On Tue, Oct 9, 2018 at 10:04 AM, Liran Alon <liran.alon@xxxxxxxxxx> wrote: > Today, KVM_GET_VCPU_EVENTS IOCTL returns in events->exception.injected > the value of (vcpu->arch.exception.pending || vcpu->arch.exception.injected). > Which means userspace have no way of knowing if exception was re-injected > and thus cannot be intercepted by L1 or it is still pending and therefore can be intercepted. > > Similarly, KVM_SET_VCPU_EVENTS IOCTL sets cpu->arch.exception.pending > to the value of events->exception.injected. Which means userspace only have the > ability to inject exceptions which cannot be intercepted by a L1 guest. > > Before this series, userspace must have assumed that exception cannot be intercepted > as exception side-effects (payload) is assumed to already been done by userspace. > Now however, it is possible for userspace to set a pending exception via IOCTL together > with it’s pending exception such that it can be correctly intercepted by L1. Yes, that seems like a mess that should be cleaned up and tied to the new capability.
