Hello! > It's a bit weird to just sned this as a new patch without replying to my > mail from yesterday with feedback
Sorry. But changes are actually minimal, and i remember that i replied to you with the promise of testing your suggestion. So, done, works fine. :) > I think you're missing a potential change to the irq_pending_on_cpu > field here, which you have to compute by calling vgic_update_state() > like we do elsewhere when we change status bits I have just checked this. vgic_update_state() never resets this bit. This bit is reset only in __kvm_vgic_flush_hwstate() and only if we have consumed completely everything. I have followed through the code and looks like it's perfectly safe to have this bit set while nothing is actually pendng. Following __kvm_vgic_flush_hwstate(), having this bit cleared is actually a shorthand for "no interrupt is pending at all". If it is set without any interrupt actually being pending (this ends up in pa_percpu and pa_shared being all zeroes), all three for_each_set_bit() loops will just not do anything, and we still get to "epilog:" label, just after a bit longer check. And, since we are here, the guest has already been disturbed. > different from the incorrect approach I suggested yesterday where we > always just clear the bit for that vcpu). Yes, it is extremely bad idea to clear it because this bit summarizes all interrupts for this vcpu, and clearing it means that we are going to lose everything. An alternate would be: clear the bit, THEN call vgic_update_state() which would set it back if necessary. But does this extra bit of complexity worth anything, given one paragraph above? Kind regards, Pavel Fedin Expert Engineer Samsung Electronics Research center Russia -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
