Expose debug information if qemu errors out

[obbardc]

If an error occurs in qemu, we should expose some information to make debugging easier.

root@f7aa2ba298f2:/home# fakemachine 
KVM: entry failed, hardware error 0xffffffff
RAX=0000000000000046 RBX=0000000000000046 RCX=0000000000000040 RDX=0000000000000001
RSI=0000000000000000 RDI=0000000000060630 RBP=00000000000606b0 RSP=ffffffffb9e03d08
R8 =0000000000000010 R9 =0000000000000010 R10=0000000000000000 R11=00000000ffffffff
R12=0000000000000086 R13=ffffffffba800000 R14=0000000000000001 R15=0000000000001000
RIP=ffffffffb883ffe5 RFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0000 0000000000000000 00000000 00000000
CS =0010 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA]
SS =0000 0000000000000000 00000000 00000000
DS =0000 0000000000000000 00000000 00000000
FS =0000 0000000000000000 00000000 00000000
GS =0000 ffff91697d200000 00000000 00000000
LDT=0000 0000000000000000 00000000 00000000
TR =0040 fffffe0000003000 00004087 00008b00 DPL=0 TSS64-busy
GDT=     fffffe0000001000 0000007f
IDT=     fffffe0000000000 00000fff
CR0=80050033 CR2=ffff91693f601000 CR3=000000003dc0a001 CR4=00060630
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 
DR6=00000000ffff0ff0 DR7=0000000000000400
EFER=0000000000000d01
Code=31 e3 b9 48 83 c4 10 e9 63 1e bc 00 0f 1f 00 31 f6 0f 22 e7 <e9> 1a 00 00 00 48 8b 05 cf c7 13 01 48 89 fa 81 e2 00 08 31 00 48 39 c2 75 2d 48 85 f6 75

TODO:

• see if this error was trapped in debos/fakemachine
• expose the qemu command line we tried to run
• we could also expose this when running with debug/verbose cmdline flag