> -----Original Message----- > From: Paolo Bonzini [mailto:pbonzini@xxxxxxxxxx] > Sent: Thursday, September 17, 2015 5:42 PM > To: Wu, Feng; alex.williamson@xxxxxxxxxx; joro@xxxxxxxxxx; > mtosatti@xxxxxxxxxx > Cc: eric.auger@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v8 03/13] KVM: Define a new interface > kvm_intr_is_single_vcpu() > > > > On 17/09/2015 05:17, Wu, Feng wrote: > >>> > > + if (irq->dest_mode == APIC_DEST_PHYSICAL) { > >>> > > + if (irq->dest_id == 0xFF) > >>> > > + goto out; > >>> > > + > >>> > > + if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) { > >> > > >> > Warning here is wrong, the guest can trigger it. > > Could you please share more information about how the guest > > triggers these conditions (including the following two), Thanks > > a lot! > > irq->dest_id is a 16-bit value, so it can be > 255. Yes, irq->dest_id is defined as u32, but by looking the current KVM code, seems desst_id is used as an u8 variable, even in x2apic mode the dest_id will not beyond 255 (except for broadcast dest in in x2apic mode). Correct me if I am wrong. Thanks a lot! > > > + if (!kvm_apic_logical_map_valid(map)) { > > + WARN_ON_ONCE(1); > > Here, the guest can trigger it by setting a few APICs in flat mode and > others in cluster mode, for example. Oh, right, the logical map works only when the destination mode of all the vCPUs are the same. > > > + if (cid >= ARRAY_SIZE(map->logical_map)) { > > + WARN_ON_ONCE(1); > > In x2apic mode irq->dest_id could have bits 12..15 set. cid is gotten from bit 16 ..31 of the ldr (in apic_logical_id()), and in x2apic mode, ldr is constructed in kvm_apic_set_x2apic_id() as below: u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf)); So in fact, cid is (id >> 4), I cannot think of why cid can beyond 15. Do I miss something here? Thanks! Thanks, Feng > > Paolo -- 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
