[Skiboot] [PATCH] core/pci: Fix criteria in pci_cfg_reg_filter()

[Alistair Popple]

Hi, looks ok to me. Feel free to add your pick of:

Reviewed-by: Alistair Popple <alistair at popple.id.au>
Acked-by: Alistair Popple <alistair at popple.id.au>

On Thu, 8 Sep 2016 03:42:00 PM Gavin Shan wrote:
> The criteria to match the filter according to PCI config register
> offset and length is strict one, meaning the accessed region should
> matches with the filter's tracking region. However, the code isn't
> correct enough - @len should be replaced with @pcrf->len.
> 
> The strict matching has to account for the length of current PCI
> config register access. We have to specify precise region through
> @start and @len in pci_virt_add_filter() when creating the filter.
> We lost flexibility. This changes the strict criteria to a relaxed
> one - the matched filter is returned when the accessed region is
> overlapped with the filter's region. With this change, the individual
> filter's handlers should validate the accessed (register) region if
> necessary.
> 
> Fixes: 85daa7f00c50 ("core/pci: Support virtual device")
> Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
> ---
>  core/pci-virt.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/core/pci-virt.c b/core/pci-virt.c
> index 570c6e8..b531470 100644
> --- a/core/pci-virt.c
> +++ b/core/pci-virt.c
> @@ -55,9 +55,14 @@ static struct pci_cfg_reg_filter *pci_virt_find_filter(
>  	if (!pvd || !len || start >= pvd->cfg_size)
>  		return NULL;
>  
> +	/* Return filter if there is overlapped region. We don't
> +	 * require strict matching for more flexibility. It also
> +	 * means the associated handler should validate the register
> +	 * offset and length.
> +	 */
>  	list_for_each(&pvd->pcrf, pcrf, link) {
> -		if (start >= pcrf->start &&
> -		    (start + len) <= (pcrf->start + len))
> +		if (start < (pcrf->start + pcrf->len) &&
> +		    (start + len) > pcrf->start)
>  			return pcrf;
>  	}
>  
>