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> >> > >> if (addr == DMA_MAPPING_ERROR) > >> return false; > >> + /* > >> + * The DMA address was derived from encrypted RAM, but this device > >> + * requires unencrypted DMA addresses. Treat it as not DMA-capable > >> + * so the caller can fall back to a suitable SWIOTLB pool. > >> + */ > >> + if (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev)) > >> + return false; > >> + > > > > I guess it does not make sense to check the other way? I'd be worried if > > some a confidential device uses shared memory which might leak info. > > > > From the perspective of the dma_capable() check, this should be allowed; > that is, a trusted device is permitted to access shared memory. Right, we have use cases that require confidential devices to use shared memory we cannot block it at the DMA layer. It would be a reasonable DMA debugging to block shared memory without the DMA ATTR CC SHARED. Jason