Re: [Qemu-devel] [PATCHv2 5/7] spapr_pci: (Mostly) remove spapr-pci-vfio-host-bridge

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 02/29/2016 06:06 PM, David Gibson wrote:
> Now that the regular spapr-pci-host-bridge can handle EEH, there are only
> two things that spapr-pci-vfio-host-bridge does differently:
>      1. automatically sizes its DMA window to match the host IOMMU
>      2. checks if the attached VFIO container is backed by the
>         VFIO_SPAPR_TCE_IOMMU type on the host
>
> (1) is not particularly useful, since the default window used by the
> regular host bridge will work with the host IOMMU configuration on all
> current systems anyway.
>
> Plus, automatically changing guest visible configuration (such as the DMA
> window) based on host settings is generally a bad idea.  It's not
> definitively broken, since spapr-pci-vfio-host-bridge is only supposed to
> support VFIO devices which can't be migrated anyway, but still.
>
> (2) is not really useful, because if a guest tries to configure EEH on a
> different host IOMMU, the first call will fail and that will be that.
>
> It's possible there are scripts or tools out there which expect
> spapr-pci-vfio-host-bridge, so we don't remove it entirely.  This patch
> reduces it to just a stub for backwards compatibility.
>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>




-- 
Alexey