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KVM: X86: Fix loss of pending INIT due to race

Browse source 
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>
This commit is contained in:
Wanpeng Li 2017-08-01 16:05:25 -07:00 • committed by Radim Krčmář
parent 337c017ccd
commit f4ef191086
1 changed files with 11 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
arch/x86/kvm/x86.c
View file

@ -3159,15 +3159,18 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
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);
}
}
}