From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Christian König" <christian.koenig@amd.com>
Cc: Leon Romanovsky <leon@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Logan Gunthorpe <logang@deltatee.com>,
Jens Axboe <axboe@kernel.dk>, Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
Sumit Semwal <sumit.semwal@linaro.org>,
Kees Cook <kees@kernel.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Ankit Agrawal <ankita@nvidia.com>,
Yishai Hadas <yishaih@nvidia.com>,
Shameer Kolothum <skolothumtho@nvidia.com>,
Kevin Tian <kevin.tian@intel.com>,
Alex Williamson <alex@shazbot.org>,
Krishnakant Jaju <kjaju@nvidia.com>, Matt Ochs <mochs@nvidia.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-block@vger.kernel.org, iommu@lists.linux.dev,
linux-mm@kvack.org, linux-doc@vger.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, kvm@vger.kernel.org,
linux-hardening@vger.kernel.org, Alex Mastro <amastro@fb.com>,
Nicolin Chen <nicolinc@nvidia.com>
Subject: Re: [Linaro-mm-sig] [PATCH v8 06/11] dma-buf: provide phys_vec to scatter-gather mapping routine
Date: Wed, 19 Nov 2025 15:36:38 -0400 [thread overview]
Message-ID: <20251119193638.GQ17968@ziepe.ca> (raw)
In-Reply-To: <6714dc49-6b5c-4d58-9a43-95bb95873a97@amd.com>
On Wed, Nov 19, 2025 at 03:11:01PM +0100, Christian König wrote:
> I miss interpreted the call to pci_p2pdma_map_type() here in that
> now the DMA-buf code decides if transactions go over the root
> complex or not.
Oh, that's not it at all. I think you get it, but just to be really
clear:
This code is taking a physical address from the exporter and
determining how it MUST route inside the fabric. There is only one
single choice with no optionality.
The exporter already decided if it will go over the host bridge by
providing an address that must use a host bridge path.
> But the exporter can call pci_p2pdma_map_type() even before calling
> this function, so that looks fine to me.
Yes, the exporter needs to decide where the data is placed before it
tries to map it into the SGT.
Jason
next prev parent reply other threads:[~2025-11-19 19:36 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-11 9:57 [PATCH v8 00/11] vfio/pci: Allow MMIO regions to be exported through dma-buf Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 01/11] PCI/P2PDMA: Separate the mmap() support from the core logic Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 02/11] PCI/P2PDMA: Simplify bus address mapping API Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 03/11] PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 04/11] PCI/P2PDMA: Provide an access to pci_p2pdma_map_type() function Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 05/11] PCI/P2PDMA: Document DMABUF model Leon Romanovsky
2025-11-19 9:18 ` Christian König
2025-11-19 13:13 ` Leon Romanovsky
2025-11-19 13:35 ` Jason Gunthorpe
2025-11-19 14:06 ` Christian König
2025-11-19 19:45 ` Jason Gunthorpe
2025-11-19 20:45 ` Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 06/11] dma-buf: provide phys_vec to scatter-gather mapping routine Leon Romanovsky
2025-11-18 23:02 ` Jason Gunthorpe
2025-11-19 0:06 ` Nicolin Chen
2025-11-19 13:32 ` Leon Romanovsky
2025-11-19 5:54 ` Tian, Kevin
2025-11-19 13:30 ` Leon Romanovsky
2025-11-19 13:37 ` Jason Gunthorpe
2025-11-19 13:45 ` Leon Romanovsky
2025-11-19 13:16 ` [Linaro-mm-sig] " Christian König
2025-11-19 13:25 ` Jason Gunthorpe
2025-11-19 13:42 ` Christian König
2025-11-19 13:48 ` Leon Romanovsky
2025-11-19 19:31 ` Jason Gunthorpe
2025-11-19 20:54 ` Leon Romanovsky
2025-11-20 7:08 ` Christian König
2025-11-20 7:41 ` Leon Romanovsky
2025-11-20 7:54 ` Christian König
2025-11-20 8:06 ` Leon Romanovsky
2025-11-20 8:32 ` Christian König
2025-11-20 8:42 ` Leon Romanovsky
2025-11-20 13:20 ` Jason Gunthorpe
2025-11-19 13:42 ` Leon Romanovsky
2025-11-19 14:11 ` Christian König
2025-11-19 14:50 ` Leon Romanovsky
2025-11-19 14:53 ` Christian König
2025-11-19 15:41 ` Leon Romanovsky
2025-11-19 16:33 ` Leon Romanovsky
2025-11-20 7:03 ` Christian König
2025-11-20 7:38 ` Leon Romanovsky
2025-11-19 19:36 ` Jason Gunthorpe [this message]
2025-11-11 9:57 ` [PATCH v8 07/11] vfio: Export vfio device get and put registration helpers Leon Romanovsky
2025-11-18 7:10 ` Tian, Kevin
2025-11-11 9:57 ` [PATCH v8 08/11] vfio/pci: Share the core device pointer while invoking feature functions Leon Romanovsky
2025-11-18 7:11 ` Tian, Kevin
2025-11-11 9:57 ` [PATCH v8 09/11] vfio/pci: Enable peer-to-peer DMA transactions by default Leon Romanovsky
2025-11-18 7:18 ` Tian, Kevin
2025-11-18 20:10 ` Alex Williamson
2025-11-19 0:01 ` Tian, Kevin
2025-11-18 20:18 ` Keith Busch
2025-11-19 0:02 ` Tian, Kevin
2025-11-19 13:54 ` Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 10/11] vfio/pci: Add dma-buf export support for MMIO regions Leon Romanovsky
2025-11-18 7:33 ` Tian, Kevin
2025-11-18 14:28 ` Jason Gunthorpe
2025-11-18 23:56 ` Tian, Kevin
2025-11-19 19:41 ` Jason Gunthorpe
2025-11-19 20:50 ` Leon Romanovsky
2025-11-11 9:57 ` [PATCH v8 11/11] vfio/nvgrace: Support get_dmabuf_phys Leon Romanovsky
2025-11-18 7:34 ` Tian, Kevin
2025-11-18 7:59 ` Ankit Agrawal
2025-11-18 14:30 ` Jason Gunthorpe
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