Messages in this thread | | | Date | Thu, 6 Jan 2022 17:25:34 +0100 | Subject | Re: [dm-devel] [PATCH v4 00/13] x86: Support Key Locker | From | Milan Broz <> |
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On 06/01/2022 06:07, Eric Biggers wrote: > On Wed, Jan 05, 2022 at 09:55:17PM +0000, Bae, Chang Seok wrote: >>>> +-----------+---------------+---------------+ >>>> | Cipher | Encryption | Decryption | >>>> | (AES-KL) | (MiB/s) | (MiB/s) | >>>> +-----------+---------------+---------------+ >>>> | AES-CBC | 505.3 | 2097.8 | >>>> | AES-XTS | 1130 | 696.4 | >>>> +-----------+-------------------------------+ >>> >>> Why is AES-XTS decryption so much slower than AES-XTS encryption? They should >>> be about the same. >> >> Analyzing and understanding this with specific hardware implementation takes >> time for us. Will come back and update you when we have anything to share here. > > Note that for disk encryption, decryption performance is usually more important > than encryption performance. So your performance results are strange.
If the test results are from "cryptsetup benchmark", it just run benchmark through userspace crypto API (AF_ALG) - no dm-crypt is involved at all.
Proper test with dm-crypt should be run to get some numbers too.
(But the test results are really strange... there is no reason decryption should be slower for XTS.)
Also you mention that > Bare metal disk encryption is the only use case intended by these patches. > Userspace usage is not supported because there is no ABI provided to > communicate and coordinate wrapping-key restore failures to userspace.
The cryptsetup benchmark is userspace use (just with kernel netlink access to kernel crypto). So I am not sure if these number are so important.
Milan
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