[PATCH v2 17/22] iommu/arm-smmu-v3-iommufd: Support implementation-defined hw_info

Nicolin Chen
2025-04-26T06:33:10Z

Repurpose the @__reserved field in the struct iommu_hw_info_arm_smmuv3,
to an HW implementation-defined field @impl.

This will be used by Tegra241 CMDQV implementation on top of a standard
ARM SMMUv3 IOMMU. The @impl will be only valid if @flags is set with an
implementation-defined flag.

Thus in the driver-level, add an hw_info impl op that will return such
a flag to use the impl field.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 1 +
include/uapi/linux/iommufd.h | 4 ++--
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 16 +++++++++++++---
3 files changed, 16 insertions(+), 5 deletions(-)

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 a5835af72417..bab7a9ce1283 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -726,6 +726,7 @@ struct arm_smmu_impl_ops {
struct arm_smmu_domain *smmu_domain, struct iommufd_ctx *ictx,
unsigned int viommu_type,
const struct iommu_user_data *user_data);
+ u32 (*hw_info)(struct arm_smmu_device *smmu, u32 *impl);
};

/* An SMMUv3 instance */
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 06a763fda47f..b2614f0f1547 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -554,7 +554,7 @@ struct iommu_hw_info_vtd {
* (IOMMU_HW_INFO_TYPE_ARM_SMMUV3)
*
* @flags: Must be set to 0
- * @__reserved: Must be 0
+ * @impl: Must be 0
* @idr: Implemented features for ARM SMMU Non-secure programming interface
* @iidr: Information about the implementation and implementer of ARM SMMU,
* and architecture version supported
@@ -585,7 +585,7 @@ struct iommu_hw_info_vtd {
*/
struct iommu_hw_info_arm_smmuv3 {
__u32 flags;
- __u32 __reserved;
+ __u32 impl;
__u32 idr[6];
__u32 iidr;
__u32 aidr;
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
index a8a78131702d..63861c60b615 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
@@ -10,7 +10,9 @@
void *arm_smmu_hw_info(struct device *dev, u32 *length, u32 *type)
{
struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+ struct arm_smmu_device *smmu = master->smmu;
struct iommu_hw_info_arm_smmuv3 *info;
+ u32 flags = 0, impl = 0;
u32 __iomem *base_idr;
unsigned int i;

@@ -18,15 +20,23 @@ void *arm_smmu_hw_info(struct device *dev, u32 *length, u32 *type)
if (!info)
return ERR_PTR(-ENOMEM);

- base_idr = master->smmu->base + ARM_SMMU_IDR0;
+ base_idr = smmu->base + ARM_SMMU_IDR0;
for (i = 0; i <= 5; i++)
info->idr[i] = readl_relaxed(base_idr + i);
- info->iidr = readl_relaxed(master->smmu->base + ARM_SMMU_IIDR);
- info->aidr = readl_relaxed(master->smmu->base + ARM_SMMU_AIDR);
+ info->iidr = readl_relaxed(smmu->base + ARM_SMMU_IIDR);
+ info->aidr = readl_relaxed(smmu->base + ARM_SMMU_AIDR);

*length = sizeof(*info);
*type = IOMMU_HW_INFO_TYPE_ARM_SMMUV3;

+ if (smmu->impl_ops && smmu->impl_ops->hw_info) {
+ flags = smmu->impl_ops->hw_info(smmu, &impl);
+ if (flags) {
+ info->impl = impl;
+ info->flags |= flags;
+ }
+ }
+
return info;
}

--
2.43.0