linux-kernel - Re: [PATCH v4 0/2] iommu/amd: Support for HATdis and HATS features

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Message-ID: <tp3etuslicpk272nunywuklvkivkjyg5sx54o2n27jhngyykx3@mkj3rwgkfc2i>
Date: Thu, 26 Jun 2025 10:58:42 +0000
From: Ankit Soni <Ankit.Soni@....com>
To: <iommu@...ts.linux.dev>
CC: <vasant.hegde@....com>, <joao.m.martins@...cle.com>,
	<suravee.suthikulpanit@....com>, <joro@...tes.org>, <will@...nel.org>,
	<robin.murphy@....com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 0/2] iommu/amd: Support for HATdis and HATS features

On Wed, Jun 04, 2025 at 06:13:23AM +0000, Ankit Soni wrote:
> This series comprises two features:
> 
> HATDis: When host address translation is not supported by the IOMMU,
> the IVHD->attr[HATDis] bit is set. For instance, QEMU emulated vIOMMU
> does not support dma tranlation for VFIO passthrough device.
> Support has been added to check this bit and switch to guest page table 
> mode, if supported. This feature is useful for cases where only interrupt
> remapping is required.
> 
> EFR[HATS]: These bits indicate the maximum level supported for host page table
> by the IOMMU. Modifications have been made to adjust the maximum host page table
> level, starting with level 4. If these bits are set to 11b, the driver will
> attempt to use the guest page table.
> 
> If guest page table mode is not supported, the driver will fail to probe
> devices for DMA translations.
> The interrupt remapping will continue to be supported.
> 
> ---
> v4:
> - Relocate sysfs PD_MODE_NONE check case after iommu_device_register()
>   along with return check.
> v3:
> - Add check before populating sysfs entries for iommu groups.
> v2:
> - Addressed comments from Vasant:
> 	- Added/Modified comments and logs.
> 	- Removed v1 page table assignment hunk.
> 
> Ankit Soni (2):
>   iommu/amd: Add HATDis feature support
>   iommu/amd: Add efr[HATS] max v1 page table level
> 
>  drivers/iommu/amd/amd_iommu.h       |  2 ++
>  drivers/iommu/amd/amd_iommu_types.h |  7 ++++-
>  drivers/iommu/amd/init.c            | 47 +++++++++++++++++++++++++++--
>  drivers/iommu/amd/io_pgtable.c      |  4 +--
>  drivers/iommu/amd/iommu.c           | 15 ++++++++-
>  5 files changed, 69 insertions(+), 6 deletions(-)
> 
> -- 
> 2.43.0
> 

Gentle ping.