Yi,
On 3/30/20 6:24 AM, Liu Yi L wrote:
> VFIO needs to check VFIO_TYPE1_NESTING_IOMMU support with Kernel before
> further using it. e.g. requires to check IOMMU UAPI version.
>
> Cc: Kevin Tian <[email protected]>
> Cc: Jacob Pan <[email protected]>
> Cc: Peter Xu <[email protected]>
> Cc: Eric Auger <[email protected]>
> Cc: Yi Sun <[email protected]>
> Cc: David Gibson <[email protected]>
> Cc: Alex Williamson <[email protected]>
> Signed-off-by: Liu Yi L <[email protected]>
> Signed-off-by: Yi Sun <[email protected]>
> ---
> hw/vfio/common.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 0b3593b..c276732 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -1157,12 +1157,21 @@ static void vfio_put_address_space(VFIOAddressSpace
> *space)
> static int vfio_get_iommu_type(VFIOContainer *container,
> Error **errp)
> {
> - int iommu_types[] = { VFIO_TYPE1v2_IOMMU, VFIO_TYPE1_IOMMU,
> + int iommu_types[] = { VFIO_TYPE1_NESTING_IOMMU,
> + VFIO_TYPE1v2_IOMMU, VFIO_TYPE1_IOMMU,
> VFIO_SPAPR_TCE_v2_IOMMU, VFIO_SPAPR_TCE_IOMMU };
> - int i;
> + int i, version;
>
> for (i = 0; i < ARRAY_SIZE(iommu_types); i++) {
> if (ioctl(container->fd, VFIO_CHECK_EXTENSION, iommu_types[i])) {
> + if (iommu_types[i] == VFIO_TYPE1_NESTING_IOMMU) {
> + version = ioctl(container->fd, VFIO_CHECK_EXTENSION,
> + VFIO_NESTING_IOMMU_UAPI);
> + if (version < IOMMU_UAPI_VERSION) {
> + info_report("IOMMU UAPI incompatible for nesting");
> + continue;
> + }
> + }
This means that by default VFIO_TYPE1_NESTING_IOMMU wwould be chosen. I
don't think this what we want. On ARM this would mean that for a
standard VFIO assignment without vIOMMU, SL will be used instead of FL.
This may not be harmless.
For instance, in "[RFC v6 09/24] vfio: Force nested if iommu requires
it", I use nested only if I detect we have a vSMMU. Otherwise I keep the
legacy VFIO_TYPE1v2_IOMMU.
Thanks
Eric
> return iommu_types[i];
> }
> }
> @@ -1278,6 +1287,7 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as,
> }
>
> switch (container->iommu_type) {
> + case VFIO_TYPE1_NESTING_IOMMU:
> case VFIO_TYPE1v2_IOMMU:
> case VFIO_TYPE1_IOMMU:
> {
>
