2016-01-22 12:00+0800, Yang Zhang: > On 2016/1/22 1:21, rkrcmar@xxxxxxxxxx wrote: >>(I think there isn't a practical difference between *r=-1 and *r=0.) > > Currently, if *r == -1, the remote_irr may get set. But it seems wrong. I Yeah ... > need to have a double check to see whether it is a bug in current code. Looking forward to the patch! Thanks. >>'ret = true' is the better one. We know that the interrupt is not >>deliverable [1], so there's no point in trying to deliver with the slow >>path. We behave similarly when the interrupt targets a single disabled >>APIC. >> >>--- >>1: Well ... it's possible that slowpath would deliver it thanks to >> different handling of disabled APICs, but it's undefined behavior, > > why it is undefined behavior? Besides, why we will keep two different > handling logic for the fast path and slow path? It looks weird. It does look very weird ... the slow path would require refactoring, though, so we save effort without a considerable drawback. (I would love if it behaved identically, but I don't want to force it on someone and likely won't do it myself ...) I consider it undefined because SMD says that an OS musn't configure this behavior and doesn't say what should happen if the OS does => we could do anything. (Killing the guest would be great for debugging OS issues, but ours behavior is fairly conservative.) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
