[PATCH v1 02/16] iommu/dma: handle MMIO path in dma_iova_link
From: Leon Romanovsky <leon@kernel.org>
Date: 2025-08-04 12:43:18
Also in:
linux-block, linux-doc, linux-iommu, linux-mm, linux-nvme, linuxppc-dev, lkml, rust-for-linux, virtualization, xen-devel
Subsystem:
iommu dma-api layer, iommu subsystem, the rest · Maintainers:
Robin Murphy, Joerg Roedel, Will Deacon, Linus Torvalds
From: Leon Romanovsky <leonro@nvidia.com> Make sure that CPU is not synced if MMIO path is taken. Signed-off-by: Leon Romanovsky <leonro@nvidia.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