[PATCH v6 06/16] iommu/dma: implement DMA_ATTR_MMIO for iommu_dma_(un)map_phys()
From: Leon Romanovsky <leon@kernel.org>
Date: 2025-09-09 13:28:35
Also in:
linux-block, linux-doc, linux-iommu, linux-mm, linux-nvme, linux-trace-kernel, 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 iommu_dma_map_phys() and iommu_dma_unmap_phys() respect DMA_ATTR_MMIO. DMA_ATTR_MMIO makes the functions behave the same as iommu_dma_(un)map_resource(): - No swiotlb is possible - No cache flushing is done (ATTR_MMIO should not be cached memory) - prot for iommu_map() has IOMMU_MMIO not IOMMU_CACHE This is preparation for replacing iommu_dma_map_resource() callers with iommu_dma_map_phys(DMA_ATTR_MMIO) and removing iommu_dma_(un)map_resource(). Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> --- drivers/iommu/dma-iommu.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index aea119f32f965..6804aaf034a16 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c@@ -1211,16 +1211,19 @@ dma_addr_t iommu_dma_map_phys(struct device *dev, phys_addr_t phys, size_t size, */ if (dev_use_swiotlb(dev, size, dir) && iova_unaligned(iovad, phys, size)) { + if (attrs & DMA_ATTR_MMIO) + return DMA_MAPPING_ERROR; + phys = iommu_dma_map_swiotlb(dev, phys, size, dir, attrs); if (phys == (phys_addr_t)DMA_MAPPING_ERROR) return DMA_MAPPING_ERROR; } - if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) + if (!coherent && !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO))) arch_sync_dma_for_device(phys, size, dir); iova = __iommu_dma_map(dev, phys, size, prot, dma_mask); - if (iova == DMA_MAPPING_ERROR) + if (iova == DMA_MAPPING_ERROR && !(attrs & DMA_ATTR_MMIO)) swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs); return iova; }
@@ -1228,10 +1231,14 @@ dma_addr_t iommu_dma_map_phys(struct device *dev, phys_addr_t phys, size_t size, void iommu_dma_unmap_phys(struct device *dev, dma_addr_t dma_handle, size_t size, enum dma_data_direction dir, unsigned long attrs) { - struct iommu_domain *domain = iommu_get_dma_domain(dev); phys_addr_t phys; - phys = iommu_iova_to_phys(domain, dma_handle); + if (attrs & DMA_ATTR_MMIO) { + __iommu_dma_unmap(dev, dma_handle, size); + return; + } + + phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dma_handle); if (WARN_ON(!phys)) return;
--
2.51.0