kern/55643: AMD Epyc 7351P hangs after printing 'AMD Cryptographic Coprocessor'

[alnsn%yandex.ru@localhost]

>Number:         55643
>Category:       kern
>Synopsis:       AMD Epyc 7351P hangs after printing 'AMD Cryptographic Coprocessor'
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Sep 05 12:50:00 +0000 2020
>Originator:     Alexander Nasonov
>Release:        9.99.72
>Organization:
>Environment:
Recent amd64/conf/GENERIC with spectre mitigations disabled.
>Description:
My server stopped booting somewhere between 9.99.65 and 9.99.69. I suspect it's related to recent cgd refactoring but I don't have time to bisect.


Last lines on the console before it hangs:

AMD Family17h PCIe Dummy Function (non-essential instrumentation, subclass 0x00) at pci6 dev 0 function 0 not configured
amdccp0 at pci6 dev 0 function 2: AMD Cryptographic Coprocessor
xhci0 at pci6 dev 0 function 3: AMD Family17h xHCI (rev 0x00)
xhci0: interrupting at msix2 vec 0
usb0 at xhci0: USB revision 3.0
usb1 at xhci0: USB revision 2.0
pchb5 at pci0 dev 8 function 0: AMD Family17h PCIe (rev 0x00)
ppb6 at pci0 dev 8 function 1: AMD Family17h PCIe (rev 0x00)
ppb6: PCI Express capability version 2 <Root port on PCI-E Root Complex> x16 @ 8.0GT/s
pci7 at ppb6 bus 11
AMD Product 1455 (non-essential instrumentation, subclass 0x00) at pci7 dev 0 function 0 not configured
amdccp1 at pci7 dev 0 function 1: AMD Cryptographic Coprocessor
>How-To-Repeat:
 
>Fix: