From: Wanpeng Li <wanpeng.li@hotmail.com>
Date: Tue, 1 Aug 2017 16:05:25 -0700
Subject: KVM: X86: Fix loss of pending INIT due to race
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Patch-mainline: v4.13-rc4
Git-commit: f4ef19108608c81769db69976999d056c070a6f0
References: bsc#1077761

When SMP VM start, AP may lost INIT because of receiving INIT between
kvm_vcpu_ioctl_x86_get/set_vcpu_events.

       vcpu 0                             vcpu 1
                                   kvm_vcpu_ioctl_x86_get_vcpu_events
                                     events->smi.latched_init = 0
  send INIT to vcpu1
    set vcpu1's pending_events
                                   kvm_vcpu_ioctl_x86_set_vcpu_events
                                      if (events->smi.latched_init == 0)
                                        clear INIT in pending_events

This patch fixes it by just update SMM related flags if we are in SMM.

Thanks Peng Hao for the report and original commit message.

Reported-by: Peng Hao <peng.hao2@zte.com.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Acked-by: Alexander Graf <agraf@suse.de>
---
 arch/x86/kvm/x86.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3160,15 +3160,18 @@
 		kvm_set_hflags(vcpu, hflags);
 
 		vcpu->arch.smi_pending = events->smi.pending;
-		if (events->smi.smm_inside_nmi)
-			vcpu->arch.hflags |= HF_SMM_INSIDE_NMI_MASK;
-		else
-			vcpu->arch.hflags &= ~HF_SMM_INSIDE_NMI_MASK;
-		if (lapic_in_kernel(vcpu)) {
-			if (events->smi.latched_init)
-				set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
+
+		if (events->smi.smm) {
+			if (events->smi.smm_inside_nmi)
+				vcpu->arch.hflags |= HF_SMM_INSIDE_NMI_MASK;
 			else
-				clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
+				vcpu->arch.hflags &= ~HF_SMM_INSIDE_NMI_MASK;
+			if (lapic_in_kernel(vcpu)) {
+				if (events->smi.latched_init)
+					set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
+				else
+					clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
+			}
 		}
 	}