* [PATCH] KVM: X86: Fix loss of pending INIT due to race
@ 2017-07-30 9:42 Wanpeng Li
2017-08-01 16:27 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Wanpeng Li @ 2017-07-30 9:42 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: Paolo Bonzini, Radim Krčmář, Wanpeng Li
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 not touching INIT pending if INIT is not latched
which in SMM and just restoring the latched INIT after SET_VCPU_EVENTS.
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>
---
arch/x86/kvm/x86.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a4c84d..eaca86d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3164,12 +3164,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
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);
- else
- clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
- }
+ if (events->smi.latched_init && lapic_in_kernel(vcpu))
+ set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
}
kvm_make_request(KVM_REQ_EVENT, vcpu);
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: X86: Fix loss of pending INIT due to race
2017-07-30 9:42 [PATCH] KVM: X86: Fix loss of pending INIT due to race Wanpeng Li
@ 2017-08-01 16:27 ` Paolo Bonzini
2017-08-01 22:43 ` Wanpeng Li
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2017-08-01 16:27 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel, kvm; +Cc: Radim Krčmář, Wanpeng Li
On 30/07/2017 11:42, Wanpeng Li wrote:
> 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 not touching INIT pending if INIT is not latched
> which in SMM and just restoring the latched INIT after SET_VCPU_EVENTS.
>
> 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>
> ---
> arch/x86/kvm/x86.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1a4c84d..eaca86d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3164,12 +3164,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
> 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);
> - else
> - clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
> - }
> + if (events->smi.latched_init && lapic_in_kernel(vcpu))
> + set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
All this block:
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);
else
clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
}
only applies if you're in SMM, so perhaps you can move it under
if (events->smi.smm)
?
Paolo
> }
>
> kvm_make_request(KVM_REQ_EVENT, vcpu);
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: X86: Fix loss of pending INIT due to race
2017-08-01 16:27 ` Paolo Bonzini
@ 2017-08-01 22:43 ` Wanpeng Li
0 siblings, 0 replies; 3+ messages in thread
From: Wanpeng Li @ 2017-08-01 22:43 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, Radim Krčmář, Wanpeng Li
2017-08-02 0:27 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> On 30/07/2017 11:42, Wanpeng Li wrote:
>> 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 not touching INIT pending if INIT is not latched
>> which in SMM and just restoring the latched INIT after SET_VCPU_EVENTS.
>>
>> 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>
>> ---
>> arch/x86/kvm/x86.c | 8 ++------
>> 1 file changed, 2 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 1a4c84d..eaca86d 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3164,12 +3164,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
>> 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);
>> - else
>> - clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
>> - }
>> + if (events->smi.latched_init && lapic_in_kernel(vcpu))
>> + set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
>
> All this block:
>
> 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);
> else
> clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
> }
>
> only applies if you're in SMM, so perhaps you can move it under
>
> if (events->smi.smm)
>
> ?
Good point, I will do it in v2.
Regards,
Wanpeng Li
>
> Paolo
>
>> }
>>
>> kvm_make_request(KVM_REQ_EVENT, vcpu);
>>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2017-07-30 9:42 [PATCH] KVM: X86: Fix loss of pending INIT due to race Wanpeng Li
2017-08-01 16:27 ` Paolo Bonzini
2017-08-01 22:43 ` Wanpeng Li
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