From 2145ab513e3b3f910bd4a93abbdfa74fc65dfea4 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 12 Oct 2022 17:58:28 -0400 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(). A PCI core bug? Maybe. However Linus said: I really think that that is basically the only time you should use that 'pci_dev->pin' thing: it basically exists not for "does this device have an IRQ", but for "what is the routing of this irq on this device". and 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 Reported-by: Michael Ellerman Fixes: 71491c54eafa ("virtio_pci: don't try to use intxif pin is zero") Cc: "Angus Chen" Signed-off-by: Michael S. Tsirkin Tested-by: Michael Ellerman Acked-by: Jason Wang Message-Id: <20221012220312.308522-1-mst@redhat.com> --- 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);