linux-kernel - Re: [PATCH v2 4/4] KVM: ioapic: reinject pending interrupts on KVM_SET

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Date:	Mon, 24 Mar 2014 18:58:31 +0100
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org, gleb@...nel.org,
	mtosatti@...hat.com, alex.williamson@...hat.com,
	jan.kiszka@...mens.com
Subject: Re: [PATCH v2 4/4] KVM: ioapic: reinject pending interrupts on
 KVM_SET_IRQCHIP

2014-03-21 10:28+0100, Paolo Bonzini:
> After the previous patches, an interrupt whose bit is set in the IRR
> register will never be in the LAPIC's IRR and has never been injected
> on the migration source.  So inject it on the destination.
> 
> This fixes migration of Windows guests without HPET (they use the RTC
> to trigger the scheduler tick, and lose it after migration).
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
> 	v1->v2:
> 	use IOAPIC_NUM_PINS as a limit to for_each_set_bit
> 	remove debug printk
> 
>  virt/kvm/ioapic.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
> index 270f7fe73f39..d4b601547f1f 100644
> --- a/virt/kvm/ioapic.c
> +++ b/virt/kvm/ioapic.c
> @@ -212,6 +212,18 @@ out:
>  	return ret;
>  }
>  
> +static void kvm_ioapic_inject_all(struct kvm_ioapic *ioapic, unsigned long irr)
> +{
> +	u32 idx;
> +
> +	rtc_irq_eoi_tracking_reset(ioapic);
> +	for_each_set_bit(idx, &irr, IOAPIC_NUM_PINS)
> +		ioapic_set_irq(ioapic, idx, 1, true);
> +
> +	kvm_rtc_eoi_tracking_restore_all(ioapic);

(We shouldn't have RTC interrupt with pending EOI in irr, so the
 function could be independent.
 I'd prefer 'ioapic->irr = 0' here ...)

> +}
> +
> +
>  static void update_handled_vectors(struct kvm_ioapic *ioapic)
>  {
>  	DECLARE_BITMAP(handled_vectors, 256);
> @@ -612,9 +624,10 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
>  
>  	spin_lock(&ioapic->lock);
>  	memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
> +	ioapic->irr = 0;
>  	update_handled_vectors(ioapic);
>  	kvm_vcpu_request_scan_ioapic(kvm);
> -	kvm_rtc_eoi_tracking_restore_all(ioapic);
> +	kvm_ioapic_inject_all(ioapic, state->irr);
>  	spin_unlock(&ioapic->lock);
>  	return 0;
>  }
> -- 
> 1.8.3.1
> 
> --
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