> -----Original Message-----
> From: Paolo Bonzini [mailto:[email protected]]
> Sent: Friday, September 18, 2015 12:00 AM
> To: Radim Krčmář
> Cc: Wu, Feng; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> 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
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