Re: [PATCH v6 04/20] dma-pool: track decrypted atomic pools and select them via attrs
From: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Date: 2026-06-11 05:26:11
Also in:
linux-arm-kernel, linux-coco, linux-iommu, linux-s390, lkml
Jason Gunthorpe [off-list ref] writes:
The sashiko note does look legit though:
if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
!gfpflags_allow_blocking(gfp) && !coherent) {
page = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &cpu_addr,
gfp, attrs, NULL);
if (!page)
return NULL;
I don't see anything doing the force_dma_unencrypted test along this
callchain..
I guess it should be done one step up in dma_alloc_attrs() instead of
in dma_direct_alloc()?I think we should do something similar to what dma_map_phys() does here, considering that we only support DMA direct with DMA_ATTR_CC_SHARED/DMA_ATTR_ALLOC_CC_SHARED.
@@ -637,6 +637,7 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, { const struct dma_map_ops *ops = get_dma_ops(dev); void *cpu_addr; + bool is_cc_shared; WARN_ON_ONCE(!dev->coherent_dma_mask);
@@ -657,8 +658,17 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, /* let the implementation decide on the zone to allocate from: */ flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); + if (force_dma_unencrypted(dev)) + attrs |= DMA_ATTR_ALLOC_CC_SHARED; + + is_cc_shared = attrs & DMA_ATTR_CC_SHARED; + if (dma_alloc_direct(dev, ops) || arch_dma_alloc_direct(dev)) { cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, attrs); + } else if (is_cc_shared) { + trace_dma_alloc(dev, NULL, 0, size, DMA_BIDIRECTIONAL, flag, + attrs); + return NULL; } else if (use_dma_iommu(dev)) { cpu_addr = iommu_dma_alloc(dev, size, dma_handle, flag, attrs); } else if (ops->alloc) { -aneesh