linux-kernel - [PATCH v2 3/4] iommufd: Require DMABUF revoke semantics

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Message-ID: <20260118-dmabuf-revoke-v2-3-a03bb27c0875@nvidia.com>
Date: Sun, 18 Jan 2026 14:08:47 +0200
From: Leon Romanovsky <leon@...nel.org>
To: Sumit Semwal <sumit.semwal@...aro.org>,
	Christian König <christian.koenig@....com>,
	Alex Deucher <alexander.deucher@....com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Gerd Hoffmann <kraxel@...hat.com>,
	Dmitry Osipenko <dmitry.osipenko@...labora.com>,
	Gurchetan Singh <gurchetansingh@...omium.org>,
	Chia-I Wu <olvaffe@...il.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Leon Romanovsky <leon@...nel.org>,
	Kevin Tian <kevin.tian@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Alex Williamson <alex@...zbot.org>
Cc: linux-media@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linaro-mm-sig@...ts.linaro.org,
	linux-kernel@...r.kernel.org,
	amd-gfx@...ts.freedesktop.org,
	virtualization@...ts.linux.dev,
	intel-xe@...ts.freedesktop.org,
	linux-rdma@...r.kernel.org,
	iommu@...ts.linux.dev,
	kvm@...r.kernel.org
Subject: [PATCH v2 3/4] iommufd: Require DMABUF revoke semantics

From: Leon Romanovsky <leonro@...dia.com>

IOMMUFD does not support page fault handling, and after a call to
.invalidate_mappings() all mappings become invalid. Ensure that
the IOMMUFD DMABUF importer is bound to a revoke‑aware DMABUF exporter
(for example, VFIO).

Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
 drivers/iommu/iommufd/pages.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c
index 76f900fa1687..a5eb2bc4ef48 100644
--- a/drivers/iommu/iommufd/pages.c
+++ b/drivers/iommu/iommufd/pages.c
@@ -1501,16 +1501,22 @@ static int iopt_map_dmabuf(struct iommufd_ctx *ictx, struct iopt_pages *pages,
 		mutex_unlock(&pages->mutex);
 	}
 
-	rc = sym_vfio_pci_dma_buf_iommufd_map(attach, &pages->dmabuf.phys);
+	rc = dma_buf_pin(attach);
 	if (rc)
 		goto err_detach;
 
+	rc = sym_vfio_pci_dma_buf_iommufd_map(attach, &pages->dmabuf.phys);
+	if (rc)
+		goto err_unpin;
+
 	dma_resv_unlock(dmabuf->resv);
 
 	/* On success iopt_release_pages() will detach and put the dmabuf. */
 	pages->dmabuf.attach = attach;
 	return 0;
 
+err_unpin:
+	dma_buf_unpin(attach);
 err_detach:
 	dma_resv_unlock(dmabuf->resv);
 	dma_buf_detach(dmabuf, attach);
@@ -1656,6 +1662,7 @@ void iopt_release_pages(struct kref *kref)
 	if (iopt_is_dmabuf(pages) && pages->dmabuf.attach) {
 		struct dma_buf *dmabuf = pages->dmabuf.attach->dmabuf;
 
+		dma_buf_unpin(pages->dmabuf.attach);
 		dma_buf_detach(dmabuf, pages->dmabuf.attach);
 		dma_buf_put(dmabuf);
 		WARN_ON(!list_empty(&pages->dmabuf.tracker));

-- 
2.52.0