Failed to emulate instruction [0x40 0x22 0x3c 0x25 0x23 0xd0 0x5f 0xff 0x31 0xf6 0xb9 0xfe 0x00 0x00 0x00] at 0xffffffff800796ac

[Peter Grehan]

Hi,

> I success run RHEL 5.9/6.5/6.6 in bhyve.
> when I try boot rhel-server-5.4-x86_64-dvd.iso, the bhyve exit with
> following error
>
> Failed to emulate instruction [0x40 0x22 0x3c 0x25 0x23 0xd0 0x5f 0xff 0x31
> 0xf6 0xb9 0xfe 0x00 0x00 0x00] at 0xffffffff800796ac
>
> and with bhyve exited with status 134,
> also have a bhyve.core
>
> the FreeBSD version is SVN 11-CURRENT r291495.
>
> anything I can help to find what is going on?

  Thanks for the report. I was able to repro this and get the same error.

  Instruction emulation takes place on an EPT fault, and when bhyve 
can't handle this and exits, a 'bhyvectl --get-all' can be used to 
extraxt some post-mortem state. In this case, the gla/gpa associated 
with the exit can be found:

...
gla[0]    0xffffffffff5fd023
gpa[0]    0x00000000fee00023
...

  The gpa is in local APIC ID register. It's not 4-byte aligned, which 
is a bit unusual, so is probably a byte instruction. Putting the 
instruction bytes into a small program and using gdb as a disassembler 
gives:

(gdb) x/i &a
0x6009ec <a>:	and    0xffffffffff5fd023,%dil

  It's the 'REX + 22 /r' form of the AND instruction. This isn't 
supported by bhyve - it only des the 22/81/83 variants of AND, so will 
have to be added.

later,

Peter.