linux-kernel - Re: [PATCH] vfio: selftests: Drop IOMMU mapping size assertions for VFIO_TYPE1

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Message-ID: <20260119133748.2eaf7996@shazbot.org>
Date: Mon, 19 Jan 2026 13:37:48 -0700
From: Alex Williamson <alex@...zbot.org>
To: David Matlack <dmatlack@...gle.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, Shuah Khan
 <shuah@...nel.org>
Subject: Re: [PATCH] vfio: selftests: Drop IOMMU mapping size assertions for
 VFIO_TYPE1_IOMMU

On Wed, 14 Jan 2026 21:12:52 +0000
David Matlack <dmatlack@...gle.com> wrote:

> Drop the assertions about IOMMU mappings sizes for VFIO_TYPE1_IOMMU
> modes (both the VFIO mode and the iommufd compatibility mode). These
> assertions fail when CONFIG_IOMMUFD_VFIO_CONTAINER is enabled, since
> iommufd compatibility mode provides different huge page behavior than
> VFIO for VFIO_TYPE1_IOMMU. VFIO_TYPE1_IOMMU is an old enough interface
> that it's not worth changing the behavior of VFIO and iommufd to match
> nor care about the IOMMU mapping sizes.
> 
> Cc: Jason Gunthorpe <jgg@...pe.ca>
> Link: https://lore.kernel.org/kvm/20260109143830.176dc279@shazbot.org/
> Signed-off-by: David Matlack <dmatlack@...gle.com>
> ---
>  tools/testing/selftests/vfio/vfio_dma_mapping_test.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)

Applied to vfio next branch for v6.20/7.0.  Thanks,

Alex

> diff --git a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
> index 5397822c3dd4..ecadd0e6b61b 100644
> --- a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
> +++ b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
> @@ -162,12 +162,8 @@ TEST_F(vfio_dma_mapping_test, dma_map_unmap)
>  	if (rc == -EOPNOTSUPP)
>  		goto unmap;
>  
> -	/*
> -	 * IOMMUFD compatibility-mode does not support huge mappings when
> -	 * using VFIO_TYPE1_IOMMU.
> -	 */
> -	if (!strcmp(variant->iommu_mode, "iommufd_compat_type1"))
> -		mapping_size = SZ_4K;
> +	if (self->iommu->mode->iommu_type == VFIO_TYPE1_IOMMU)
> +		goto unmap;
>  
>  	ASSERT_EQ(0, rc);
>  	printf("Found IOMMU mappings for IOVA 0x%lx:\n", region.iova);
> 
> base-commit: d721f52e31553a848e0e9947ca15a49c5674aef3