On Thu, Oct 13, 2022 at 6:04 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> commit 71491c54eafa ("virtio_pci: don't try to use intxif pin is zero")
> breaks virtio_pci on powerpc, when running as a qemu guest.
>
> vp_find_vqs() bails out because pci_dev->pin == 0.
>
> But pci_dev->irq is populated correctly, so vp_find_vqs_intx() would
> succeed if we called it - which is what the code used to do.
>
> This seems to happen because pci_dev->pin is not populated in
> pci_assign_irq().
>
> Which is absolutely a bug in the relevant PCI code, but it
> may also affect other platforms that use of_irq_parse_and_map_pci().
>
> However Linus said:
> The correct way to check for "no irq" doesn't use NO_IRQ at all, it just does
> if (dev->irq) ...
> so let's just check irq and be done with it.
>
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Reported-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Fixes: 71491c54eafa ("virtio_pci: don't try to use intxif pin is zero")
> Cc: "Angus Chen" <angus.chen@xxxxxxxxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
>
> Build tested only - very late here. Angus any chance you could
> help test this? Thanks!
>
> drivers/virtio/virtio_pci_common.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index 4df77eeb4d16..a6c86f916dbd 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -409,8 +409,8 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
> err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false, ctx, desc);
> if (!err)
> return 0;
> - /* Is there an interrupt pin? If not give up. */
> - if (!(to_vp_device(vdev)->pci_dev->pin))
> + /* Is there an interrupt? If not give up. */
> + if (!(to_vp_device(vdev)->pci_dev->irq))
> return err;
> /* Finally fall back to regular interrupts. */
> return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);
> --
> MST
>
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