lkml.org 
[lkml]   [2017]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v3] KVM: LAPIC: Fix reentrancy issues with preempt notifiers
2017-07-25 15:25 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> On 25/07/2017 00:43, Wanpeng Li wrote:
>> - WARN_ON(!apic->lapic_timer.hv_timer_in_use);
>> + preempt_disable();
>> + /* The preempt notifier has called apic_timer_expired already */
>> + if (!apic->lapic_timer.hv_timer_in_use)
>> + goto out;
>> WARN_ON(swait_active(&vcpu->wq));
>> cancel_hv_timer(apic);
>> apic_timer_expired(apic);
>> +out:
>> + preempt_enable();
>
> If apic_timer_expired was called, and the timer is in periodic mode, it
> has already set the hv timer. Should the out label be really at the end
> of the function, after the timer is restarted? Otherwise you can call
> advance_periodic_timer_expiration twice.

I just send out v4 to fix it. Thanks for the review.

Regards,
Wanpeng Li

>
> Thanks,
>
> Paolo
>
>>
>> if (apic_lvtt_period(apic) && apic->lapic_timer.period) {
>> advance_periodic_target_expiration(apic);
>> @@ -1582,9 +1588,11 @@ void kvm_lapic_switch_to_sw_timer(struct kvm_vcpu *vcpu)
>> {
>> struct kvm_lapic *apic = vcpu->arch.apic;
>>
>> + preempt_disable();
>> /* Possibly the TSC deadline timer is not enabled yet */
>> if (apic->lapic_timer.hv_timer_in_use)
>> start_sw_timer(apic);
>> + preempt_enable();
>> }
>> EXPORT_SYMBOL_GPL(kvm_lapic_switch_to_sw_timer);
>

\
 
 \ /
  Last update: 2017-07-25 09:45    [W:0.082 / U:0.180 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site