On Tue, Apr 12, 2022 at 10:32:58AM +0100, Catalin Marinas wrote: > > At a quick grep, most cra_alignmask values are currently 15 or smaller. > I'm not convinced the driver needs to know about the CPU cache > alignment. We could set cra_alignmask to CRYPTO_MINALIGN but that would > incur unnecessary overhead via function like setkey_unaligned() when the > arch_kmalloc_minalign() was already sufficient for DMA safety. > > Maybe I miss some use-cases or I focus too much on DMA safety. The alignment was never designed for DMA. It's mainly for CPUs that provide accelerated instructions that require a certain amount of alignment, most commonly 16 bytes. Therefore CRYPTO_MINALIGN was never meant to be a guarantee for DMA alignment. Any drivers relying on this is simply broken. I understand that on ARM for historical reasons you have had a situation that CRYPTO_MINALIGN happened to be large enough to guarantee DMA alignment. I totally agree with your patch to try to fix this but it should not penalise other architectures and raise the CRYPTO_MINALIGN unnecessarily. I think if CRYPTO_MINALIGN makes those drivers work then so should cra_alignmask. And that would be a relatively easy patch to do. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
