Re: [PATCH 01/10] Change irq routing table to use gsi indexed array.

[Avi Kivity <avi@redhat.com>]

On 08/09/2009 03:41 PM, Gleb Natapov wrote:
> Use gsi indexed array instead of scanning all entries on each interrupt
> injection. Also maintain back mapping from irqchip/pin to gsi to speedup
> interrupt acknowledgment notifications.
>
> Signed-off-by: Gleb Natapov<gleb@redhat.com>
> ---
>   include/linux/kvm_host.h |   11 +++++-
>   virt/kvm/irq_comm.c      |   87 ++++++++++++++++++++++++---------------------
>   virt/kvm/kvm_main.c      |    1 -
>   3 files changed, 55 insertions(+), 44 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index f814512..a38f576 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -129,7 +129,14 @@ struct kvm_kernel_irq_routing_entry {
>   		} irqchip;
>   		struct msi_msg msi;
>   	};
> -	struct list_head link;
> +	struct hlist_node link;
> +};
> +
> +struct kvm_irq_routing_table {
> +	int chip[3][KVM_IOAPIC_NUM_PINS];
> +	struct kvm_kernel_irq_routing_entry *rt_entries;
> +	u32 max_gsi;
>    

That's the table size, no?  so call it nr_rt_entries to reflect that 
(max_* implies an off-by-one).

> +	struct hlist_head map[0];
>   };
>    

What's this? (comment explaining the type of data).

>
>   struct kvm {
> @@ -167,7 +174,7 @@ struct kvm {
>
>   	struct mutex irq_lock;
>   #ifdef CONFIG_HAVE_KVM_IRQCHIP
> -	struct list_head irq_routing; /* of kvm_kernel_irq_routing_entry */
>    

Like here.

> @@ -150,8 +152,9 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
>   	 * IOAPIC.  So set the bit in both. The guest will ignore
>   	 * writes to the unused one.
>   	 */
> -	list_for_each_entry(e,&kvm->irq_routing, link)
> -		if (e->gsi == irq) {
> +	irq_rt = kvm->irq_routing;
> +	if (irq<  irq_rt->max_gsi)
>    

irq here is int, so can overflow.  I think all paths are protected, but 
better to change irq to unsigned just in case.

> +		hlist_for_each_entry(e, n,&irq_rt->map[irq], link) {
>   			int r = e->set(e, kvm, sig_level);
>   			if (r<  0)
>   				continue;
> @@ -163,20 +166,15 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
>
>   void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
>   {
> -	struct kvm_kernel_irq_routing_entry *e;
>   	struct kvm_irq_ack_notifier *kian;
>   	struct hlist_node *n;
> -	unsigned gsi = pin;
> +	unsigned gsi;
>
>   	trace_kvm_ack_irq(irqchip, pin);
>
> -	list_for_each_entry(e,&kvm->irq_routing, link)
> -		if (e->type == KVM_IRQ_ROUTING_IRQCHIP&&
> -		    e->irqchip.irqchip == irqchip&&
> -		    e->irqchip.pin == pin) {
> -			gsi = e->gsi;
> -			break;
> -		}
> +	gsi = kvm->irq_routing->chip[irqchip][pin];
> +	if (gsi == -1)
> +		gsi = pin;
>    

Please separate the reverse map to a separate patch.

> +	new = kzalloc(sizeof(*new) + (max_gsi * sizeof(struct hlist_head)) +
> +		      (nr * sizeof(struct kvm_kernel_irq_routing_entry)),
> +		      GFP_KERNEL);
>    

Wow.


-- 
error compiling committee.c: too many arguments to function