linux-kernel - [PATCH v1 02/16] iommu/dma: handle MMIO path in dma_iova

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Message-ID: <52e39cd31d8f30e54a27afac84ea35f45ae4e422.1754292567.git.leon@kernel.org>
Date: Mon,  4 Aug 2025 15:42:36 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Leon Romanovsky <leonro@...dia.com>,
	Jason Gunthorpe <jgg@...dia.com>,
	Abdiel Janulgue <abdiel.janulgue@...il.com>,
	Alexander Potapenko <glider@...gle.com>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@....de>,
	Danilo Krummrich <dakr@...nel.org>,
	iommu@...ts.linux.dev,
	Jason Wang <jasowang@...hat.com>,
	Jens Axboe <axboe@...nel.dk>,
	Joerg Roedel <joro@...tes.org>,
	Jonathan Corbet <corbet@....net>,
	Juergen Gross <jgross@...e.com>,
	kasan-dev@...glegroups.com,
	Keith Busch <kbusch@...nel.org>,
	linux-block@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-nvme@...ts.infradead.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-trace-kernel@...r.kernel.org,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	rust-for-linux@...r.kernel.org,
	Sagi Grimberg <sagi@...mberg.me>,
	Stefano Stabellini <sstabellini@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	virtualization@...ts.linux.dev,
	Will Deacon <will@...nel.org>,
	xen-devel@...ts.xenproject.org
Subject: [PATCH v1 02/16] iommu/dma: handle MMIO path in dma_iova_link

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

Make sure that CPU is not synced if MMIO path is taken.

Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
 drivers/iommu/dma-iommu.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index ea2ef53bd4fef..399838c17b705 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1837,13 +1837,20 @@ static int __dma_iova_link(struct device *dev, dma_addr_t addr,
 		phys_addr_t phys, size_t size, enum dma_data_direction dir,
 		unsigned long attrs)
 {
-	bool coherent = dev_is_dma_coherent(dev);
+	int prot;
 
-	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
-		arch_sync_dma_for_device(phys, size, dir);
+	if (attrs & DMA_ATTR_MMIO)
+		prot = dma_info_to_prot(dir, false, attrs) | IOMMU_MMIO;
+	else {
+		bool coherent = dev_is_dma_coherent(dev);
+
+		if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+			arch_sync_dma_for_device(phys, size, dir);
+		prot = dma_info_to_prot(dir, coherent, attrs);
+	}
 
 	return iommu_map_nosync(iommu_get_dma_domain(dev), addr, phys, size,
-			dma_info_to_prot(dir, coherent, attrs), GFP_ATOMIC);
+			prot, GFP_ATOMIC);
 }
 
 static int iommu_dma_iova_bounce_and_link(struct device *dev, dma_addr_t addr,
@@ -1949,9 +1956,13 @@ int dma_iova_link(struct device *dev, struct dma_iova_state *state,
 		return -EIO;
 
 	if (dev_use_swiotlb(dev, size, dir) &&
-	    iova_unaligned(iovad, phys, size))
+	    iova_unaligned(iovad, phys, size)) {
+		if (attrs & DMA_ATTR_MMIO)
+			return -EPERM;
+
 		return iommu_dma_iova_link_swiotlb(dev, state, phys, offset,
 				size, dir, attrs);
+	}
 
 	return __dma_iova_link(dev, state->addr + offset - iova_start_pad,
 			phys - iova_start_pad,
-- 
2.50.1