> One more thing... Does the protection_keys kernel selftest hit any > errors on this same setup? It does a lot of PKRU sanity checking and > I'm a bit surprised it hasn't caught something yet. Hi Dave, This issue does reproduce with the self tests too, my simple test program also fails consistently [1], all it does is spin executing RDPKRU waiting for a context switch to clobber the value. $ ./test unexpected value on iteration 3772082 value:0x55555554 expected:0x55555550 ========================== self tests: $ ./protection_keys_64 has pkeys: 1 startup pkey_reg: 0000000055555550 WARNING: not run as root, can not do hugetlb test test 0 PASSED (iteration 1) test 1 PASSED (iteration 1) test 2 PASSED (iteration 1) test 3 PASSED (iteration 1) test 4 PASSED (iteration 1) test 5 PASSED (iteration 1) protection_keys_64: pkey-helpers.h:127: _read_pkey_reg: Assertion `pkey_reg == shadow_pkey_reg' failed. Aborted (core dumped) $ uname -a Linux localhost 5.13.0-17189-g62fb9874f5da #12 SMP PREEMPT Tue Nov 9 01:29:44 UTC 2021 x86_64 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz GenuineIntel GNU/Linux Let me know if I can provide anything else, I'm happy to help troubleshoot this. Thanks, Brian 1. https://gist.github.com/bgaff/e4b5457ab1cf5126fea6327666c63441
