Re: [Qemu-devel] [PATCH qemu v2] vfio/spapr: Allow fallback to SPAPR TCE IOMMU v1

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Dec 12, 2017 at 04:16:19PM +1100, Alexey Kardashevskiy wrote:
> The vfio_iommu_spapr_tce driver advertises kernel's support for
> v1 and v2 IOMMU support, however it is not always possible to use
> the requested IOMMU type. For example, a pseries host platform does not
> support dynamic DMA windows so v2 cannot initialize and QEMU fails to
> start.
> 
> This adds a fallback to the v1 IOMMU if v2 cannot be used.
> 
> Fixes: 318f67ce1371 "vfio: spapr: Add DMA memory preregistering (SPAPR IOMMU v2)"
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Alex, will you take this through your tree, or should I take it
through mine?

> ---
> Changes:
> v2:
> * updated commit log
> 
> ---
>  hw/vfio/common.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 7b2924c..cd81cc9 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -1040,6 +1040,11 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
>              v2 ? VFIO_SPAPR_TCE_v2_IOMMU : VFIO_SPAPR_TCE_IOMMU;
>          ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
>          if (ret) {
> +            container->iommu_type = VFIO_SPAPR_TCE_IOMMU;
> +            v2 = false;
> +            ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
> +        }
> +        if (ret) {
>              error_setg_errno(errp, errno, "failed to set iommu for container");
>              ret = -errno;
>              goto free_container_exit;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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