> -----Original Message----- > From: Radim Krčmář [mailto:rkrc...@redhat.com] > Sent: Friday, January 22, 2016 12:20 AM > To: Wu, Feng <feng...@intel.com> > Cc: pbonz...@redhat.com; linux-kernel@vger.kernel.org; > k...@vger.kernel.org > Subject: Re: [PATCH v3 1/4] KVM: Recover IRTE to remapped mode if the > interrupt is not single-destination > > 2016-01-20 09:42+0800, Feng Wu: > > When the interrupt is not single destination any more, we need > > to change back IRTE to remapped mode explicitly. > > > > Signed-off-by: Feng Wu <feng...@intel.com> > > --- > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > > @@ -10764,8 +10764,17 @@ static int vmx_update_pi_irte(struct kvm > *kvm, unsigned int host_irq, > > - if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) > > + if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) { > > + /* > > + * Make sure the IRTE is in remapped mode if > > + * we don't handle it in posted mode. > > + */ > > + pi_set_sn(vcpu_to_pi_desc(vcpu)); > > What could go wrong if we didn't suppress notifications here?
This is a good question. I also thought about this before, but after thinking it a bit more, seems we don't need to do this. If we don't do this, the in-flight interrupts will continue to be delivered in PI mode while we are changing it to remapped mode in IRTE. Even if we do this, the in-flight interrupts are also delivered in PI mode before setting 'SN' anyway, so seems we really don't need this, what is your opinion? Thanks, Feng Thanks, Feng > > Thanks. > > > + ret = irq_set_vcpu_affinity(host_irq, NULL); > > + pi_clear_sn(vcpu_to_pi_desc(vcpu)); > > + > > continue; > > + }
