I've tested the different hw implementations (amd64, arm64, s390x) and they are all ok.

Fix looks good to me. This could be tested with new long running test (tests/hashtest) that would allocate 4GiB+ pattern block for inputting to gcry_md_write.

@werner Could these two patches could be backported to 2.2? These changes give same level of performance increase in 2.2 as seen in 2.3.

Patch applied to master with small changes.

Thanks for updated patch. I'm travelling next week and have time to check it closely only after I'm back. On quick glance, it looks good. What is also needed is the changelog for git commit log.

I meant interleaving integer register based 1xPoly1305 with 8xChacha20 as is done for 4xChacha20 in cipher/chacha20-ppc.c (interleaved so that for each 4xChaCha20 processed, 4 blocks of 1xPoly1305 is executed). Quite often microarchitectures have separate execution units for integer registers and vector registers and then it makes sense to interleave integer-poly1305 with vector-chacha20 as algorithms do not end up competing for same execution resources. Interleaving vector-poly1305 and vector-chacha20 is not likely to give performance increase (and likely to run problems with running out of vector registers).

Problem is that new assembly is using VSX registers vs14-vs31 which overlap with floating-point registers f14-f31. f14-f31 are ABI callee saved, so those need to be stored and restored.

Tested patch with small change so that HWF_PPC_ARCH_3_00 is used instead of HWF_PPC_ARCH_3_10. Building bench-slope with "-O3 -flto" makes bug in new implementation visible. Without new implementations bench-slope is ok (testing with QEMU):

$ tests/bench-slope --disable-hwf ppc-arch_3_00 cipher chacha20
Cipher:
 CHACHA20       |  nanosecs/byte   mebibytes/sec   cycles/byte
     STREAM enc |      2.35 ns/B     405.0 MiB/s         - c/B
     STREAM dec |      2.32 ns/B     410.7 MiB/s         - c/B
   POLY1305 enc |      2.46 ns/B     388.0 MiB/s         - c/B
   POLY1305 dec |      2.34 ns/B     408.1 MiB/s         - c/B
  POLY1305 auth |     0.238 ns/B      4003 MiB/s         - c/B

-O2 problem with bench-slope seems strange. Does problem appear after this patch is applied?

Fixed in master. I rechecked that bulk implementation passes tests with qemu-ppc64le.

Looks like that line went missing in third/final version of AES-GCM patch at https://dev.gnupg.org/T5700

Fix pushed to master. Updated graph: