Re: [Qemu-devel] [RFC PATCH v2 2/2] VFIO: Clear stale MSIx table during EEH reset

[Alex Williamson <alex.williamson@redhat.com>]

On Mon, 2014-09-01 at 10:53 +1000, Gavin Shan wrote:
> The PCI device MSIx table is cleaned out in hardware after EEH PE
> reset. However, we still hold the stale MSIx entries in QEMU, which
> should be cleared accordingly. Otherwise, we will run into another
> (recursive) EEH error and the PCI devices contained in the PE have
> to be offlined exceptionally.
> 
> The patch clears stale MSIx table before EEH PE reset so that MSIx
> table could be restored properly after EEH PE reset.
> 
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> ---
>  hw/misc/vfio.c | 32 +++++++++++++++++++++++++++++++-
>  1 file changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> index 1a3e7eb..1f55051 100644
> --- a/hw/misc/vfio.c
> +++ b/hw/misc/vfio.c
> @@ -2724,6 +2724,17 @@ static void vfio_disable_interrupts(VFIODevice *vdev)
>      }
>  }
>  
> +static void vfio_disable_and_reset_interrupts(VFIODevice *vdev)
> +{
> +    vfio_disable_interrupts(vdev);
> +
> +    switch (vdev->interrupt) {
> +    case VFIO_INT_MSIX:
> +        msix_reset(&vdev->pdev);
> +        break;
> +    }

This is apparently untested because vdev->interrupt should never be set
to VFIO_INT_MSIX after vfio_disable_interrupts().  Also, you need to
update the normal reset path to call msix_reset() unless it's already
happening via another reset handler.  Thanks,

Alex

> +}
> +
>  static int vfio_setup_msi(VFIODevice *vdev, int pos)
>  {
>      uint16_t ctrl;
> @@ -4442,8 +4453,27 @@ int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
>      switch (req) {
>      case VFIO_CHECK_EXTENSION:
>      case VFIO_IOMMU_SPAPR_TCE_GET_INFO:
> -    case VFIO_EEH_PE_OP:
>          break;
> +    case VFIO_EEH_PE_OP: {
> +        VFIODevice *vdev;
> +        struct vfio_eeh_pe_op *arg = (struct vfio_eeh_pe_op *)param;
> +
> +        switch (arg->op) {
> +        case VFIO_EEH_PE_RESET_HOT:
> +        case VFIO_EEH_PE_RESET_FUNDAMENTAL:
> +            /*
> +             * The MSIx table will be cleaned out by reset. We need
> +             * disable it so that it can be reenabled properly. Also,
> +             * the cached MSIx table should be cleared as it's not
> +             * reflecting the contents in hardware.
> +             */
> +            QLIST_FOREACH(vdev, &group->device_list, next) {
> +                vfio_disable_and_reset_interrupts(vdev);
> +            }
> +        }
> +
> +        break;
> +    }
>      default:
>          /* Return an error on unknown requests */
>          error_report("vfio: unsupported ioctl %X", req);