> -----Original Message----- > From: Paolo Bonzini [mailto:pbonzini@xxxxxxxxxx] > Sent: Friday, September 18, 2015 12:00 AM > To: Radim Krčmář > Cc: Wu, Feng; alex.williamson@xxxxxxxxxx; joro@xxxxxxxxxx; > mtosatti@xxxxxxxxxx; 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 17:58, Radim Krčmář wrote: > > For interrupts from MSI and IOxAPIC: > > - Flat logical interrupts are delivered as if we had natural > > (CPU0<->bit0, CPU1<->bit1, ...) flat logical xAPIC for first 8 VCPUs. > > - Cluster logical doesn't work much, it's interpreted like flat logical. > > I didn't care about xAPIC cluster because Linux, the sole user of our > > paravirtualized x2APIC, doesn't configure it. > > > > I'll paste kvm_apic_mda() source for better explanation: > > > > static u32 kvm_apic_mda(unsigned int dest_id, struct kvm_lapic *source, > > struct kvm_lapic > *target) > > { > > bool ipi = source != NULL; > > bool x2apic_mda = apic_x2apic_mode(ipi ? source : target); > > > > if (!ipi && dest_id == APIC_BROADCAST && x2apic_mda) > > return X2APIC_BROADCAST; > > > > return x2apic_mda ? dest_id : SET_APIC_DEST_FIELD(dest_id); > > } > > > > MSI/IOxAPIC interrupt means that source is NULL and if the target is in > > x2APIC mode, the original 'dest_id' is returned as mda => a flat logical > > xAPIC to 0x0f will get interpreted as (cluster) logical x2APIC 0xf in > > kvm_apic_match_logical_addr(). > > xAPIC address are only 8 bit long so they always get delivered to x2APIC > > cluster 0, where first 16 bits work like xAPIC flat logical mode. > > Ok, I was wondering whether this was the correct interpretation. Thanks! Paolo, I don't think Radim clarify your concern, right? Since mda is 8-bit, it is wrong with mda >> 16, this is your concern, right? Thanks, Feng > > Paolo ��.n��������+%������w��{.n�����o�^n�r������&��z�ޗ�zf���h���~����������_��+v���)ߣ�
