Re: [PATCH] qemu-kvm: reserve the low 24 gsi values

[Gleb Natapov <gleb@redhat.com>]

On Tue, Jul 21, 2009 at 06:57:42PM +0300, Michael S. Tsirkin wrote:
> reserve gsi 0 to 23 so that they won't be allocated for msi
> 
In the not so distant future we may want to support more then one
ioapic, so 23 will became 23*n where n is a number of ioapics. I prefer
to fix it by moving msi injection to its own ioctl. But for now may be
we can scan used_gsi_bitmap from the end during allocation of gsi for
msi?

> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> 
> ---
> 
> diff --git a/qemu-kvm.c b/qemu-kvm.c
> index c6c9fc6..f440b2d 100644
> --- a/qemu-kvm.c
> +++ b/qemu-kvm.c
> @@ -1613,10 +1613,12 @@ int kvm_get_irq_route_gsi(kvm_context_t kvm)
>  {
>  	int i, bit;
>  	uint32_t *buf = kvm->used_gsi_bitmap;
> +	uint32_t mask = 0xff000000;
>  
>  	/* Return the lowest unused GSI in the bitmap */
> -	for (i = 0; i < kvm->max_gsi / 32; i++) {
> -		bit = ffs(~buf[i]);
> +	for (i = 0; i < kvm->max_gsi / 32; i++) {
> +		bit = ffs(~buf[i] & mask);
> +		mask = 0xffffffff;
>  		if (!bit)
>  			continue;
>  

--
			Gleb.