From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF2DA1D5146; Thu, 11 Sep 2025 11:33:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757590426; cv=none; b=kk0PSyC3CBWehFgaNcTwY9jYVldnOwNuz8sijdaedWRmrkro0VgicXdAjvnMLkZomBTxiH82Rce4GR81Av8O4Frmh9vjGu0Is/6CQzD6m8XaDIQi2ziihKa79lXESFkHFUeGtp6R790iJuciS43Z8WRyA52UeGWFwQg3ZISfURg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757590426; c=relaxed/simple; bh=rQckTyKjw0KD4frgMJweuSbbmKII/CXI2ZszG9S0ebs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=U6r+sd997FKa1DqdMj3Sc5DRndOJdMWwbIAjRqFhmmOh7EA2aFz8ODHjjcXGrPYcwSwpUTbhIgGSUyJFos1T3BPaqLOpLkFcfpl9JxwGZtUG5JYk+gxEK2f5hlxpd0XUW/vLREPA18gLm72arJUJM9YWehVubJo4qE6mfr9PEGc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FuT4EEy7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FuT4EEy7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AA16C4CEF0; Thu, 11 Sep 2025 11:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757590425; bh=rQckTyKjw0KD4frgMJweuSbbmKII/CXI2ZszG9S0ebs=; h=From:To:Cc:Subject:Date:From; b=FuT4EEy7c2rpuhn+Sige2uAlDkOrkz0Lap5ivExfloCc8AME0HL8VSQ8H3UwFNeaR 9fB4KpiIyvlKO0Mc6EqzzcjStHt9HwZxefXK5c4OSHBV1BfBOdi/Qgn/D4foBcqAkX GX0QmwP27iI6x4/DoqmrxuGWKvL4HzTkQnzcMldl1K3KWC3r0rxckuzcOcGbH0C68P Gff1WrmpKE8q6LHavcC0Hj59QeofoCmTmSKbW1fDGc0hVf+IKcTrrJ4EUlc7PRbVSu K+5OL4HtbfwI0vGfKMqPgZMnbUhDWmIfQqwnHWly4QSaPNELWGd1mGrWq7s1xnjalJ cQTAN3mxPpl8g== From: Leon Romanovsky To: Alex Williamson Cc: Jason Gunthorpe , Andrew Morton , Bjorn Helgaas , =?UTF-8?q?Christian=20K=C3=B6nig?= , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, Jens Axboe , Joerg Roedel , kvm@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Logan Gunthorpe , Marek Szyprowski , Robin Murphy , Sumit Semwal , Vivek Kasireddy , Will Deacon Subject: [PATCH v2 00/10] vfio/pci: Allow MMIO regions to be exported through dma-buf Date: Thu, 11 Sep 2025 14:33:04 +0300 Message-ID: X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Changelog: v2: * Added extra patch which adds new CONFIG, so next patches can reuse it. * Squashed "PCI/P2PDMA: Remove redundant bus_offset from map state" into the other patch. * Fixed revoke calls to be aligned with true->false semantics. * Extended p2pdma_providers to be per-BAR and not global to whole device. * Fixed possible race between dmabuf states and revoke. * Moved revoke to PCI BAR zap block. v1: https://lore.kernel.org/all/cover.1754311439.git.leon@kernel.org * Changed commit messages. * Reused DMA_ATTR_MMIO attribute. * Returned support for multiple DMA ranges per-dMABUF. v0: https://lore.kernel.org/all/cover.1753274085.git.leonro@nvidia.com --------------------------------------------------------------------------- Based on "[PATCH v6 00/16] dma-mapping: migrate to physical address-based API" https://lore.kernel.org/all/cover.1757423202.git.leonro@nvidia.com/ series. --------------------------------------------------------------------------- This series extends the VFIO PCI subsystem to support exporting MMIO regions from PCI device BARs as dma-buf objects, enabling safe sharing of non-struct page memory with controlled lifetime management. This allows RDMA and other subsystems to import dma-buf FDs and build them into memory regions for PCI P2P operations. The series supports a use case for SPDK where a NVMe device will be owned by SPDK through VFIO but interacting with a RDMA device. The RDMA device may directly access the NVMe CMB or directly manipulate the NVMe device's doorbell using PCI P2P. However, as a general mechanism, it can support many other scenarios with VFIO. This dmabuf approach can be usable by iommufd as well for generic and safe P2P mappings. In addition to the SPDK use-case mentioned above, the capability added in this patch series can also be useful when a buffer (located in device memory such as VRAM) needs to be shared between any two dGPU devices or instances (assuming one of them is bound to VFIO PCI) as long as they are P2P DMA compatible. The implementation provides a revocable attachment mechanism using dma-buf move operations. MMIO regions are normally pinned as BARs don't change physical addresses, but access is revoked when the VFIO device is closed or a PCI reset is issued. This ensures kernel self-defense against potentially hostile userspace. The series includes significant refactoring of the PCI P2PDMA subsystem to separate core P2P functionality from memory allocation features, making it more modular and suitable for VFIO use cases that don't need struct page support. ----------------------------------------------------------------------- The series is based originally on https://lore.kernel.org/all/20250307052248.405803-1-vivek.kasireddy@intel.com/ but heavily rewritten to be based on DMA physical API. ----------------------------------------------------------------------- The WIP branch can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?h=dmabuf-vfio-v2 Thanks Leon Romanovsky (8): PCI/P2PDMA: Separate the mmap() support from the core logic PCI/P2PDMA: Simplify bus address mapping API PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation PCI/P2PDMA: Export pci_p2pdma_map_type() function types: move phys_vec definition to common header vfio/pci: Add dma-buf export config for MMIO regions vfio/pci: Enable peer-to-peer DMA transactions by default vfio/pci: Add dma-buf export support for MMIO regions :wqa Vivek Kasireddy (2): vfio: Export vfio device get and put registration helpers vfio/pci: Share the core device pointer while invoking feature functions block/blk-mq-dma.c | 7 +- drivers/iommu/dma-iommu.c | 4 +- drivers/pci/p2pdma.c | 165 ++++++++---- drivers/vfio/pci/Kconfig | 20 ++ drivers/vfio/pci/Makefile | 2 + drivers/vfio/pci/vfio_pci_config.c | 22 +- drivers/vfio/pci/vfio_pci_core.c | 59 +++-- drivers/vfio/pci/vfio_pci_dmabuf.c | 398 +++++++++++++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 23 ++ drivers/vfio/vfio_main.c | 2 + include/linux/pci-p2pdma.h | 114 +++++---- include/linux/types.h | 5 + include/linux/vfio.h | 2 + include/linux/vfio_pci_core.h | 4 + include/uapi/linux/vfio.h | 25 ++ kernel/dma/direct.c | 4 +- mm/hmm.c | 2 +- 17 files changed, 734 insertions(+), 124 deletions(-) create mode 100644 drivers/vfio/pci/vfio_pci_dmabuf.c -- 2.51.0