From: Jason Gunthorpe <jgg@nvidia.com>
To: Mikko Perttunen <mperttunen@nvidia.com>
Cc: "Alistair Popple" <apopple@nvidia.com>,
linux-rdma@vger.kernel.org, dri-devel@lists.freedesktop.org,
christian.koenig@amd.com, sumit.semwal@linaro.org,
"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
"Simona Vetter" <simona.vetter@ffwll.ch>,
"Matthew Brost" <matthew.brost@intel.com>,
"Vivek Kasireddy" <vivek.kasireddy@intel.com>,
"Dongwon Kim" <dongwon.kim@intel.com>,
"Leon Romanovsky" <leonro@nvidia.com>,
"Kevin Tian" <kevin.tian@intel.com>,
"Xu Yilun" <yilun.xu@linux.intel.com>,
"Baolu Lu" <baolu.lu@linux.intel.com>,
"Felix Kuehling" <felix.kuehling@amd.com>,
"Alex Deucher" <alexander.deucher@amd.com>,
intel-xe@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
iommu@lists.linux.dev, "Alexey Kardashevskiy" <aik@amd.com>,
zhipingz@meta.com, treding@nvidia.com, jhubbard@nvidia.com,
"Karl Mehltretter" <kmehltretter@gmail.com>
Subject: Re: [PATCH 23/26] treewide: Rename dma_buf_attach() to dma_buf_sgt_attach()
Date: Tue, 27 Oct 2026 09:33:08 -0300 [thread overview]
Message-ID: <20261027123308.GC1671235@nvidia.com> (raw)
In-Reply-To: <jB0baKUEStaR7DFEykw_Qw@nvidia.com>
On Tue, Oct 27, 2026 at 12:42:32PM +0900, Mikko Perttunen wrote:
> > This page-side use predates the series, so the fault is not itself a v2
> > regression. Is dma_buf_sgt_attach() valid for this call site, or does Tegra
> > need a page/physical mapping type first?
>
> Sounds like a bug in TegraDRM; we should be using the DMA addr/length
> for the explicit IOMMU mapping as the sgt attachment is for the dummy
> DRM device explicitly intended to give us physical addresses.
No, you cannot connect dmabuf to an iommu_domain. It is 100% always
illegal. DMABUF does not support this. Do not pass sg_dma to iommu
functions either.
> I'm currently in the process of removing the whole explicit IOMMU path
> so if this only occurs with CONFIG_DMABUF_DEBUG enabled, I don't think
> there's a pressing need to fix this before then.
Yes I think this is probably the only way to fix it :| You have to
always use the DMA API
Jason
next prev parent reply other threads:[~2026-10-27 12:33 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-26 5:35 [PATCH 00/26] DMA-buf mapping types Alistair Popple
2026-10-26 5:35 ` [PATCH 01/26] dma-buf: Introduce " Alistair Popple
2026-10-26 7:00 ` sashiko-bot
2026-10-26 5:35 ` [PATCH 02/26] dma-buf: Add the SGT DMA mapping type Alistair Popple
2026-10-26 7:04 ` sashiko-bot
2026-10-26 5:35 ` [PATCH 03/26] dma-buf: Add dma_buf_mapping_attach() Alistair Popple
2026-10-26 7:20 ` sashiko-bot
2026-10-26 5:35 ` [PATCH 04/26] dma-buf: Route SGT related actions through attach->map_type Alistair Popple
2026-10-26 7:29 ` sashiko-bot
2026-10-26 5:35 ` [PATCH 05/26] dma-buf: Let the exporter select mapping type at pin/map Alistair Popple
2026-10-26 7:39 ` sashiko-bot
2026-10-26 8:03 ` Karl Mehltretter
2026-10-27 5:46 ` Alistair Popple
2026-10-26 5:35 ` [PATCH 06/26] dma-buf: Add match set queries for exporter placement decisions Alistair Popple
2026-10-26 7:42 ` sashiko-bot
2026-10-26 5:35 ` [PATCH 07/26] dma-buf: Add dma_buf_mapping_map() returning a type-tagged mapping Alistair Popple
2026-10-26 7:56 ` sashiko-bot
