From: "Christian König" <christian.koenig@amd.com>
To: Leon Romanovsky <leon@kernel.org>
Cc: David Hu <dhu@x6u.co>,
sumit.semwal@linaro.org, alex@shazbot.org, ankita@nvidia.com,
chriscli@google.com, david.laight.linux@gmail.com,
dri-devel@lists.freedesktop.org, iommu@lists.linux.dev,
jgg@ziepe.ca, jmoroni@google.com, kevin.tian@intel.com,
kpberry@google.com, linaro-mm-sig@lists.linaro.org,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
nicolinc@nvidia.com, praan@google.com, sashiko-bot@kernel.org,
stable@vger.kernel.org, viursachi@google.com,
xuehaohu@google.com
Subject: Re: [PATCH v8 0/2] dma-buf: Fix silent overflow and alignment
Date: Wed, 2 Sep 2026 15:34:18 +0200 [thread overview]
Message-ID: <7471c6e1-fbba-4430-a196-3f57a73505b7@amd.com> (raw)
In-Reply-To: <20260902105919.GV24140@unreal>
On 9/2/26 12:59, Leon Romanovsky wrote:
...
>> The PCI_P2PDMA_MAP_BUS_ADDR is not supported by DMA-buf and as far as I can see is a complete dead end.
>
> Maybe you mean DRM, but VFIO works perfectly with PCI_P2PDMA_MAP_BUS_ADDR flow in DMA-buf.
> What am I missing?
Well not quite.
The approach PCI_P2PDMA_MAP_BUS_ADDR takes is fundamentally tied to only map a physical CPU address into a PCI address and doesn't take into account that in a lot of configurations the CPU can't access all resources.
So when VFIO uses PCI_P2PDMA_MAP_BUS_ADDR it only works for a small subset of the use cases DMA-buf supports, but yeah as always in DMA-buf pretty much everything is optional.
Regards,
Christian.
>
> Thanks
next prev parent reply other threads:[~2026-09-02 13:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 17:08 [PATCH v8 0/2] dma-buf: Fix silent overflow and alignment David Hu
2026-09-01 17:08 ` [PATCH v8 1/2] dma-buf: Fix silent overflow for phys vec to sgt David Hu
2026-09-01 17:08 ` [PATCH v8 2/2] dma-buf: Split sgl by largest page-aligned chunk David Hu
2026-09-02 12:08 ` Jason Gunthorpe
2026-09-02 23:07 ` David Hu
2026-09-03 13:49 ` Jason Gunthorpe
2026-09-03 16:36 ` Leon Romanovsky
2026-09-02 7:00 ` [PATCH v8 0/2] dma-buf: Fix silent overflow and alignment Christian König
2026-09-02 7:39 ` Leon Romanovsky
2026-09-02 7:56 ` Christian König
2026-09-02 8:32 ` Leon Romanovsky
2026-09-02 8:44 ` Christian König
2026-09-02 9:53 ` Leon Romanovsky
2026-09-02 10:00 ` Christian König
2026-09-02 10:59 ` Leon Romanovsky
2026-09-02 13:34 ` Christian König [this message]
2026-09-02 17:46 ` Jason Gunthorpe
2026-09-02 13:42 ` Pranjal Shrivastava
2026-09-02 12:03 ` Jason Gunthorpe
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