> -----Original Message----- > From: Marc Zyngier [mailto:marc.zyngier@xxxxxxx] > Sent: Thursday, December 01, 2016 10:58 AM > To: Shameerali Kolothum Thodi; Paolo Bonzini; Radim Krčmář > Cc: Catalin Marinas; kvmarm@xxxxxxxxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] KVM: arm/arm64: vgic: Don't notify EOI for non- > SPIs > > On 01/12/16 10:28, Shameerali Kolothum Thodi wrote: > > Hi Marc, > > > >> -----Original Message----- > >> From: kvmarm-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:kvmarm- > >> bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Marc Zyngier > >> Sent: Thursday, December 01, 2016 9:26 AM > >> To: Paolo Bonzini; Radim Krčmář > >> Cc: Catalin Marinas; kvmarm@xxxxxxxxxxxxxxxxxxxxx; linux-arm- > >> kernel@xxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx > >> Subject: [PATCH] KVM: arm/arm64: vgic: Don't notify EOI for non-SPIs > >> > >> When we inject a level triggerered interrupt (and unless it is > backed > >> by the physical distributor - timer style), we request a maintenance > >> interrupt. Part of the processing for that interrupt is to feed to > the > >> rest of KVM (and to the eventfd subsystem) the information that the > >> interrupt has been EOIed. > >> > >> But that notification only makes sense for SPIs, and not PPIs (such > as > >> the PMU interrupt). Skip over the notification if the interrupt is > not > >> an SPI. > > > > Just to clarify my understanding, the maintenance interrupt is > generated > > for cases where there is no mapping of virt to phys interrupts > > (ie, ICH_LR HW bit is not set). And I was under the impression that > > kvm_notify_acked_irq will eventually deactivate the interrupt on > distributor > > for such cases. Its not clear to me how the deactivation is done > > otherwise. > > > > Could you please help me to understand this better. > > kvm_notify_acked_irq() doesn't do *anything* at the distributor level, > ever (it has no idea of anything GIC-specific anyway). It's sole job is > to signal the rest of the stack that an interrupt has been EOIed in the > guest. Thanks Marc. Understood. I got confused by the kvm_set_irq in the kvm_notify_acked_irq path. > For these interrupts, which are purely virtual, there is absolutely > nothing to do at the physical distributor level anyway. Furthermore, > kvm_notify_acked_irq doesn't know about per-cpu interrupt, which is why > we cannot notify them. Just to confirm, that means for any phys interrupt(PPI/SPI) to be injected to the Guest, the mapping bit has(HW bit set) to be used. Thanks, Shameer -- 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
