Re: [PATCH v6 04/20] dma-pool: track decrypted atomic pools and select them via attrs

On Thu, 11 Jun 2026 08:37:40 -0300
Jason Gunthorpe [off-list ref] wrote:

On Thu, Jun 11, 2026 at 10:55:47AM +0530, Aneesh Kumar K.V wrote:

quoted

Jason Gunthorpe [off-list ref] writes:
  

quoted

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.  

Yeah, I think that's the right idea for now..

quoted

+	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);  

But it would be clearer to put the test in the iommu_ functions I
think, since they are the ones that have the issue. We will need to
fix it someday..

I think we can ignore the op-> functions, arches cannot support CC and
still use dma_map_ops..

Hm, sounds reasonable. Should we probably enforce this at configure or
build time?

Petr T