On Mon, Nov 30, 2015 at 7:01 PM, Razvan Cojocaru <rcojocaru@bitdefender.com> wrote:

On 12/01/2015 01:32 AM, Tamas K Lengyel wrote:
> Hi all,
> I'm trying to extend the current vm_event system to be able to emulate
> over an in-guest breakpoint using the VM_EVENT_FLAG_SET_EMUL_READ_DATA
> feature. The idea is to have the vm_event listener send back the
> contents of the memory that was overwritten by the breakpoint
> instruction, have Xen emulate one instruction, and resume execution
> normally afterwards. This would eliminate the need of removing the
> breakpoint, singlestepping, and placing the breakpoint back again.
>
> Unfortunately I encounter this crash when I call
> hvm_mem_access_emulate_one in the event response handler:
>
> (XEN) vm_event.c:72:d0v0 Checking flags on int3 response 37
> (XEN) Xen BUG at /share/src/xen/xen/include/asm/hvm/vmx/vmx.h:372