Description of problem:

Upstream libgcrpt git master has a change to AES-XTS that implements AES-NI acceleration. The performance improvements reported in the commit message are astonishing and I've confirmed them myself. 

commit a00c5b2988cea256c7823a76ce601febf02c790f (HEAD)
Author: Jussi Kivilinna <jussi.kivilinna>
Date:   Sat Jan 6 18:53:20 2018 +0200

    Add AES-NI acceleration for AES-XTS
    
    * cipher/cipher-internal.h (gcry_cipher_handle): Change bulk
    XTS function to take cipher context.
    * cipher/cipher-xts.c (_gcry_cipher_xts_crypt): Ditto.
    * cipher/cipher.c (_gcry_cipher_open_internal): Setup AES-NI
    XTS bulk function.
    * cipher/rijndael-aesni.c (xts_gfmul_const, _gcry_aes_aesni_xts_enc)
    (_gcry_aes_aesni_xts_enc, _gcry_aes_aesni_xts_crypt): New.
    * cipher/rijndael.c (_gcry_aes_aesni_xts_crypt)
    (_gcry_aes_xts_crypt): New.
    * src/cipher.h (_gcry_aes_xts_crypt): New.
    --
    
    Benchmarks on Intel Core i7-4790K, 4.0Ghz (no turbo):
    
    Before:
            XTS enc |      1.66 ns/B     575.7 MiB/s      6.63 c/B
            XTS dec |      1.66 ns/B     575.5 MiB/s      6.63 c/B
    
    After (~6x faster):
            XTS enc |     0.270 ns/B    3528.5 MiB/s      1.08 c/B
            XTS dec |     0.272 ns/B    3511.5 MiB/s      1.09 c/B
    
    Signed-off-by: Jussi Kivilinna <jussi.kivilinna>


Unfortunately there's been no upstream release with this code present.

This will have a massive benefit for QEMU's LUKS implementation I/O performance since AES-XTS is the default mode though. Thus from QEMU's POV we'd like to explore options for getting this performance increase available in RHEL-8. 

Whether that's a backport to 1.8.3, or waiting & rebasing to 1.9.0 in some 8.x update doesn't matter to QEMU - we'd just like to find a way to achieve this level of performance without having to wait until RHEL-9.

Version-Release number of selected component (if applicable):
libgcrypt-1.8.3-4.el8

How reproducible:
Aleays

Steps to Reproduce:
1. Run a AES-XTS performance benchmark on RHEL-8 libgcrypt 1.8.3
2. Run a AES-XTS performance benchmark on libgcrypt git master


Actual results:
Git master gcrypt is x5 or more faster than RHEL-8 gcrypt

Expected results:
RHEL-8 gcrypt is approx same speed as git upstream.

Additional info:

QEMU had been intending to make use of gnutls for ciphers, and gnutls/nettle both gained XTS support to this end. This performance boost from gcrypt git master is too large to ignore. If gnutls/nettle could be enhanced to match this performance result though in a reasonable timeframe, that could still be a viable option for QEMU too.