Virtualization - May 2023 - [PATCH] virtio-vdpa: Fix unchecked call to NULL set_vq_affinity

On Thu, May 04, 2023 at 01:08:54PM -0400, Feng Liu
wrote:
> 
> 
> On 2023-05-04 a.m.9:50, Dragos Tatulea wrote:
> > External email: Use caution opening links or attachments
> > 
> > 
> > The referenced patch calls set_vq_affinity without checking if the op
is
> > valid. This patch adds the check.
> > 
> > Fixes: 3dad56823b53 ("virtio-vdpa: Support interrupt affinity
spreading mechanism")
> > Reviewed-by: Gal Pressman <gal at nvidia.com>
> > Signed-off-by: Dragos Tatulea <dtatulea at nvidia.com>
> > ---
> >   drivers/virtio/virtio_vdpa.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/virtio/virtio_vdpa.c
b/drivers/virtio/virtio_vdpa.c
> > index eb6aee8c06b2..989e2d7184ce 100644
> > --- a/drivers/virtio/virtio_vdpa.c
> > +++ b/drivers/virtio/virtio_vdpa.c
> > @@ -385,7 +385,9 @@ static int virtio_vdpa_find_vqs(struct
virtio_device *vdev, unsigned int nvqs,
> >                          err = PTR_ERR(vqs[i]);
> >                          goto err_setup_vq;
> >                  }
> > -               ops->set_vq_affinity(vdpa, i, &masks[i]);
> > +
> > +               if (ops->set_vq_affinity)
> > +                       ops->set_vq_affinity(vdpa, i,
&masks[i]);
> if ops->set_vq_affinity is NULL, should give an error code to err, and
> return err
Given we ignore return code, hardly seems like a critical thing to do.
Is it really important? affinity is an optimization isn't it?
> >          }
> > 
> >          cb.callback = virtio_vdpa_config_cb;
> > --
> > 2.40.1
> >

On 2023-05-04 p.m.2:51, Michael S. Tsirkin wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Thu, May 04, 2023 at 01:08:54PM -0400, Feng Liu wrote:
>>
>>
>> On 2023-05-04 a.m.9:50, Dragos Tatulea wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> The referenced patch calls set_vq_affinity without checking if the
op is
>>> valid. This patch adds the check.
>>>
>>> Fixes: 3dad56823b53 ("virtio-vdpa: Support interrupt affinity
spreading mechanism")
>>> Reviewed-by: Gal Pressman <gal at nvidia.com>
>>> Signed-off-by: Dragos Tatulea <dtatulea at nvidia.com>
>>> ---
>>>    drivers/virtio/virtio_vdpa.c | 4 +++-
>>>    1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/virtio/virtio_vdpa.c
b/drivers/virtio/virtio_vdpa.c
>>> index eb6aee8c06b2..989e2d7184ce 100644
>>> --- a/drivers/virtio/virtio_vdpa.c
>>> +++ b/drivers/virtio/virtio_vdpa.c
>>> @@ -385,7 +385,9 @@ static int virtio_vdpa_find_vqs(struct
virtio_device *vdev, unsigned int nvqs,
>>>                           err = PTR_ERR(vqs[i]);
>>>                           goto err_setup_vq;
>>>                   }
>>> -               ops->set_vq_affinity(vdpa, i, &masks[i]);
>>> +
>>> +               if (ops->set_vq_affinity)
>>> +                       ops->set_vq_affinity(vdpa, i,
&masks[i]);
>> if ops->set_vq_affinity is NULL, should give an error code to err,
and
>> return err
> 
> Given we ignore return code, hardly seems like a critical thing to do.
> Is it really important? affinity is an optimization isn't it?
> 
Yes, it is an optimization, got it.
>>>           }
>>>
>>>           cb.callback = virtio_vdpa_config_cb;
>>> --
>>> 2.40.1
>>>
>

On Thu, 2023-05-04 at 14:51 -0400, Michael S. Tsirkin
wrote:
> On Thu, May 04, 2023 at 01:08:54PM -0400, Feng Liu wrote:
> > 
> > 
> > On 2023-05-04 a.m.9:50, Dragos Tatulea wrote:
> > > External email: Use caution opening links or attachments
> > > 
> > > 
> > > The referenced patch calls set_vq_affinity without checking if
the op is
> > > valid. This patch adds the check.
> > > 
> > > Fixes: 3dad56823b53 ("virtio-vdpa: Support interrupt
affinity spreading
> > > mechanism")
> > > Reviewed-by: Gal Pressman <gal at nvidia.com>
> > > Signed-off-by: Dragos Tatulea <dtatulea at nvidia.com>
> > > ---
> > > ? drivers/virtio/virtio_vdpa.c | 4 +++-
> > > ? 1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/virtio/virtio_vdpa.c
b/drivers/virtio/virtio_vdpa.c
> > > index eb6aee8c06b2..989e2d7184ce 100644
> > > --- a/drivers/virtio/virtio_vdpa.c
> > > +++ b/drivers/virtio/virtio_vdpa.c
> > > @@ -385,7 +385,9 @@ static int virtio_vdpa_find_vqs(struct
virtio_device
> > > *vdev, unsigned int nvqs,
> > > ???????????????????????? err = PTR_ERR(vqs[i]);
> > > ???????????????????????? goto err_setup_vq;
> > > ???????????????? }
> > > -?????????????? ops->set_vq_affinity(vdpa, i, &masks[i]);
> > > +
> > > +?????????????? if (ops->set_vq_affinity)
> > > +?????????????????????? ops->set_vq_affinity(vdpa, i,
&masks[i]);
> > if ops->set_vq_affinity is NULL, should give an error code to err,
and
> > return err
> 
> Given we ignore return code, hardly seems like a critical thing to do.
> Is it really important? affinity is an optimization isn't it?
> 
> > > 
set_vq_affinity is optional so it's not an error if the op is not
implemented.

Is there anything else that needs to be done for this fix?

Thanks,
Dragos