RE: [PATCH v4 22/23] iommu/tegra241-cmdqv: Add user-space use support

Tian, Kevin
2025-05-15T08:28:03Z

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Friday, May 9, 2025 11:03 AM
>
> /**
> * struct iommu_hw_info_arm_smmuv3 - ARM SMMUv3 hardware
> information
> * (IOMMU_HW_INFO_TYPE_ARM_SMMUV3)
> *
> - * @flags: Must be set to 0
> - * @impl: Must be 0
> + * @flags: Combination of enum iommu_hw_info_arm_smmuv3_flags
> + * @impl: Implementation-defined bits when the following flags are set:
> + * - IOMMU_HW_INFO_ARM_SMMUV3_HAS_TEGRA241_CMDQV
> + * Bits[15:12] - Log2 of the total number of SID replacements
> + * Bits[11:08] - Log2 of the total number of VINTFs per vIOMMU
> + * Bits[07:04] - Log2 of the total number of VCMDQs per vIOMMU
> + * Bits[03:00] - Version number for the CMDQ-V HW

hmm throughout this series I drew an equation between VINTF
and vIOMMU. Not sure how multiple VINTFs can be represented
w/o introducing more objects. Do we want to keep such info here?

> + * - suggest to back the queue memory with contiguous physical
> pages or
> + * a single huge page with alignment of the queue size, limit
> vSMMU's
> + * IDR1.CMDQS to the huge page size divided by 16 bytes
> + */
> + IOMMU_HW_QUEUE_TYPE_TEGRA241_CMDQV = 1,

Not sure about the last sentence. 'limit' refers to a certain action
which the user should perform?

> +
> + ret = tegra241_vintf_init_lvcmdq(vintf, lidx, vcmdq);
> + if (ret)
> + goto undepend_vcmdq;
> +
> + dev_dbg(cmdqv->dev, "%sallocated\n",
> + lvcmdq_error_header(vcmdq, header, 64));
> +
> + tegra241_vcmdq_map_lvcmdq(vcmdq);
> +
> + vcmdq->cmdq.q.q_base = q_base & VCMDQ_ADDR;
> + vcmdq->cmdq.q.q_base |= log2size;
> +
> + ret = tegra241_vcmdq_hw_init_user(vcmdq);
> + if (ret)
> + goto unmap_lvcmdq;
> + vintf->lvcmdqs[lidx] = vcmdq;

this is already done in tegra241_vintf_init_lvcmdq().