linux-kernel - Re: [PATCH v5 00/14] iommu/amd: Introduce Nested Translation support

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Message-ID: <aRZTAgxpA8/7216A@Asurada-Nvidia>
Date: Thu, 13 Nov 2025 13:52:02 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
CC: <jgg@...dia.com>, <linux-kernel@...r.kernel.org>, <robin.murphy@....com>,
	<will@...nel.org>, <joro@...tes.org>, <kevin.tian@...el.com>,
	<jsnitsel@...hat.com>, <vasant.hegde@....com>, <iommu@...ts.linux.dev>,
	<santosh.shukla@....com>, <sairaj.arunkodilkar@....com>, <jon.grimm@....com>,
	<prashanthpra@...gle.com>, <wvw@...gle.com>, <wnliu@...gle.com>,
	<gptran@...gle.com>, <kpsingh@...gle.com>, <joao.m.martins@...cle.com>,
	<alejandro.j.jimenez@...cle.com>
Subject: Re: [PATCH v5 00/14] iommu/amd: Introduce Nested Translation support

On Wed, Nov 12, 2025 at 06:24:52PM +0000, Suravee Suthikulpanit wrote:
> Note: This series is rebased on top of:
>  * Git repo: git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git 
>    Branch: next
>    Commit: 91920a9d87f5 ("Merge branches 'arm/smmu/updates', 'arm/smmu/bindings',
>                           'mediatek', 'nvidia/tegra', 'amd/amd-vi' and 'core' 
>                           into next")
>  * [PATCH v5] iommu/amd: Add support for hw_info for iommu capability query
>    https://lore.kernel.org/linux-iommu/20250926141901.511313-1-suravee.suthikulpanit@amd.com/T/#u 

Nit: this patch doesn't apply cleanly on 91920a9d87f5 :-/

>  drivers/iommu/amd/Makefile          |   2 +-
>  drivers/iommu/amd/amd_iommu.h       |  36 ++++
>  drivers/iommu/amd/amd_iommu_types.h |  48 +++++-
>  drivers/iommu/amd/init.c            |   8 +
>  drivers/iommu/amd/iommu.c           | 221 +++++++++++++++---------
>  drivers/iommu/amd/iommufd.c         |  50 ++++++
>  drivers/iommu/amd/iommufd.h         |   5 +
>  drivers/iommu/amd/nested.c          | 259 ++++++++++++++++++++++++++++
>  include/uapi/linux/iommufd.h        |  11 ++

So, this seems to be a preparatory series for AMD vIOMMU, yet it
doesn't properly work since it's missing IOMMUFD_VIOMMU_TYPE_AMD
and the invalidation component (HW_QUEUE).

However, the series does declare IOMMU_HWPT_DATA_AMD_GUEST in the
uAPI header. I am afraid that might confuse user who might think
AMD now supports virtualization using the HWPT-based mode, like
Intel VT-d.

So, maybe we should either:
  - leave a note at IOMMU_HWPT_DATA_AMD_GUEST to declare it is
    incomplete yet, and remove later
  - keep IOMMU_HWPT_DATA_AMD_GUEST in an AMD driver header, and
    move to the uAPI header later

Jason?

Nicolin