7/29 ??3:34, Xie Yongji ??:
> > The device reset may fail in virtio-vdpa case now, so add checks to
> > its return value and fail the register_virtio_device().
>
>
> So the reset() would be called by the driver during remove as well, or
> is it sufficient to deal only with the reset during probe?
>

Actually there is no way to handle failure during removal. And it
should be safe with the protection of software IOTLB even if the
reset() fails.

Thanks,
Yongji

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

jasowang at redhat

Aug 4, 2021, 2:15 AM

Post #4 of 8 (2 views)

Permalink

? 2021/8/3 ??5:38, Yongji Xie ??:
> On Tue, Aug 3, 2021 at 4:09 PM Jason Wang <jasowang@redhat.com> wrote:
>>
>> ? 2021/7/29 ??3:34, Xie Yongji ??:
>>> The device reset may fail in virtio-vdpa case now, so add checks to
>>> its return value and fail the register_virtio_device().
>>
>> So the reset() would be called by the driver during remove as well, or
>> is it sufficient to deal only with the reset during probe?
>>
> Actually there is no way to handle failure during removal. And it
> should be safe with the protection of software IOTLB even if the
> reset() fails.
>
> Thanks,
> Yongji

If this is true, does it mean we don't even need to care about reset
failure?

Thanks

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

xieyongji at bytedance

Aug 4, 2021, 2:15 AM

Post #5 of 8 (2 views)

Permalink

On Wed, Aug 4, 2021 at 4:32 PM Jason Wang <jasowang@redhat.com> wrote:
>
>
> ? 2021/8/3 ??5:38, Yongji Xie ??:
> > On Tue, Aug 3, 2021 at 4:09 PM Jason Wang <jasowang@redhat.com> wrote:
> >>
> >> ? 2021/7/29 ??3:34, Xie Yongji ??:
> >>> The device reset may fail in virtio-vdpa case now, so add checks to
> >>> its return value and fail the register_virtio_device().
> >>
> >> So the reset() would be called by the driver during remove as well, or
> >> is it sufficient to deal only with the reset during probe?
> >>
> > Actually there is no way to handle failure during removal. And it
> > should be safe with the protection of software IOTLB even if the
> > reset() fails.
> >
> > Thanks,
> > Yongji
>
>
> If this is true, does it mean we don't even need to care about reset
> failure?
>

But we need to handle the failure in the vhost-vdpa case, isn't it?

Thanks,
Yongji

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

jasowang at redhat

Aug 4, 2021, 2:15 AM

Post #6 of 8 (2 views)

Permalink

? 2021/8/4 ??4:50, Yongji Xie ??:
> On Wed, Aug 4, 2021 at 4:32 PM Jason Wang <jasowang@redhat.com> wrote:
>>
>> ? 2021/8/3 ??5:38, Yongji Xie ??:
>>> On Tue, Aug 3, 2021 at 4:09 PM Jason Wang <jasowang@redhat.com> wrote:
>>>> ? 2021/7/29 ??3:34, Xie Yongji ??:
>>>>> The device reset may fail in virtio-vdpa case now, so add checks to
>>>>> its return value and fail the register_virtio_device().
>>>> So the reset() would be called by the driver during remove as well, or
>>>> is it sufficient to deal only with the reset during probe?
>>>>
>>> Actually there is no way to handle failure during removal. And it
>>> should be safe with the protection of software IOTLB even if the
>>> reset() fails.
>>>
>>> Thanks,
>>> Yongji
>>
>> If this is true, does it mean we don't even need to care about reset
>> failure?
>>
> But we need to handle the failure in the vhost-vdpa case, isn't it?

Yes, but:

- This patch is for virtio not for vhost, if we don't care virtio, we
can avoid the changes
- For vhost, there could be two ways probably:

1) let the set_status to report error
2) require userspace to re-read for status

It looks to me you want to go with 1) and I'm not sure whether or not
it's too late to go with 2).

