linux-kernel - Re: [PATCH 3/3] KVM: x86: do not scan IRR twice on APICv vmentry

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Message-ID: <993cab93-393e-b850-9bb5-db21c98f03e9@redhat.com>
Date:   Fri, 14 Oct 2016 09:45:57 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yang Zhang <yang.zhang.wz@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     feng.wu@...el.com, mst@...hat.com, rkrcmar@...hat.com
Subject: Re: [PATCH 3/3] KVM: x86: do not scan IRR twice on APICv vmentry



On 14/10/2016 09:32, Yang Zhang wrote:
>>
>> -void __kvm_apic_update_irr(u32 *pir, void *regs)
>> +int __kvm_apic_update_irr(u32 *pir, void *regs)
>>  {
>> -    u32 i, pir_val;
>> +    u32 i, vec;
>> +    u32 pir_val, irr_val;
>> +    int max_irr = -1;
>>
>> -    for (i = 0; i <= 7; i++) {
>> +    for (i = vec = 0; i <= 7; i++, vec += 32) {
> 
> how about ignore the first 32 vectors since they cannot be used as
> normal interrupt except nmi interrupt which is special handled.

I think that, while they should not be used as normal interrupts,
there's nothing that prevents you from misusing them as normal interrupts.

Paolo