On Thu, 25 Jan 2024 15:42:20 +0100 Cédric Le Goater <c...@redhat.com> wrote:
> 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> > Signed-off-by: Cédric Le Goater <c...@redhat.com> > --- > hw/vfio/pci.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c > index > d7fe06715c4b9cde66a68c31aaf405315921b0d6..4fa387f0430d62ca2ba1b5ae5b7037f8f06b33f9 > 100644 > --- a/hw/vfio/pci.c > +++ b/hw/vfio/pci.c > @@ -826,9 +826,11 @@ 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); LGTM, at worst the SET_IRQS ioctl return an errno if we try to disable an unconfigured interrupt index, so seems safe to call unconditionally here. Reviewed-by: Alex Williamson <alex.william...@redhat.com>