port-riscv/58006: ATF tests no longer complete on riscv-riscv64

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         58006
>Category:       port-riscv
>Synopsis:       ATF tests no longer complete on riscv-riscv64
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-riscv-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Mar 07 12:50:00 +0000 2024
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2023.09.03.08.48.20
>Organization:
>Environment:
System: NetBSD
Architecture: riscv
Machine: riscv64
>Description:

When running the ATF test suite on the riscv-riscv64 port under qemu,
the OS crashes or hangs, usually during the raidframe tests as in this
log:

  https://www.gson.org/netbsd/bugs/build/riscv-riscv64/2024/2024.02.01.02.41.56/test.log

The problem started with the commit to "Fix and enable MULTIPROCESSOR":

  2023.09.03.08.48.19 skrll src/sys/arch/riscv/conf/GENERIC.common 1.7
  2023.09.03.08.48.19 skrll src/sys/arch/riscv/conf/files.riscv 1.14
  2023.09.03.08.48.19 skrll src/sys/arch/riscv/fdt/cpu_fdt.c 1.3
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/include/cpu.h 1.14
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/include/intr.h 1.5
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/include/pmap.h 1.21
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/cpu.c 1.5
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/cpu_subr.c 1.4
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/db_interface.c 1.4
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/ipifuncs.c 1.2
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/locore.S 1.43
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/pmap_machdep.c 1.19
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/riscv_machdep.c 1.34
  2023.09.03.08.48.20 skrll src/sys/arch/riscv/riscv/riscv_tlb.c 1.2

Logs from around the time of that commit are at:

  https://www.gson.org/netbsd/bugs/build/riscv-riscv64/commits-2023.09.html#2023.09.02.21.54.55

>How-To-Repeat:

Install misc/py-anita >= 2.11 and emulators/qemu, and run

  anita test http://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/latest/riscv-riscv64/

>Fix: