Re: [PATCH v1 06/16] iommu/dma: extend iommu_dma_*map_phys API to handle MMIO memory
From: Jason Gunthorpe <jgg@nvidia.com>
Date: 2025-08-07 12:07:19
Also in:
linux-block, linux-doc, linux-iommu, linux-mm, linux-nvme, linuxppc-dev, lkml, rust-for-linux, virtualization, xen-devel
On Mon, Aug 04, 2025 at 03:42:40PM +0300, Leon Romanovsky wrote:
From: Leon Romanovsky <leonro@nvidia.com> Combine iommu_dma_*map_phys with iommu_dma_*map_resource interfaces in order to allow single phys_addr_t flow.
Some later patch deletes iommu_dma_map_resource() ? Mention that plan here?
quoted hunk ↗ jump to hunk
--- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c@@ -1193,12 +1193,17 @@ static inline size_t iova_unaligned(struct iova_domain *iovad, phys_addr_t phys, dma_addr_t iommu_dma_map_phys(struct device *dev, phys_addr_t phys, size_t size, enum dma_data_direction dir, unsigned long attrs) { - bool coherent = dev_is_dma_coherent(dev); - int prot = dma_info_to_prot(dir, coherent, attrs); struct iommu_domain *domain = iommu_get_dma_domain(dev); struct iommu_dma_cookie *cookie = domain->iova_cookie; struct iova_domain *iovad = &cookie->iovad; dma_addr_t iova, dma_mask = dma_get_mask(dev); + bool coherent; + int prot; + + if (attrs & DMA_ATTR_MMIO) + return __iommu_dma_map(dev, phys, size, + dma_info_to_prot(dir, false, attrs) | IOMMU_MMIO, + dma_get_mask(dev));
I realize that iommu_dma_map_resource() doesn't today, but shouldn't
this be checking for swiotlb:
if (dev_use_swiotlb(dev, size, dir) &&
iova_unaligned(iovad, phys, size)) {
Except we have to fail for ATTR_MMIO?
Now that we have ATTR_MMIO, should dma_info_to_prot() just handle it
directly instead of open coding the | IOMMU_MMIO and messing with the
coherent attribute?
Jason