Gleb Natapov wrote on 2013-04-08:
> On Mon, Apr 08, 2013 at 11:21:34AM +0000, Zhang, Yang Z wrote:
>> Gleb Natapov wrote on 2013-04-07:
>>> On Sun, Apr 07, 2013 at 01:16:51PM +0000, Zhang, Yang Z wrote:
>>>> Gleb Natapov wrote on 2013-04-07:
>>>>> On Sun, Apr 07, 2013 at 01:05:02PM +0000, Zhang, Yang Z wrote:
>>>>>> Gleb Natapov wrote on 2013-04-07:
>>>>>>> On Sun, Apr 07, 2013 at 12:39:32PM +0000, Zhang, Yang Z wrote:
>>>>>>>> Gleb Natapov wrote on 2013-04-07:
>>>>>>>>> On Sun, Apr 07, 2013 at 02:30:15AM +0000, Zhang, Yang Z wrote:
>>>>>>>>>> Gleb Natapov wrote on 2013-04-04:
>>>>>>>>>>> On Mon, Apr 01, 2013 at 08:40:13AM +0800, Yang Zhang wrote:
>>>>>>>>>>>> From: Yang Zhang <yang.z.zh...@intel.com>
>>>>>>>>>>>>
>>>>>>>>>>>> Signed-off-by: Yang Zhang <yang.z.zh...@intel.com>
>>>>>>>>>>>> ---
>>>>>>>>>>>> arch/x86/kvm/lapic.c | 9 +++++++++ arch/x86/kvm/lapic.h |
>>>>>>>>>>>> 2 ++ virt/kvm/ioapic.c | 43
>>>>>>>>>>>> +++++++++++++++++++++++++++++++++++++++++++
>>>>>>>>>>>> virt/kvm/ioapic.h | 1 + 4 files changed, 55 insertions(+), 0
>>>>>>>>>>>> deletions(-)
>>>>>>>>>>>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>>>>>>>>>>>> index 96ab160..9c041fa 100644
>>>>>>>>>>>> --- a/arch/x86/kvm/lapic.c
>>>>>>>>>>>> +++ b/arch/x86/kvm/lapic.c
>>>>>>>>>>>> @@ -94,6 +94,14 @@ static inline int apic_test_vector(int vec,
> void
>>>>>>> *bitmap)
>>>>>>>>>>>> return test_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
>>>>>>>>>>>> }
>>>>>>>>>>>> +bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector)
>>>>>>>>>>>> +{
>>>>>>>>>>>> + struct kvm_lapic *apic = vcpu->arch.apic;
>>>>>>>>>>>> +
>>>>>>>>>>>> + return apic_test_vector(vector, apic->regs + APIC_ISR) ||
>>>>>>>>>>>> + apic_test_vector(vector, apic->regs + APIC_IRR);
>>>>>>>>>>>> +}
>>>>>>>>>>>> +
>>>>>>>>>>>> static inline void apic_set_vector(int vec, void *bitmap)
>>>>>>>>>>>> {
>>>>>>>>>>>> set_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
>>>>>>>>>>>> @@ -1665,6 +1673,7 @@ void
> kvm_apic_post_state_restore(struct
>>>>>>>>> kvm_vcpu
>>>>>>>>>>> *vcpu,
>>>>>>>>>>>> apic->highest_isr_cache = -1;
>>>>>>>>>>>> kvm_x86_ops->hwapic_isr_update(vcpu->kvm,
>>>>>>>>>>>> apic_find_highest_isr(apic));
>>>>>>>>>>>> kvm_make_request(KVM_REQ_EVENT, vcpu);
>>>>>>>>>>>> + kvm_rtc_irq_restore(vcpu); }
>>>>>>>>>>>>
>>>>>>>>>>>> void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
>>>>>>>>>>>> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
>>>>>>>>>>>> index 967519c..004d2ad 100644
>>>>>>>>>>>> --- a/arch/x86/kvm/lapic.h
>>>>>>>>>>>> +++ b/arch/x86/kvm/lapic.h
>>>>>>>>>>>> @@ -170,4 +170,6 @@ static inline bool
>>> kvm_apic_has_events(struct
>>>>>>>>>>> kvm_vcpu *vcpu)
>>>>>>>>>>>> return vcpu->arch.apic->pending_events;
>>>>>>>>>>>> }
>>>>>>>>>>>> +bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
>>>>>>>>>>>> +
>>>>>>>>>>>> #endif
>>>>>>>>>>>> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
>>>>>>>>>>>> index 8664812..0b12b17 100644
>>>>>>>>>>>> --- a/virt/kvm/ioapic.c
>>>>>>>>>>>> +++ b/virt/kvm/ioapic.c
>>>>>>>>>>>> @@ -90,6 +90,47 @@ static unsigned long
>>> ioapic_read_indirect(struct
>>>>>>>>>>> kvm_ioapic *ioapic,
>>>>>>>>>>>> return result;
>>>>>>>>>>>> }
>>>>>>>>>>>> +static void rtc_irq_reset(struct kvm_ioapic *ioapic) +{