2026-10-26 5:35 ` [PATCH 08/26] dma-buf: Allow single exporter drivers to avoid the match_mapping function Alistair Popple
2026-10-26 7:58 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 09/26] drm: Check the SGT ops for drm_gem_map_dma_buf() Alistair Popple
2026-10-26 8:02 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 10/26] dma-buf: Convert all the simple exporters to use SGT mapping type Alistair Popple
2026-10-26 8:12 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 11/26] drm/vmwgfx: Use match_mapping instead of dummy calls Alistair Popple
2026-10-26 8:13 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 12/26] accel/habanalabs: Use the SGT_P2P mapping type Alistair Popple
2026-10-26 8:18 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 13/26] drm/xe/dma-buf: Use the SGT " Alistair Popple
2026-10-26 8:34 ` sashiko-bot
2026-10-27 4:26 ` Alistair Popple
2026-10-26 5:36 ` [PATCH 14/26] drm/amdgpu: " Alistair Popple
2026-10-26 8:46 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 15/26] vfio/pci: Change the DMA-buf exporter to use mapping_type Alistair Popple
2026-10-26 9:00 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 16/26] RDMA/uverbs: Use the SGT_P2P mapping type Alistair Popple
2026-10-26 9:16 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 17/26] dma-buf: Update dma_buf_phys_vec_to_sgt() to use the SGT " Alistair Popple
2026-10-26 9:26 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 18/26] iio: buffer: convert " Alistair Popple
2026-10-26 9:28 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 19/26] functionfs: " Alistair Popple
2026-10-26 9:35 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 20/26] dma-buf: Remove unused SGT stuff from the common structures Alistair Popple
2026-10-26 9:39 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 21/26] treewide: Rename dma_buf_map_attachment(_unlocked) to dma_buf_sgt_ Alistair Popple
2026-10-26 9:49 ` sashiko-bot
2026-10-27 12:05 ` Christian König
2026-10-27 12:35 ` Jason Gunthorpe
2026-10-26 5:36 ` [PATCH 22/26] treewide: Rename dma_buf_unmap_attachment(_unlocked) to dma_buf_sgt_* Alistair Popple
2026-10-26 9:56 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 23/26] treewide: Rename dma_buf_attach() to dma_buf_sgt_attach() Alistair Popple
2026-10-26 10:01 ` sashiko-bot
2026-10-27 2:15 ` Karl Mehltretter
2026-10-27 3:42 ` Mikko Perttunen
2026-10-27 12:33 ` Jason Gunthorpe [this message]
2026-10-27 13:34 ` Mikko Perttunen
2026-10-27 13:43 ` Christian König
2026-10-27 12:11 ` Christian König
2026-10-27 12:31 ` Jason Gunthorpe
2026-10-27 12:07 ` Christian König
2026-10-27 12:38 ` Jason Gunthorpe
2026-10-27 13:17 ` Christian König
2026-10-27 14:08 ` Jason Gunthorpe
2026-10-27 14:28 ` Christian König
2026-10-27 14:44 ` Jason Gunthorpe
2026-10-27 14:54 ` Christian König
2026-10-26 5:36 ` [PATCH 24/26] treewide: Rename dma_buf_dynamic_attach() to dma_buf_sgt_dynamic_attach() Alistair Popple
2026-10-26 10:13 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 25/26] dma-buf: Add kunit tests for mapping type Alistair Popple
2026-10-26 10:19 ` sashiko-bot
2026-10-26 5:36 ` [PATCH 26/26] dma-buf: Add kunit tests for mapping type selection Alistair Popple
2026-10-26 10:22 ` sashiko-bot
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