The problem has to do with virtualization and it seems that with the new bios the kvm_amd module on any kernel I've tried occurs some kernel errors.
I've tried different kernels and I get the same issues. The error message when trying to load the kvm_amd module is:
[ 484.232185] INFO: task systemd-udevd:495 blocked for more than 120 seconds.
[ 484.232191] Tainted: P OE 4.18.4-041804-generic #201808220230
[ 484.232192] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 484.232195] systemd-udevd D 0 495 471 0x80000124
[ 484.232198] Call Trace:
[ 484.232206] __schedule+0x29e/0x840
[ 484.232209] schedule+0x2c/0x80
[ 484.232218] __sev_do_cmd_locked+0x219/0x280 [ccp]
[ 484.232222] ? wait_woken+0x80/0x80
[ 484.232228] sev_do_cmd+0x2f/0x50 [ccp]
[ 484.232231] ? 0xffffffffc14c8000
[ 484.232235] sev_get_api_version+0x36/0xa0 [ccp]
[ 484.232240] ? sp_get_psp_master_device+0x68/0x80 [ccp]
[ 484.232244] psp_pci_init+0x45/0x230 [ccp]
[ 484.232247] ? kobject_uevent+0xb/0x10
[ 484.232250] ? driver_register+0x9e/0xc0
[ 484.232251] ? 0xffffffffc14c8000
[ 484.232255] sp_mod_init+0x1a/0x1000 [ccp]
[ 484.232258] do_one_initcall+0x4a/0x1c4
[ 484.232260] ? _cond_resched+0x19/0x30
[ 484.232263] ? kmem_cache_alloc_trace+0xb8/0x1d0
[ 484.232265] ? do_init_module+0x27/0x220
[ 484.232267] do_init_module+0x60/0x220
[ 484.232268] load_module+0x149b/0x1830
[ 484.232272] __do_sys_finit_module+0xbd/0x120
[ 484.232273] ? __do_sys_finit_module+0xbd/0x120
[ 484.232275] __x64_sys_finit_module+0x1a/0x20
[ 484.232277] do_syscall_64+0x5a/0x110
[ 484.232279] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 484.232281] RIP: 0033:0x7f587a0a6839
[ 484.232281] Code: Bad RIP value.
[ 484.232287] RSP: 002b:00007ffee470b138 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[ 484.232289] RAX: ffffffffffffffda RBX: 0000564472da5b60 RCX: 00007f587a0a6839
[ 484.232290] RDX: 0000000000000000 RSI: 00007f5879d850e5 RDI: 0000000000000007
[ 484.232291] RBP: 00007f5879d850e5 R08: 0000000000000000 R09: 00007ffee470b250
[ 484.232292] R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000
[ 484.232293] R13: 0000564472d8ec40 R14: 0000000000020000 R15: 0000564472da5b60
Of course, amd-v and iommu are enabled in the BIOS.
I've noe reverted back to 1.15A and KVM works again fine.