From: Avi Kivity <avi@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org
Subject: Re: [PATCH v2 3/3] KVM: Non-atomic interrupt injection
Date: Wed, 21 Jul 2010 08:37:26 +0300 [thread overview]
Message-ID: <4C468796.4060700@redhat.com> (raw)
In-Reply-To: <20100721005533.GA9989@amt.cnet>
On 07/21/2010 03:55 AM, Marcelo Tosatti wrote:
>
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -4709,6 +4709,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>> if (unlikely(r))
>> goto out;
>>
>> + inject_pending_event(vcpu);
>> +
>> + /* enable NMI/IRQ window open exits if needed */
>> + if (vcpu->arch.nmi_pending)
>> + kvm_x86_ops->enable_nmi_window(vcpu);
>> + else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
>> + kvm_x86_ops->enable_irq_window(vcpu);
>> +
>> + if (kvm_lapic_enabled(vcpu)) {
>> + update_cr8_intercept(vcpu);
>> + kvm_lapic_sync_to_vapic(vcpu);
>> + }
>> +
>> preempt_disable();
>>
>> kvm_x86_ops->prepare_guest_switch(vcpu);
>> @@ -4727,23 +4740,11 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>> smp_wmb();
>> local_irq_enable();
>> preempt_enable();
>> + kvm_x86_ops->cancel_injection(vcpu);
>> r = 1;
>> goto out;
>> }
>>
>> - inject_pending_event(vcpu);
>> -
>> - /* enable NMI/IRQ window open exits if needed */
>> - if (vcpu->arch.nmi_pending)
>> - kvm_x86_ops->enable_nmi_window(vcpu);
>> - else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
>> - kvm_x86_ops->enable_irq_window(vcpu);
>> -
>> - if (kvm_lapic_enabled(vcpu)) {
>> - update_cr8_intercept(vcpu);
>> - kvm_lapic_sync_to_vapic(vcpu);
>> - }
>> -
>> srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
>>
>> kvm_guest_enter();
>>
> This breaks
>
> int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu)
> {
> struct kvm_lapic *apic = vcpu->arch.apic;
> int highest_irr;
>
> /* This may race with setting of irr in __apic_accept_irq() and
> * value returned may be wrong, but kvm_vcpu_kick() in
> * __apic_accept_irq
> * will cause vmexit immediately and the value will be
> * recalculated
> * on the next vmentry.
> */
>
> (also valid for nmi_pending and PIC). Can't simply move
> atomic_set(guest_mode, 1) in preemptible section as that would make it
> possible for kvm_vcpu_kick to IPI stale vcpu->cpu.
>
Right. Can fix by adding a kvm_make_request() to force the retry loop.
> Also should undo vmx.rmode.* ?
>
Elaborate?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-07-21 5:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-20 13:17 [PATCH v2 0/3] Nonatomic interrupt injection Avi Kivity
2010-07-20 13:17 ` [PATCH v2 1/3] KVM: VMX: Split up vmx_complete_interrupts() Avi Kivity
2010-07-20 13:17 ` [PATCH v2 2/3] KVM: VMX: Parameterize vmx_complete_interrupts() for both exit and entry Avi Kivity
2010-07-20 13:17 ` [PATCH v2 3/3] KVM: Non-atomic interrupt injection Avi Kivity
2010-07-21 0:55 ` Marcelo Tosatti
2010-07-21 5:37 ` Avi Kivity [this message]
2010-07-21 16:27 ` Marcelo Tosatti
2010-07-21 18:22 ` Avi Kivity
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