Re: [PATCH 05/18] cxl/region: Add volatile region creation support

[Gregory Price <gregory.price@memverge.com>]

On Sun, Feb 05, 2023 at 05:02:56PM -0800, Dan Williams wrote:
> Expand the region creation infrastructure to enable 'ram'
> (volatile-memory) regions. The internals of create_pmem_region_store()
> and create_pmem_region_show() are factored out into helpers
> __create_region() and __create_region_show() for the 'ram' case to
> reuse.
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  
[...]
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 8566451cb22f..47e450c3a5a9 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -294,6 +294,7 @@ static struct attribute *cxl_decoder_root_attrs[] = {
>  	&dev_attr_cap_type3.attr,
>  	&dev_attr_target_list.attr,
>  	SET_CXL_REGION_ATTR(create_pmem_region)
> +	SET_CXL_REGION_ATTR(create_ram_region)
>  	SET_CXL_REGION_ATTR(delete_region)
>  	NULL,
>  };
> @@ -305,6 +306,13 @@ static bool can_create_pmem(struct cxl_root_decoder *cxlrd)
>  	return (cxlrd->cxlsd.cxld.flags & flags) == flags;
>  }
>  
> +static bool can_create_ram(struct cxl_root_decoder *cxlrd)
> +{
> +	unsigned long flags = CXL_DECODER_F_TYPE3 | CXL_DECODER_F_RAM;
> +
> +	return (cxlrd->cxlsd.cxld.flags & flags) == flags;
> +}
> +

does this collide with either CXL_DECODE_F_ENABLE or CXL_DECODER_F_AUTO?

I think obviously if it's already enabled creating new regions in a
decoder doesn't make sense, but if F_AUTO is set, does that imply
the region settings cannot be changed?