Hey Nicolin,
On Wed, Jul 09, 2025 at 10:59:15PM -0700, Nicolin Chen wrote:
> An impl driver might want to allocate its own type of vIOMMU object or the
> standard IOMMU_VIOMMU_TYPE_ARM_SMMUV3 by setting up its own SW/HW bits, as
> the tegra241-cmdqv driver will add IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV.
>
> Add vsmmu_size/type and vsmmu_init to struct arm_smmu_impl_ops. Prioritize
> them in arm_smmu_get_viommu_size() and arm_vsmmu_init().
>
> Reviewed-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> ---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 5 +++++
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 8 ++++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index c1ced4d4b6d1..6183f212539a 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -16,6 +16,7 @@
> #include <linux/sizes.h>
>
> struct arm_smmu_device;
> +struct arm_vsmmu;
>
> /* MMIO registers */
> #define ARM_SMMU_IDR0 0x0
> @@ -720,6 +721,10 @@ struct arm_smmu_impl_ops {
> int (*init_structures)(struct arm_smmu_device *smmu);
> struct arm_smmu_cmdq *(*get_secondary_cmdq)(
> struct arm_smmu_device *smmu, struct arm_smmu_cmdq_ent *ent);
> + const size_t vsmmu_size;
> + const enum iommu_viommu_type vsmmu_type;
> + int (*vsmmu_init)(struct arm_vsmmu *vsmmu,
> + const struct iommu_user_data *user_data);
It would be nice to avoid adding data members to the ops structure, if
at all possible. The easiest thing would probably be to add a function
for getting the vsmmu size and then pushing the two checks against
'vsmmu_type' down into the impl_ops callbacks so that:
1. If the type is IOMMU_VIOMMU_TYPE_ARM_SMMUV3, we don't bother with
the impl_ops at all in arm_vsmmu_init() and arm_smmu_get_viommu_size()
2. Otherwise, we pass the type into the impl_ops and they can check it
Of course, that can be a patch on top of the series as there's no point
respinning the whole just for this.
Cheers,
Will
