[PATCH v2 1/2] iommu/arm-smmu-v3: Do not bother impl_ops if IOMMU_VIOMMU_TYPE_ARM_SMMUV3
Will Deacon
will at kernel.org
Mon Jul 21 12:23:36 PDT 2025
On Mon, Jul 21, 2025 at 12:12:35PM -0700, Nicolin Chen wrote:
> When viommu type is IOMMU_VIOMMU_TYPE_ARM_SMMUV3, always return or init the
> standard struct arm_vsmmu, instead of going through impl_ops that must have
> its own viommu type than the standard IOMMU_VIOMMU_TYPE_ARM_SMMUV3.
>
> Given that arm_vsmmu_init() is called after arm_smmu_get_viommu_size(), any
> unsupported viommu->type must be a corruption. And it must be a driver bug
> that its vsmmu_size and vsmmu_init ops aren't paired. Warn these two cases.
>
> Suggested-by: Will Deacon <will at kernel.org>
> Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
> ---
> .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 24 ++++++++++---------
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 14 +++++++++++
> 2 files changed, 27 insertions(+), 11 deletions(-)
Cheers for the quick respin.
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 181d07bc1a9d..dfe7f40fac35 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -4703,6 +4703,7 @@ static void arm_smmu_impl_remove(void *data)
> static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu)
> {
> struct arm_smmu_device *new_smmu = ERR_PTR(-ENODEV);
> + const struct arm_smmu_impl_ops *ops;
> int ret;
>
> if (smmu->impl_dev && (smmu->options & ARM_SMMU_OPT_TEGRA241_CMDQV))
> @@ -4713,11 +4714,24 @@ static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu)
> if (IS_ERR(new_smmu))
> return new_smmu;
>
> + ops = new_smmu->impl_ops;
> + if (ops) {
> + /* vsmmu_size and vsmmu_init ops must be paired */
> + if (WARN_ON(!ops->vsmmu_size ^ !ops->vsmmu_init)) {
> + ret = -EINVAL;
> + goto err_remove;
> + }
I suppose that could be != instead of ^ to avoid mixing up logical and
arithmetic operators, but it does the trick either way so:
Acked-by: Will Deacon <will at kernel.org>
Will
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