Re: [PATCH v1] virtio-pci: Fix legacy device flag setting error in probe

[Feng Liu]

On 2023-07-24 p.m.11:41, Jason Wang wrote:
> External email: Use caution opening links or attachments
>
>
> On Mon, Jul 24, 2023 at 9:14 PM Feng Liu <feliu@xxxxxxxxxx> wrote:
> > On 2023-07-20 p.m.1:14, Michael S. Tsirkin wrote:
> > > External email: Use caution opening links or attachments
> > >
> > >
> > > On Thu, Jul 20, 2023 at 10:27:04AM +0800, Jason Wang wrote:
> > > > On Wed, Jul 19, 2023 at 11:46 PM Feng Liu <feliu@xxxxxxxxxx> wrote:
> > > > > The 'is_legacy' flag is used to differentiate between legacy vs modern
> > > > > device. Currently, it is based on the value of vp_dev->ldev.ioaddr.
> > > > > However, due to the shared memory of the union between struct
> > > > > virtio_pci_legacy_device and struct virtio_pci_modern_device, when
> > > > > virtio_pci_modern_probe modifies the content of struct
> > > > > virtio_pci_modern_device, it affects the content of struct
> > > > > virtio_pci_legacy_device, and ldev.ioaddr is no longer zero, causing
> > > > > the 'is_legacy' flag to be set as true. To resolve issue, when legacy
> > > > > device is probed, mark 'is_legacy' as true, when modern device is
> > > > > probed, keep 'is_legacy' as false.
> > > > >
> > > > > Fixes: 4f0fc22534e3 ("virtio_pci: Optimize virtio_pci_device structure size")
> > > > > Signed-off-by: Feng Liu <feliu@xxxxxxxxxx>
> > > > > Reviewed-by: Parav Pandit <parav@xxxxxxxxxx>
> > > > > Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
> > > > > ---
> > > > >    drivers/virtio/virtio_pci_common.c | 2 --
> > > > >    drivers/virtio/virtio_pci_legacy.c | 1 +
> > > > >    2 files changed, 1 insertion(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > > > > index a6c86f916dbd..c2524a7207cf 100644
> > > > > --- a/drivers/virtio/virtio_pci_common.c
> > > > > +++ b/drivers/virtio/virtio_pci_common.c
> > > > > @@ -557,8 +557,6 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
> > > > >
> > > > >           pci_set_master(pci_dev);
> > > > >
> > > > > -       vp_dev->is_legacy = vp_dev->ldev.ioaddr ? true : false;
> > > > > -
> > > > >           rc = register_virtio_device(&vp_dev->vdev);
> > > > >           reg_dev = vp_dev;
> > > > >           if (rc)
> > > > > diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> > > > > index 2257f1b3d8ae..d9cbb02b35a1 100644
> > > > > --- a/drivers/virtio/virtio_pci_legacy.c
> > > > > +++ b/drivers/virtio/virtio_pci_legacy.c
> > > > > @@ -223,6 +223,7 @@ int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
> > > > >           vp_dev->config_vector = vp_config_vector;
> > > > >           vp_dev->setup_vq = setup_vq;
> > > > >           vp_dev->del_vq = del_vq;
> > > > > +       vp_dev->is_legacy = true;
> > > >
> > > > This seems break force_legacy for modern device:
> > > >
> > > >           if (force_legacy) {
> > > >                   rc = virtio_pci_legacy_probe(vp_dev);
> > > >                   /* Also try modern mode if we can't map BAR0 (no IO space). */
> > > >                   if (rc == -ENODEV || rc == -ENOMEM)
> > > >                           rc = virtio_pci_modern_probe(vp_dev);
> > > >
> > > > Thanks
> > >
> > > don't see the breakage here - can you explain a bit more?
> > Hi, Jason
> >
> > I also think there is no breakage herea and gave an explanation in
> > another email, please have a see.
>
> I think I've made a mistake, the patch should be fine.
>
> > So are there any comments about this bug fix patch? Can this patch pass
> > the review?
>
> Yes.
>
> Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> Thanks

Thanks Jason

> > Thanks
> > Feng
> >
> > > > >           return 0;
> > > > >    }
> > > > > --
> > > > > 2.37.1 (Apple Git-137.1)