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Date:   Tue, 15 Feb 2022 11:27:13 +0800
From:   Chao Gao <chao.gao@intel.com>
To:     Sean Christopherson <seanjc@google.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Zeng Guang <guang.zeng@intel.com>,
        Maxim Levitsky <mlevitsk@redhat.com>
Subject: Re: [PATCH 09/11] KVM: x86: Treat x2APIC's ICR as a 64-bit register,
 not two 32-bit regs
Message-ID: <20220215032712.GB28478@gao-cwp>
References: <20220204214205.3306634-1-seanjc@google.com>
 <20220204214205.3306634-10-seanjc@google.com>
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> 	case APIC_SELF_IPI:
>-		if (apic_x2apic_mode(apic)) {
>-			kvm_lapic_reg_write(apic, APIC_ICR,
>-					    APIC_DEST_SELF | (val & APIC_VECTOR_MASK));
>-		} else
>+		if (apic_x2apic_mode(apic))
>+			kvm_x2apic_icr_write(apic, APIC_DEST_SELF | (val & APIC_VECTOR_MASK));
>+		else

The original code looks incorrect. Emulating writes to SELF_IPI by writes to
ICR has an unwanted side-effect: the value of ICR in vAPIC page gets changed.

It is better to use kvm_apic_send_ipi() directly.