Dear all, It seems that currently, on UD interception KVM does not exit completely. Virtualized execution finishes, KVM executes ud_intercept() after which it enters virtualized execution again.
I am working on accelerating with virtualized execution a simulator that emulates system calls. Essentially doing virtualized execution without a OS kernel. In order to make this work, I had to modify my the KVM kernel module such that ud_intercept() return 0 and not 1 which break KVM __vcpu_run loop. This is necessary as I need to trap syscall instructions, exit virtualized execution with UD exception, emulate the system call in the simulator and after the system call is done enter back in virtualized mode and start execution with the help of KVM. So by modifying ud_intercept() to return 0, I got all this to work. Is it possible to achieve the same effect (exit on undefined opcode) without modifying ud_intercept()? It seems that re-entering virtualized execution on UD interception gives the user the flexibility of running binaries with newer instructions on older hardware, if kvm is able to emulate the newer instructions. I do not fully understand the details of this scenario, is there such a scenario or is it likely that ud_interception() will change? Thank you in advance! Best regards, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
