Re: [Qemu-devel] [PATCH 4/4] spapr_pci: Allow VFIO devices to work on the normal PCI host bridge

[Thomas Huth <thuth@redhat.com>]

On 30/09/15 05:48, David Gibson wrote:
> The core VFIO infrastructure more or less allows VFIO devices to work
> on any normal guest PCI host bridge (PHB) without extra logic.
> However, the "spapr-pci-host-bridge" device (as opposed to the special
> "spapr-pci-vfio-host-bridge" device) breaks this by using a partially
> KVM accelerated implementation of the guest kernel IOMMU which won't
> work with VFIO devices, without additional kernel support.
> 
> This patch allows VFIO devices to work on the spapr-pci-host-bridge,
> by having it switch off KVM TCE acceleration when a VFIO device is
> added to the PHB (either on startup, or by hotplug).
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  hw/ppc/spapr_pci.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index cb7c351..55fa8db 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -1083,6 +1083,12 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
>      void *fdt = NULL;
>      int fdt_start_offset = 0, fdt_size;
>  
> +    if (object_dynamic_cast(OBJECT(pdev), "vfio-pci")) {
> +        sPAPRTCETable *tcet = spapr_tce_find_by_liobn(phb->dma_liobn);
> +
> +        spapr_tce_set_need_vfio(tcet, true);
> +    }
> +
>      if (dev->hotplugged) {
>          fdt = create_device_tree(&fdt_size);
>          fdt_start_offset = spapr_create_pci_child_dt(phb, pdev, fdt, 0);

Reviewed-by: Thomas Huth <thuth@redhat.com>