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(). Work around the issue in virtio for now, and let's try to fix all affected pci systems and then we can revert this. Reported-by: Michael Ellerman <[email protected]> Fixes: 71491c54eafa ("virtio_pci: don't try to use intxif pin is zero") Cc: "Angus Chen" <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]> --- drivers/virtio/virtio_pci_common.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c index 4df77eeb4d16..6155ea4e7e4b 100644 --- a/drivers/virtio/virtio_pci_common.c +++ b/drivers/virtio/virtio_pci_common.c @@ -400,6 +400,7 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned int nvqs, struct irq_affinity *desc) { int err; + u8 pin = 0; /* Try MSI-X with one vector per queue. */ err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true, ctx, desc); @@ -409,8 +410,13 @@ 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 pin? If not give up. + * NB: It would seem to be better to use pci_dev->pin - unfortunately + * not all platforms populate it. + */ + pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin); + if (!pin) return err; /* Finally fall back to regular interrupts. */ return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx); -- MST _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
