Hi Alex,
On 05/12/17 22:09, Alex Williamson wrote:
> Commit 8c37faa475f3 ("vfio-pci, ppc64/spapr: Reorder group-to-container
> attaching") moved registration of groups with the vfio-kvm device from
> vfio_get_group() to vfio_connect_container(), but it missed the case
> where a group is attached to an existing container and takes an early
> exit. Perhaps this is a less common case on ppc64/spapr, but on x86
> (without viommu) all groups are connected to the same container and
> thus only the first group gets registered with the vfio-kvm device.
> This becomes a problem if we then hot-unplug the devices associated
> with that first group and we end up with KVM being misinformed about
> any vfio connections that might remain. Fix by including the call to
> vfio_kvm_device_add_group() in this early exit path.
>
> Fixes: 8c37faa475f3 ("vfio-pci, ppc64/spapr: Reorder group-to-container
> attaching")
> Cc: qemu-sta...@nongnu.org # qemu-2.10+
> Signed-off-by: Alex Williamson <alex.william...@redhat.com>
Reviewed-by: Eric Auger <eric.au...@redhat.com>
Tested-by: Eric Auger <eric.au...@redhat.com>
Tested on arm64 Gigabyte HW with hot-detach of the 2 X540T2 PFs
I don't have the "2017-12-06T08:02:07.535373Z qemu-system-aarch64:
Failed to remove group 24 from KVM VFIO device: No such file or
directory" anymore when detaching the second PF.
Thanks
Eric
> ---
>
> This bug also existed in QEMU 2.10, but I think the fix is sufficiently
> obvious (famous last words) to propose for 2.11 at this late date. If
> the first group is hot unplugged then KVM may revert to code emulation
> that assumes no non-coherent DMA is present on some systems. Also for
> KVMGT, if the vGPU is not the first device registered, then the
> notifier to enable linkages to KVM would not be called. Please review.
> Thanks,
>
> Alex
>
> hw/vfio/common.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 7b2924c0ef19..7007878e345e 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -968,6 +968,7 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as,
> if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) {
> group->container = container;
> QLIST_INSERT_HEAD(&container->group_list, group, container_next);
> + vfio_kvm_device_add_group(group);
> return 0;
> }
> }
>
>
