As mentioned in LP#1921880 I get an unchecked MSR access when running a focal guest with the EPYC-Rome model on a Milan CPU, but it did not crash. So if you have access to a P620, which is pretty much a Milan CPU, you should be able to reproduce this. It does not happen, if the guest has just the EPYC model. Anyway the MSR error got me on the path that this is related to the missing IBRS flag, which after trying it with the patch, the MSR error was gone. So yes, this is related to LP#1915063 and as you already concluded with this backport, it would be resolved as well.
I don't think only the kernel commit will resolve this. I have seen a similar/same MSR error without IBRS on a Fedora 33 guest which has kernel 5.11.x. So I if I have time, I test the mainline ppa kernel to confirm this. For reference, this is the MSR error on the focal guest with 5.4.0-70 on both host and guest: unchecked MSR access error: WRMSR to 0x48 (tried to write 0x0000000000000006) at rIP: 0xffffffff89a73594 (native_write_msr+0x4/0x30) Call Trace: ? __switch_to_xtra+0x1ae/0x5e0 ? __switch_to_asm+0x34/0x70 ? __switch_to_asm+0x40/0x70 ? __switch_to_asm+0x34/0x70 ? __switch_to_asm+0x40/0x70 ? __switch_to_asm+0x34/0x70 __switch_to+0x3b0/0x470 ? __switch_to_asm+0x40/0x70 ? __switch_to_asm+0x34/0x70 __schedule+0x2e3/0x740 preempt_schedule_common+0x18/0x30 _cond_resched+0x22/0x30 stop_one_cpu+0x69/0xa0 ? sched_ttwu_pending+0xe0/0xe0 sched_exec+0x92/0xc0 __do_execve_file.isra.0+0x1fc/0x840 ? strncpy_from_user+0x4c/0x150 __x64_sys_execve+0x39/0x50 do_syscall_64+0x57/0x190 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f31e09ef2fb Code: 41 89 01 eb da 66 2e 0f 1f 84 00 00 00 00 00 f7 d8 64 41 89 01 eb d6 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 3b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 65 4b 10 00 f7 d8 64 89 01 48 RSP: 002b:00007fff1cfd3b48 EFLAGS: 00000246 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 000055713f000370 RCX: 00007f31e09ef2fb RDX: 000055713f0d5010 RSI: 000055713f069690 RDI: 000055713f006070 RBP: 00007fff1cfd3d50 R08: 000055713f057cd0 R09: 0000000000000000 R10: 000055713efe9980 R11: 0000000000000246 R12: 0000000000000000 R13: 000055713f0d0f50 R14: 0000000000000000 R15: 000055713f069690 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1921754 Title: Add missing cpu feature bits in EPYC-Rome model To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1921754/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
