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Subject[PATCH v2] KVM: X86: Fix loss of pending INIT due to race
Date
From: Wanpeng Li <wanpeng.li@hotmail.com>

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>
---
v1 -> v2:
* move the stuff under if (events->smi_smm)

arch/x86/kvm/x86.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a4c84d..839b5dad6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3160,15 +3160,18 @@ 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);
+ }
}
}

--
2.7.4
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