From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 24 Feb 2022 14:53:36 +0000 (-0500)
Subject: KVM: x86: Do not change ICR on write to APIC_SELF_IPI
X-Git-Tag: v5.10.115~10
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a474ee5ececc19c764c718c76550c5650e54a3be;p=users%2Fdwmw2%2Flinux.git

KVM: x86: Do not change ICR on write to APIC_SELF_IPI

[ Upstream commit d22a81b304a27fca6124174a8e842e826c193466 ]

Emulating writes to SELF_IPI with a write to ICR has an unwanted side effect:
the value of ICR in vAPIC page gets changed.  The lists SELF_IPI as write-only,
with no associated MMIO offset, so any write should have no visible side
effect in the vAPIC page.

Reported-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index de11149e28e09..e45ebf0870b68 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2106,10 +2106,9 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 		break;
 
 	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_apic_send_ipi(apic, APIC_DEST_SELF | (val & APIC_VECTOR_MASK), 0);
+		else
 			ret = 1;
 		break;
 	default: