On Fri, Oct 14, 2022 at 12:09:20AM +0000, Angus Chen wrote:
> Hi Mst
>
> > -----Original Message-----
> > From: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > Sent: Thursday, October 13, 2022 6:04 AM
> > To: linux-kernel@xxxxxxxxxxxxxxx
> > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>; Michael Ellerman
> > <mpe@xxxxxxxxxxxxxx>; Angus Chen <angus.chen@xxxxxxxxxxxxxxx>; Jason
> > Wang <jasowang@xxxxxxxxxx>; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > Subject: [PATCH] virtio_pci: use irq to detect interrupt support
> >
> > 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>
> > ---
> >
> > Build tested only - very late here. Angus any chance you could
> > help test this? Thanks!
> I tested the patch ，it work well on x86。Inlcude legacy and modern driver.
> And I tested it on arm server also，and find some problem because of 0.9.5 limitation.
> "platform bug: legacy virtio-pci must not be used with RAM above 0x%llxGB\n",
> But the error is not effected by our patch.with or without our patch ,it print the same.
Yes that's a limitation of 0.9.5 - just make a smaller VM to test
legacy.
> And I test modern dirver,it work well also.
> Sorry for the late reply.
Great, thanks a lot!
> >
> > 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
>
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
