On Sun, Sep 14, 2014 at 08:23:26PM -0700, Anthony Liguori wrote: > From: Anthony Liguori <[email protected]> > > If MSI-X initialization fails after setting msix_enabled = 1, then > the device is left in an inconsistent state. This would normally > only happen if there was a bug in the device emulation but it still > should be handled correctly.
This might happen if host runs out of resources when trying to map VQs to vectors, so doesn't have to be a bug. But I don't see what the problem is: msix_used_vectors reflects the number of used vectors and msix_enabled is set, thus vp_free_vectors will free all IRQs and then disable MSIX. Where is the inconsistency you speak about? > > Cc: Matt Wilson <[email protected]> > Cc: Rusty Russell <[email protected]> > Cc: Michael Tsirkin <[email protected]> > Signed-off-by: Anthony Liguori <[email protected]> > --- > drivers/virtio/virtio_pci.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c > index 9cbac33..3d2c2a5 100644 > --- a/drivers/virtio/virtio_pci.c > +++ b/drivers/virtio/virtio_pci.c > @@ -357,7 +357,7 @@ static int vp_request_msix_vectors(struct virtio_device > *vdev, int nvectors, > v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR); > if (v == VIRTIO_MSI_NO_VECTOR) { > err = -EBUSY; > - goto error; > + goto error_msix_used; > } > > if (!per_vq_vectors) { > @@ -369,11 +369,15 @@ static int vp_request_msix_vectors(struct virtio_device > *vdev, int nvectors, > vp_vring_interrupt, 0, vp_dev->msix_names[v], > vp_dev); > if (err) > - goto error; > + goto error_msix_used; > ++vp_dev->msix_used_vectors; > } > return 0; > +error_msix_used: > + v = --vp_dev->msix_used_vectors; > + free_irq(vp_dev->msix_entries[v].vector, vp_dev); > error: > + vp_dev->msix_enabled = 0; As far as I can see, if you do this, guest will not call pci_disable_msix thus leaving the device with MSIX enabled. I'm not sure this won't break drivers if they then try to use the device without MSIX, and it definitely seems less elegant than reverting the device to the original state. > vp_free_vectors(vdev); > return err; > } > -- > 1.7.9.5 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
