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From:   Zeng Guang <guang.zeng@intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.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,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Kim Phillips <kim.phillips@amd.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Jethro Beekman <jethro@fortanix.com>,
        Kai Huang <kai.huang@intel.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org,
        Robert Hu <robert.hu@intel.com>, Gao Chao <chao.gao@intel.com>,
        Zeng Guang <guang.zeng@intel.com>
Subject: [PATCH 5/6] KVM: x86: Support interrupt dispatch in x2APIC mode with APIC-write VM exit
Date:   Fri, 16 Jul 2021 14:48:07 +0800
Message-Id: <20210716064808.14757-6-guang.zeng@intel.com>
In-Reply-To: <20210716064808.14757-1-guang.zeng@intel.com>
References: <20210716064808.14757-1-guang.zeng@intel.com>
Precedence: bulk

Since IA x86 platform introduce features of IPI virtualization and
User Interrupts, new behavior applies to the execution of WRMSR ICR
register that causes APIC-write VM exit instead of MSR-write VM exit
in x2APIC mode.

This requires KVM to emulate writing 64-bit value to offset 300H on
the virtual-APIC page(VICR) for guest running in x2APIC mode when
APIC-wrtie VM exit occurs. Prevoisely KVM doesn't consider this
situation as CPU never produce APIC-write VM exit in x2APIC mode before.

Signed-off-by: Zeng Guang <guang.zeng@intel.com>
---
 arch/x86/kvm/lapic.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ba5a27879f1d..0b0f0ce96679 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2188,7 +2188,14 @@ void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset)
 	/* hw has done the conditional check and inst decode */
 	offset &= 0xff0;
 
-	kvm_lapic_reg_read(vcpu->arch.apic, offset, 4, &val);
+	if (apic_x2apic_mode(vcpu->arch.apic) && (offset == APIC_ICR)) {
+		u64 icr_val = *((u64 *)(vcpu->arch.apic->regs + offset));
+
+		kvm_lapic_reg_write(vcpu->arch.apic, APIC_ICR2, (u32)(icr_val>>32));
+		val = (u32)icr_val;
+	} else {
+		kvm_lapic_reg_read(vcpu->arch.apic, offset, 4, &val);
+	}
 
 	/* TODO: optimize to just emulate side effect w/o one more write */
 	kvm_lapic_reg_write(vcpu->arch.apic, offset, val);
-- 
2.25.1