From: Cédric Le Goater <c...@redhat.com> When doing device assignment of a physical device, MSI-X can be enabled with no vectors enabled and this sets the IRQ index to VFIO_PCI_MSIX_IRQ_INDEX. However, when MSI-X is disabled, the IRQ index is left untouched if no vectors are in use. Then, when INTx is enabled, the IRQ index value is considered incompatible (set to MSI-X) and VFIO_DEVICE_SET_IRQS fails. QEMU complains with :
qemu-system-x86_64: vfio 0000:08:00.0: Failed to set up TRIGGER eventfd signaling for interrupt INTX-0: VFIO_DEVICE_SET_IRQS failure: Invalid argument To avoid that, unconditionaly clear the IRQ index when MSI-X is disabled. Buglink: https://issues.redhat.com/browse/RHEL-21293 Fixes: 5ebffa4e87e7 ("vfio/pci: use an invalid fd to enable MSI-X") Cc: Jing Liu <jing2....@intel.com> Cc: Alex Williamson <alex.william...@redhat.com> Reviewed-by: Alex Williamson <alex.william...@redhat.com> Signed-off-by: Cédric Le Goater <c...@redhat.com> (cherry picked from commit d2b668fca5652760b435ce812a743bba03d2f316) Signed-off-by: Michael Tokarev <m...@tls.msk.ru> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index c62c02f7b6..e167bef2ad 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -824,9 +824,11 @@ static void vfio_msix_disable(VFIOPCIDevice *vdev) } } - if (vdev->nr_vectors) { - vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); - } + /* + * Always clear MSI-X IRQ index. A PF device could have enabled + * MSI-X with no vectors. See vfio_msix_enable(). + */ + vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); vfio_msi_disable_common(vdev); vfio_intx_enable(vdev, &err); -- 2.39.2