Thanks

>
> Thanks,
> Yongji
>

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

xieyongji at bytedance

Aug 4, 2021, 2:15 AM

Post #7 of 8 (2 views)

Permalink

On Wed, Aug 4, 2021 at 4:54 PM Jason Wang <jasowang@redhat.com> wrote:
>
>
> ? 2021/8/4 ??4:50, Yongji Xie ??:
> > On Wed, Aug 4, 2021 at 4:32 PM Jason Wang <jasowang@redhat.com> wrote:
> >>
> >> ? 2021/8/3 ??5:38, Yongji Xie ??:
> >>> On Tue, Aug 3, 2021 at 4:09 PM Jason Wang <jasowang@redhat.com> wrote:
> >>>> ? 2021/7/29 ??3:34, Xie Yongji ??:
> >>>>> The device reset may fail in virtio-vdpa case now, so add checks to
> >>>>> its return value and fail the register_virtio_device().
> >>>> So the reset() would be called by the driver during remove as well, or
> >>>> is it sufficient to deal only with the reset during probe?
> >>>>
> >>> Actually there is no way to handle failure during removal. And it
> >>> should be safe with the protection of software IOTLB even if the
> >>> reset() fails.
> >>>
> >>> Thanks,
> >>> Yongji
> >>
> >> If this is true, does it mean we don't even need to care about reset
> >> failure?
> >>
> > But we need to handle the failure in the vhost-vdpa case, isn't it?
>
>
> Yes, but:
>
> - This patch is for virtio not for vhost, if we don't care virtio, we
> can avoid the changes
> - For vhost, there could be two ways probably:
>
> 1) let the set_status to report error
> 2) require userspace to re-read for status
>
> It looks to me you want to go with 1) and I'm not sure whether or not
> it's too late to go with 2).
>

Looks like 2) can't work if reset failure happens in
vhost_vdpa_release() and vhost_vdpa_open().

Thanks,
Yongji

Re: [PATCH v10 10/17] virtio: Handle device reset failure in register_virtio_device() [ In reply to ]

jasowang at redhat

Aug 5, 2021, 12:15 AM

Post #8 of 8 (2 views)

Permalink

? 2021/8/4 ??5:07, Yongji Xie ??:
> On Wed, Aug 4, 2021 at 4:54 PM Jason Wang <jasowang@redhat.com> wrote:
>>
>> ? 2021/8/4 ??4:50, Yongji Xie ??:
>>> On Wed, Aug 4, 2021 at 4:32 PM Jason Wang <jasowang@redhat.com> wrote:
>>>> ? 2021/8/3 ??5:38, Yongji Xie ??:
>>>>> On Tue, Aug 3, 2021 at 4:09 PM Jason Wang <jasowang@redhat.com> wrote:
>>>>>> ? 2021/7/29 ??3:34, Xie Yongji ??:
>>>>>>> The device reset may fail in virtio-vdpa case now, so add checks to
>>>>>>> its return value and fail the register_virtio_device().
>>>>>> So the reset() would be called by the driver during remove as well, or
>>>>>> is it sufficient to deal only with the reset during probe?
>>>>>>
>>>>> Actually there is no way to handle failure during removal. And it
>>>>> should be safe with the protection of software IOTLB even if the
>>>>> reset() fails.
>>>>>
>>>>> Thanks,
>>>>> Yongji
>>>> If this is true, does it mean we don't even need to care about reset
>>>> failure?
>>>>
>>> But we need to handle the failure in the vhost-vdpa case, isn't it?
>>
>> Yes, but:
>>
>> - This patch is for virtio not for vhost, if we don't care virtio, we
>> can avoid the changes
>> - For vhost, there could be two ways probably:
>>
>> 1) let the set_status to report error
>> 2) require userspace to re-read for status
>>
>> It looks to me you want to go with 1) and I'm not sure whether or not
>> it's too late to go with 2).
>>
> Looks like 2) can't work if reset failure happens in
> vhost_vdpa_release() and vhost_vdpa_open().

Yes, you're right.

Thanks

>
> Thanks,
> Yongji
>