Subject: Re: [PATCH v6 26/28] cxl: add function for obtaining region range

From: Zhi Wang <[email-masked]>
Date: Tue, 3 Dec 2024 20:53:55 +0200

On Mon, 2 Dec 2024 17:12:20 +0000
<[email-masked]> wrote:

> From: Alejandro Lucero <[email-masked]>
> 
> A CXL region struct contains the physical address to work with.
> 
> Add a function for getting the cxl region range to be used for mapping
> such memory range.
> 
> Signed-off-by: Alejandro Lucero <[email-masked]>
> ---
>  drivers/cxl/core/region.c | 15 +++++++++++++++
>  drivers/cxl/cxl.h         |  1 +
>  include/cxl/cxl.h         |  1 +
>  3 files changed, 17 insertions(+)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 5cb7991268ce..021e9b373cdd 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2667,6 +2667,21 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
>  	return ERR_PTR(rc);
>  }
>  
> +int cxl_get_region_range(struct cxl_region *region, struct range *range)
> +{
> +	if (!region)
> +		return -ENODEV;
> +

I am leaning towards having a WARN_ON_ONCE() above.

> +	if (!region->params.res)
> +		return -ENOSPC;
> +
> +	range->start = region->params.res->start;
> +	range->end = region->params.res->end;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_get_region_range, CXL);
> +
>  static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)
>  {
>  	return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index cc9e3d859fa6..32d2bd0520d4 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -920,6 +920,7 @@ void cxl_coordinates_combine(struct access_coordinate *out,
>  
>  bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
>  
> +int cxl_get_region_range(struct cxl_region *region, struct range *range);
>  /*
>   * Unit test builds overrides this to __weak, find the 'strong' version
>   * of these symbols in tools/testing/cxl/.
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 14be26358f9c..0ed9e32f25dd 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -65,4 +65,5 @@ struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>  				     bool no_dax);
>  
>  int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
> +int cxl_get_region_range(struct cxl_region *region, struct range *range);
>  #endif