2016-09-29 17:41-0400, Paolo Bonzini: >> Another possible optimization: when delivering an IPI, don't write the >> vector to PIR, but directly to VIRR. If the guest is not in VMX >> non-root mode, then vm entry will take care of the injection; in the >> other case, we'll send POSTED_INTR_VECTOR. >> It seems that we don't even have to set PI.ON -- SDM doesn't say it is >> necessary to evaluate pending virtual interrupts after receiving the >> notification interrupt. If we have to set PI.ON, we can just skip the >> PIR->VIRR sync as long as the VM doesn't have an assigned device, >> because we know that PIR is empty. > > Nope, you cannot write to the APIC page while the VM is running.
True, thanks. > (We're already reading the manual in such a way as to "allow" us to > write TMR while the VM is running, but that should not be extended. > For example the SDM doesn't say that the processor accesses VIRR with > atomic instructions, in fact it probably doesn't). Yeah, TMR is not used by the hardware ...
