Re: [PATCH v3 5/8] KVM: Recalculate destination vcpu map

[Gleb Natapov <gleb@redhat.com>]

On Mon, Mar 18, 2013 at 08:47:19PM +0800, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@Intel.com>
> 
> Update destination vcpu map when ioapic entry or apic(id, ldr, dfr) is changed
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> ---
>  virt/kvm/ioapic.c |   40 ++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 38 insertions(+), 2 deletions(-)
> 
> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
> index 4296116..329efe1 100644
> --- a/virt/kvm/ioapic.c
> +++ b/virt/kvm/ioapic.c
> @@ -87,6 +87,38 @@ static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
>  	return result;
>  }
>  
> +#ifdef CONFIG_X86
> +static void rtc_irq_get_dest_vcpu(struct kvm_ioapic *ioapic, int irq)
> +{
> +	union kvm_ioapic_redirect_entry *entry = &ioapic->redirtbl[irq];
> +	struct kvm_lapic_irq irqe;
> +
> +	if (irq != 8 || entry->fields.mask)
> +		return;
> +
> +	spin_lock(&ioapic->lock);
How does this not deadlock? The is called from kvm_scan_ioapic_entry()
and kvm_scan_ioapic_entry() is called from ioapic_write_indirect() with
the lock already taken. You should handle that the same way we handle
eoibitmap recalculation: signal vcpu and calculate there.

> +	irqe.dest_id = entry->fields.dest_id;
> +	irqe.vector = entry->fields.vector;
> +	irqe.dest_mode = entry->fields.dest_mode;
> +	irqe.trig_mode = entry->fields.trig_mode;
> +	irqe.delivery_mode = entry->fields.delivery_mode << 8;
> +	irqe.level = 1;
> +	irqe.shorthand = 0;
> +
> +	bitmap_zero(ioapic->rtc_status.vcpu_map, KVM_MAX_VCPUS);
> +
> +	kvm_get_dest_vcpu(ioapic->kvm, &irqe, ioapic->rtc_status.vcpu_map);
> +	spin_unlock(&ioapic->lock);
> +}
> +
> +#else
> +
> +static void rtc_irq_get_dest_vcpu(struct kvm_ioapic *ioapic, int irq)
> +{
> +	return;
> +}
> +#endif
> +
>  static int ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx)
>  {
>  	union kvm_ioapic_redirect_entry *pent;
> @@ -147,9 +179,13 @@ void kvm_scan_ioapic_entry(struct kvm *kvm)
>  {
>  	struct kvm_ioapic *ioapic = kvm->arch.vioapic;
>  
> -	if (!kvm_apic_vid_enabled(kvm) || !ioapic)
> +	if (!ioapic)
>  		return;
> -	kvm_make_update_eoibitmap_request(kvm);
> +
> +	rtc_irq_get_dest_vcpu(ioapic, 8);
> +
> +	if (kvm_apic_vid_enabled(kvm))
> +		kvm_make_update_eoibitmap_request(kvm);
>  }
>  
>  static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
> -- 
> 1.7.1

--
			Gleb.