> -----Original Message----- > From: Paolo Bonzini [mailto:pbonz...@redhat.com] > Sent: Wednesday, September 28, 2016 7:50 PM > To: Wu, Feng <feng...@intel.com>; Michael S. Tsirkin <m...@redhat.com> > Cc: linux-kernel@vger.kernel.org; k...@vger.kernel.org; > yang.zhang...@gmail.com; rkrc...@redhat.com > Subject: Re: [PATCH 2/3] kvm: x86: do not use KVM_REQ_EVENT for APICv > interrupt injection > > > > On 28/09/2016 13:40, Wu, Feng wrote: > > IIUIC, the issue you describe above is that IPI for posted-interrupts may be > > issued between > > > > vcpu->mode = IN_GUEST_MODE; > > > > and > > > > local_irq_disable(); > > > > But if that really happens, we will call kvm_vcpu_kick() in > > vmx_deliver_posted_interrupt(), hence the vcpu->mode will be changed > > to EXITING_GUEST_MODE, then we will goto cancel_injection in > > vcpu_enter_guest, so the posted-interrupt will be delivered to guest > > in the next vmentry. Seems I cannot see the problem. Do I miss something? > > No, if that happens kvm_trigger_posted_interrupt returns true, hence > kvm_vcpu_kick is not called.
Oops, I missed the "!" before the function call ... > With the fix, the IPI is processed as soon > as the guest enters non-root mode, and the interrupt is injected. Exactly! > > > The other issue occurs when the IPI is sent between > > kvm_x86_ops->hwapic_irr_update(vcpu, > kvm_lapic_find_highest_irr(vcpu)); > > and > > vcpu->mode = IN_GUEST_MODE; > > In this case, kvm_vcpu_kick is called but it (correctly) doesn't do > anything because it sees vcpu->mode == OUTSIDE_GUEST_MODE. Then the > guest is entered with PIR.ON, but the PI interrupt is not pending and > hence the interrupt is never delivered to the guest. Why "never", at least, the interrupt should be delivered to the guest in the next vm-entry, right? I mean vm-entry -> vm-exit -> _vm-entry_ (interrupts will be delivered at this vm-entery). Thanks, Feng > The fix for this > is to move the RVI update after IN_GUEST_MODE. Then the source CPU uses > the posted interrupt IPI instead of kvm_cpu_kick, and everything works. > > Paolo
