kernel panic caused by virtualbox(?)

[Don Lewis]

Reposted to -current to get some more eyes on this ...

I just got a kernel panic when I started up a CentOS 7 VM in virtualbox.
The host is:
	FreeBSD 12.0-CURRENT #17 r302500 GENERIC amd64
The virtualbox version is:
	virtualbox-ose-5.0.26
	virtualbox-ose-kmod-5.0.26_1

The panic message is:

panic: Unregistered use of FPU in kernel
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe085a55d030
vpanic() at vpanic+0x182/frame 0xfffffe085a55d0b0
kassert_panic() at kassert_panic+0x126/frame 0xfffffe085a55d120
trap() at trap+0x7ae/frame 0xfffffe085a55d330
calltrap() at calltrap+0x8/frame 0xfffffe085a55d330
--- trap 0x16, rip = 0xffffffff827dd3a9, rsp = 0xfffffe085a55d408, rbp = 0xfffffe085a55d430 ---
g_pLogger() at 0xffffffff827dd3a9/frame 0xfffffe085a55d430
g_pLogger() at 0xffffffff8274e5c7/frame 0x3
KDB: enter: panic

Since g_pLogger is a symbol in vboxdrv.ko, it looks like virtualbox is
the trigger.

There are no symbols for the virtualbox kmods, possibly because I
installed them as an upgrade using packages (built with the same source
tree version) instead of by using PORTS_MODULES in make.conf, so ports
kgdb didn't have anything useful to say about what happened before the
trap.

This panic is very repeatable.  I just got another one when starting the
same VM., but this time the two calls before the trap were
null_bug_bypass().  Hmn, that symbol is in nullfs ...

I don't see this with a Windows 7 VM.

All of the virtualbox kmod files are compiled with -mno-mmx -mno-sse
-msoft-float -mno-aes -mno-avx