On Wed, Nov 22, 2017 at 04:15:52PM +1100, Alexey Kardashevskiy wrote: > The vfio_iommu_spapr_tce driver always advertises v1 and v2 IOMMU support, > however PR KVM (a special version of KVM designed to work in > a paravirtualized system; these days used for nested virtualizaion) only > supports the "pseries" platform which does not support v2. Since there is > no way to choose the IOMMU version in QEMU, it fails to start. > > This adds a fallback to the v1 IOMMU if v2 cannot be used. > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
The fallback itself isn't a bad idea, but your commit message contains
several inaccurracies. KVM PR is not particularly designed to work in
a paravirtualized system, and it doesn't only support the pseries
platform (as guest *or* host). It's actually a lot more general than
KVM HV - just slow, not that well tested and missing a number of
features that no-one's bothered to port to it.
> ---
> 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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