>>>>>>>>>>>> + ioapic->rtc_status.pending_eoi = 0;
>>>>>>>>>>>> + bitmap_zero(ioapic->rtc_status.dest_map, KVM_MAX_VCPUS); +}
>>>>>>>>>>>> + +static void rtc_irq_restore(struct kvm_ioapic *ioapic) +{
>>>>>>>>>>>> + struct kvm_vcpu *vcpu; + int vector, i, pending_eoi = 0;
>>>>>>>>>>>> +
>>>>>>>>>>>> + if (RTC_GSI >= IOAPIC_NUM_PINS) + return; + +
>>>>>>>>>>>> vector =
>>>>>>>>>>>> ioapic->redirtbl[RTC_GSI].fields.vector;
>>>>>>>>>>>> + kvm_for_each_vcpu(i, vcpu, ioapic->kvm) { + if
>>>>>>>>>>>> (kvm_apic_pending_eoi(vcpu, vector)) { +
>>>>>>>>>>>> pending_eoi++;
>>>>>>>>>>>> + __set_bit(vcpu->vcpu_id,
>>>>> ioapic->rtc_status.dest_map);
>>>>>>>>>>> You should cleat dest_map at the beginning to get rid of stale bits.
>>>>>>>>>> I thought kvm_set_ioapic is called only after save/restore or
> migration.
>>>>> And
>>>>>>> the
>>>>>>>>> ioapic should be reset successfully before call it. So the
>>>>>>>>> dest_map is empty before call rtc_irq_restore().
>>>>>>>>>> But it is possible kvm_set_ioapic is called beside save/restore or
>>>>>>>>>> migration. Right?
>>>>>>>>>>
>>>>>>>>> First of all userspace should not care when it calls
>>>>>>>>> kvm_set_ioapic() the kernel need to do the right thing. Second,
>>>>>>>>> believe it or not, kvm_ioapic_reset() is not called during
>>>>>>>>> system reset. Instead userspace reset it by calling
>>>>>>>>> kvm_set_ioapic() with ioapic state after reset.
>>>>>>>> Ok. I see. As the logic you suggested, it will clear dest_map if no
>>>>>>>> pending eoi in vcpu, so we don't need to do it again.
>>>>>>>>
>>>>>>> You again rely on userspace doing thing in certain manner. What is
>>>>>>> set_lapic() is never called? Kernel internal state have to be correct
>>>>>>> after each ioctl call.
>>>>>> Sorry. I cannot figure out what's the problem if don't clear dest_map?
>>>>>> Can you elaborate it?
>>>>>>
>>>>> What is not obvious about it? If there is a bit in dest_map that should
>>>>> be cleared after rtc_irq_restore() it will not.
>>>> Why it will not? If new_val is false, and the old_val is true.
>>>> __clear_bit() will clear the dest_map. Am I wrong?
>>>>
>>> Ah, yes with new logic since we go over all vcpus and calculate new
>>> value for each one in theory it should be fine, but if we add cpu
>>> destruction this will be no longer true.
>>>
>>>> new_val = kvm_apic_pending_eoi(vcpu, vector);
>>> Which reminds me there are more bugs in the current code. It is not
>>> enough to call kvm_apic_pending_eoi() to check the new value. You need to
>>> see if the entry is masked and vcpu is the destination of the interrupt too.
>> No. kvm_apic_pending_eoi() is the right way. IOAPIC entry may change
>> after vcpu received it before issue EOI, and we should not rely on the
>> entry. For example: vcpu A received the interrupt, pending in IRR mask
>> entry migration happened
>>
>> The only problem is we may account the interrupt from non-IOAPIC(from IPI)
> into RTC interrupt. But it's ok, we will clear pending_eoi in EOI regardless
> of
> source.
>>
> With apicv this EOI may never come. We have to at least check that the vcpu
> is a destination for the interrupt.
You are right. This is necessary/
Best regards,
Yang
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