kvm: emulation failure

[Ram Pai <linuxram@us.ibm.com>]

I see this problem with a x86 sles10 guest running on x86_64 intel host.
If the guest is reset abruptly and rebooted, some where 
before grub sequence it hangs and the following message is seen in the
logs

emulation failed (pagetable) rip 7ed5 66 60 ac 20.

I located this instruction sequence in isolinux.bin on the iso ;if that
is relevant.


I did some analysis and find that there is an ept violation, which is
handled and then the next instruction '66 60' is attempted to decode 
and emulate. But decode fails. kvm continues loops in the kernel
in __vcpu_run().

the code path is 

kvm_run() -> __vcpu_run() -> vcpu_enter_guest() -> kvm_handle_exit() ->
handle_ept_violation() -> kvm_mmu_page_fault() -> emulate_instruction() ->
x86_decode_insn()


Any insights here on how to fix the problem is appreciated. And if a fix already exists even better :)

thanks,
RP