On 06/24/2015 12:27 AM, Lengyel, Tamas wrote: > I've extended xen-access to exercise this new feature taking into > account some of the current limitations. Using the altp2m_write|exec > options we create a duplicate view of the default hostp2m, and instead > of relaxing the mem_access permissions when we encounter a violation, we > swap the view on the violating vCPU while also enabling MTF > singlestepping. When the singlestep event fires, we use the response to > that event to swap the view back to the restricted altp2m view.
That's certainly very interesting. I wonder what the benefits are in this case over emulating the fault-causing instruction (other than obviously not going through the emulator)? The altp2m method would certainly be slower, since you need more round-trips from userspace to the hypervisor (the EPT vm_event handling + the singlestep event, whereas with emulation you just reply to the original vm_event). Regards, Razvan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
