Re: [PATCH v7 4/7] KVM: Add reset/restore rtc_status support

[Gleb Natapov <gleb@redhat.com>]

On Mon, Apr 01, 2013 at 08:40:13AM +0800, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@Intel.com>
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@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.

> +		}
> +	}
> +	ioapic->rtc_status.pending_eoi = pending_eoi;
> +}
> +
> +void kvm_rtc_irq_restore(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
> +	int vector;
> +
> +	if (!ioapic)
> +		return;
> +
Can this be called if ioapic == NULL?
Should check for if (RTC_GSI >= IOAPIC_NUM_PINS) here too.

> +	spin_lock(&ioapic->lock);
> +	vector = ioapic->redirtbl[RTC_GSI].fields.vector;
> +	if (kvm_apic_pending_eoi(vcpu, vector)) {
> +		__set_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
> +		ioapic->rtc_status.pending_eoi++;
The bit may have been set already. The logic should be:

new_val = kvm_apic_pending_eoi(vcpu, vector)
old_val = set_bit(vcpu_id, dest_map)

if (new_val == old_val)
	return;

if (new_val) {
	__set_bit(vcpu_id, dest_map);
	pending_eoi++;
} else {
	__clear_bit(vcpu_id, dest_map);
	pending_eoi--;
}

The naming of above two functions are not good either. Call
them something like kvm_rtc_eoi_tracking_restore_all() and
kvm_rtc_eoi_tracking_restore_one().  And _all should call _one() for
each vcpu. Make __rtc_irq_eoi_tracking_restore_one() that does not
take ioapic lock and call it from kvm_rtc_eoi_tracking_restore_one()
surrounded by locks.

--
			Gleb.