RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

[Wu, Feng]

> -----Original Message-----
> From: rkrcmar@xxxxxxxxxx [mailto:rkrcmar@xxxxxxxxxx]
> Sent: Friday, January 22, 2016 1:21 AM
> To: Wu, Feng <feng.wu@xxxxxxxxx>
> Cc: Yang Zhang <yang.zhang.wz@xxxxxxxxx>; pbonzini@xxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-
> priority interrupts



> > Oh, I didn't notice 'ret' is initialized to true, I thought it was initialized
> > to false like another function, I should add a "ret = false' here. We should
> > failed to inject the interrupt since hardware disabled LAPIC is found.
> 
> 'ret = true' is the better one.  We know that the interrupt is not
> deliverable [1], so there's no point in trying to deliver with the slow
> path.  We behave similarly when the interrupt targets a single disabled
> APIC.

Oh, yes, you are right, Thanks a lot!

Thanks,
Feng

> 
> ---
> 1: Well ... it's possible that slowpath would deliver it thanks to
>    different handling of disabled APICs, but it's undefined behavior,
>    so it doesn't matter matter if we don't try.