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Date:   Tue, 12 Jul 2022 19:04:01 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Zhang Jiaming <jiaming@nfschina.com>
Cc:     pbonzini@redhat.com, vkuznets@redhat.com, wanpengli@tencent.com,
        jmattson@google.com, joro@8bytes.org, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        x86@kernel.org, hpa@zytor.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, liqiong@nfschina.com,
        renyu@nfschina.com
Subject: Re: [PATCH] KVM: LAPIC: Fix a spelling mistake in comments
Message-ID: <Ys3FodyfOxaT+NZU@google.com>
References: <20220701065558.9073-1-jiaming@nfschina.com>
 <Ys3Ex9GaoWAbNqF0@google.com>
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On Tue, Jul 12, 2022, Sean Christopherson wrote:
> On Fri, Jul 01, 2022, Zhang Jiaming wrote:
> ---
>  arch/x86/kvm/lapic.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 48740a235dee..ef5417d3ce95 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -830,13 +830,16 @@ static bool kvm_apic_match_physical_addr(struct kvm_lapic *apic, u32 mda)
>  		return mda == kvm_x2apic_id(apic);
> 
>  	/*
> -	 * Hotplug hack: Make LAPIC in xAPIC mode also accept interrupts as if
> -	 * it were in x2APIC mode.  Hotplugged VCPUs start in xAPIC mode and
> -	 * this allows unique addressing of VCPUs with APIC ID over 0xff.
> -	 * The 0xff condition is needed because writable xAPIC ID.

Doh, this won't apply on kvm/queue, I unintentionally generated this as a delta
on top of your patch.  I'll remedy that before testing and officially posting.

> +	 * Hotplug hack: Accept interrupts for vCPUs in xAPIC mode as if they
> +	 * were in x2APIC mode if the target APIC ID can't be encoded as an
> +	 * xAPIC ID.  This allows unique addressing of hotplugged vCPUs (which
> +	 * start in xAPIC mode) with an APIC ID that is unaddressable in xAPIC
> +	 * mode.  Match the x2APIC ID if and only if the target APIC ID can't
> +	 * be encoded in xAPIC to avoid spurious matches against a vCPU that
> +	 * changed its (addressable) xAPIC ID (which is writable).
>  	 */
> -	if (kvm_x2apic_id(apic) > 0xff && mda == kvm_x2apic_id(apic))
> -		return true;
> +	if (mda > 0xff)
> +		return mda == kvm_x2apic_id(apic);
> 
>  	return mda == kvm_xapic_id(apic);
>  }
> 
> base-commit: ba0d159dd8844469d4e4defff4985a7b80f956e9
> --
>