Avi Kivity wrote: > Dong, Eddie wrote: >> Avi Kivity wrote: >> >>> [we can try to improve it by using vm86 interrupt redirection which >>> may allow event injection using VT instead of writing to the guest >>> stack]. >>> >>> >> Avi: >> I did an investigation to try to find a way if we can deliver >> IRQ to guest real mode using VM_ENTRY_INTR_INFO like what >> is did in protect mode with minimal changes. It looks like we can't >> do that without a VMXassist similar VM86 monitor in guest. >> >> > > Can you explain why a monitor is needed? I thought of using the VME > interrupt redirection bitmap, does this approach not work?
Yes I think so at beginning. But then I realized there are tricky: VMX will restore guest state first and then inject HW IRQ if there is. (SDM 22.5) SDM 3 16.3 & 16.3.1.1 says the processor will switch to protect mode exception interrupt & exception handler instead of 8086 program IVT which we want in this case, where the VM86 monitor resides:-( Only software interrupt can let processor directly refer IVT per manual 16.3.1.1 & 22.5. So I tried to inject a software interrupt for guest external interrupt, but it violatesSDM 20.8.3 and VM Resume fails. This could be one of the major reason why Xen implemented a VMXAssist. > >> I guess this is too big change for us to solve this small >> purpose, right? And it looks like we can still survive with current >> approach :-) >> >> > > Yes, but I rather liked the reduction in code and simplification from > eliminating the special case for injecting real mode interrupts. Yes, I wanna too :-) Eddie ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
