From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex@shazbot.org>
Cc: "Matt Evans" <mattev@meta.com>,
"Leon Romanovsky" <leon@kernel.org>,
"Alex Mastro" <amastro@fb.com>,
"Christian König" <christian.koenig@amd.com>,
"Mahmoud Adam" <mngyadam@amazon.de>,
"David Matlack" <dmatlack@google.com>,
"Björn Töpel" <bjorn@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Kevin Tian" <kevin.tian@intel.com>,
"Ankit Agrawal" <ankita@nvidia.com>,
"Pranjal Shrivastava" <praan@google.com>,
"Alistair Popple" <apopple@nvidia.com>,
"Vivek Kasireddy" <vivek.kasireddy@intel.com>,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
kvm@vger.kernel.org
Subject: Re: [PATCH 4/9] vfio/pci: Convert BAR mmap() to use a DMABUF
Date: Mon, 4 May 2026 04:40:41 -0300 [thread overview]
Message-ID: <afhNeYS174EW7RYp@nvidia.com> (raw)
In-Reply-To: <20260501161915.75525c15@shazbot.org>
On Fri, May 01, 2026 at 04:19:15PM -0600, Alex Williamson wrote:
> Exporting dma-bufs from vfio-pci is a feature, but mmap of MMIO BARs is
> a legacy requirement. That legacy requirement now depends on
> PCI_P2PDMA, which depends on 64BIT and ZONE_DEVICE.
That should be split up now, Leon missed it when he added the new
APIs that didn't require ZONE_DEVICE..
> ZONE_DEVICE is harder, it seems like it's possible there could be
> minimal 64-bit custom kernel configs where vfio-pci currently works
> without ZONE_DEVICE.
Several VFIO using arches cannot tolerate ZONE_DEVICE, IIRC, so we
must avoid that dependency.
I think if we clean up the kconfig for p2p so it is always available
it would be no problem to keep this patch relying on it, but that
needs to either be done in this series or before it
Jason
next prev parent reply other threads:[~2026-05-04 7:40 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-16 13:17 [PATCH 0/9] vfio/pci: Add mmap() for DMABUFs Matt Evans
2026-04-16 13:17 ` [PATCH 1/9] vfio/pci: Fix vfio_pci_dma_buf_cleanup() double-put Matt Evans
2026-04-24 18:05 ` Jason Gunthorpe
2026-05-01 19:12 ` Alex Williamson
2026-04-16 13:17 ` [PATCH 2/9] vfio/pci: Add a helper to look up PFNs for DMABUFs Matt Evans
2026-04-24 18:15 ` Jason Gunthorpe
2026-04-16 13:17 ` [PATCH 3/9] vfio/pci: Add a helper to create a DMABUF for a BAR-map VMA Matt Evans
2026-04-24 18:24 ` Jason Gunthorpe
2026-04-30 16:47 ` Matt Evans
2026-04-30 17:11 ` Jason Gunthorpe
2026-04-16 13:17 ` [PATCH 4/9] vfio/pci: Convert BAR mmap() to use a DMABUF Matt Evans
2026-05-01 22:19 ` Alex Williamson
2026-05-04 7:40 ` Jason Gunthorpe [this message]
2026-04-16 13:17 ` [PATCH 5/9] vfio/pci: Provide a user-facing name for BAR mappings Matt Evans
2026-04-24 18:26 ` Jason Gunthorpe
2026-05-01 22:44 ` Alex Williamson
2026-04-16 13:17 ` [PATCH 6/9] vfio/pci: Clean up BAR zap and revocation Matt Evans
2026-05-01 23:19 ` Alex Williamson
2026-04-16 13:17 ` [PATCH 7/9] vfio/pci: Support mmap() of a VFIO DMABUF Matt Evans
2026-04-24 18:30 ` Jason Gunthorpe
2026-04-16 13:17 ` [PATCH 8/9] vfio/pci: Permanently revoke a DMABUF on request Matt Evans
2026-04-16 13:17 ` [PATCH 9/9] vfio/pci: Add mmap() attributes to DMABUF feature Matt Evans
2026-04-24 18:31 ` Jason Gunthorpe
2026-04-26 10:52 ` Leon Romanovsky
2026-04-27 14:36 ` Alex Williamson
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