From a7ba70f1787f977f970cd116076c6fce4b9e01cc Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Thu, 21 Nov 2019 10:26:44 +0100 Subject: dma-mapping: treat dev->bus_dma_mask as a DMA limit Using a mask to represent bus DMA constraints has a set of limitations. The biggest one being it can only hold a power of two (minus one). The DMA mapping code is already aware of this and treats dev->bus_dma_mask as a limit. This quirk is already used by some architectures although still rare. With the introduction of the Raspberry Pi 4 we've found a new contender for the use of bus DMA limits, as its PCIe bus can only address the lower 3GB of memory (of a total of 4GB). This is impossible to represent with a mask. To make things worse the device-tree code rounds non power of two bus DMA limits to the next power of two, which is unacceptable in this case. In the light of this, rename dev->bus_dma_mask to dev->bus_dma_limit all over the tree and treat it as such. Note that dev->bus_dma_limit should contain the higher accessible DMA address. Signed-off-by: Nicolas Saenz Julienne Reviewed-by: Robin Murphy Signed-off-by: Christoph Hellwig --- arch/x86/mm/mem_encrypt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index 9268c12458c8..a03614bd3e1a 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -367,7 +367,7 @@ bool force_dma_unencrypted(struct device *dev) if (sme_active()) { u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask)); u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask, - dev->bus_dma_mask); + dev->bus_dma_limit); if (dma_dev_mask <= dma_enc_mask) return true; -- cgit v1.2.3