Jul 18, 2018 14:48:23 GMT -8 tcrider84 said:
Managed to get it resolved! Sure enough kernel needed to be recompiled with CONFIG_CRYPTO_DEV_SP_PSP=n and I also changed these:CONFIG_KVM_AMD=m to CONFIG_KVM_AMD=y just in case. Probably overkill but it's for sure working again.

Jul 17 23:36:16 zenith kernel: [ 131.619989] sysrq: SysRq : Show Blocked State
Jul 17 23:36:16 zenith kernel: [ 131.620016] task PC stack pid father
Jul 17 23:36:16 zenith kernel: [ 131.620086] systemd-udevd D12624 7505 6593 0x80000120
Jul 17 23:36:16 zenith kernel: [ 131.620121] Call Trace:
Jul 17 23:36:16 zenith kernel: [ 131.620143] ? __schedule+0x35b/0x730
Jul 17 23:36:16 zenith kernel: [ 131.620169] schedule+0x37/0x90
Jul 17 23:36:16 zenith kernel: [ 131.620195] __sev_do_cmd_locked+0xb3/0x130 [ccp]
Jul 17 23:36:16 zenith kernel: [ 131.620233] ? wait_woken+0x80/0x80
Jul 17 23:36:16 zenith kernel: [ 131.620260] __sev_platform_init_locked+0x26/0x40 [ccp]
Jul 17 23:36:16 zenith kernel: [ 131.620296] sev_platform_init+0x18/0x30 [ccp]
Jul 17 23:36:16 zenith kernel: [ 131.620328] psp_pci_init+0x2b/0xb0 [ccp]
Jul 17 23:36:16 zenith kernel: [ 131.620356] ? driver_register+0x7b/0xc0
Jul 17 23:36:16 zenith kernel: [ 131.620387] sp_mod_init+0x11/0x1000 [ccp]
Jul 17 23:36:16 zenith kernel: [ 131.620413] ? 0xffffffffc09b6000
Jul 17 23:36:16 zenith kernel: [ 131.620435] do_one_initcall+0x35/0x1c0
Jul 17 23:36:16 zenith kernel: [ 131.620461] ? free_unref_page_commit.isra.90+0x5f/0xc0
Jul 17 23:36:16 zenith kernel: [ 131.620494] ? kmem_cache_alloc_trace+0x167/0x1d0
Jul 17 23:36:16 zenith kernel: [ 131.620526] do_init_module+0x56/0x1ef
Jul 17 23:36:16 zenith kernel: [ 131.620551] load_module+0x20be/0x2970
Jul 17 23:36:16 zenith kernel: [ 131.620578] ? kernel_read_file+0x16d/0x190
Jul 17 23:36:16 zenith kernel: [ 131.620607] ? __do_sys_finit_module+0xa2/0xb0
Jul 17 23:36:16 zenith kernel: [ 131.620634] __do_sys_finit_module+0xa2/0xb0
Jul 17 23:36:16 zenith kernel: [ 131.620663] do_syscall_64+0x43/0xf0
Disabling PSP prevents those SEV calls being made to PSP, which lead to lockup.
So I guess the real BUG is in the PSP firmware which now does something unexpected when SEV is being queried. I'd imagine that with previous AGESA versions PSP returned something like "error, not implemented" (TR does not support SEV) but now returns something unexpected or never returns anything.