Re: [PATCH 1/4] cxl/list: Fix filtering RCDs

[Dave Jiang <dave.jiang@intel.com>]

On 4/24/23 12:59 PM, Dan Williams wrote:
> Attempts to filter by memdev fail when the memdev is an RCD (RCH topology):
> 
>      # cxl list -BEM -m 11
>        Warning: no matching devices found
> 
>      [
>      ]
> 
> This is caused by VH topology assumption where an intervening host-bridge
> port is expected between the root CXL port and the endpoint. In an RCH
> topology an endpoint is integrated in the host-bridge.
> 
> Search for endpoints directly attached to the root:
> 
>      # cxl list -BEMu -m 11
>      {
>        "bus":"root3",
>        "provider":"cxl_test",
>        "endpoints:root3":[
>          {
>            "endpoint":"endpoint22",
>            "host":"mem11",
>            "depth":1,
>            "memdev":{
>              "memdev":"mem11",
>              "ram_size":"2.00 GiB (2.15 GB)",
>              "serial":"0xa",
>              "numa_node":0,
>              "host":"cxl_rcd.10"
>            }
>          }
>        ]
>      }
> 
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>   cxl/lib/libcxl.c |   19 ++++++++++++++++---
>   1 file changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index 59e5bdbcc750..e6c94d623303 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -1457,8 +1457,9 @@ CXL_EXPORT int cxl_memdev_enable(struct cxl_memdev *memdev)
>   	return 0;
>   }
>   
> -static struct cxl_endpoint *cxl_port_find_endpoint(struct cxl_port *parent_port,
> -						   struct cxl_memdev *memdev)
> +static struct cxl_endpoint *
> +cxl_port_recurse_endpoint(struct cxl_port *parent_port,
> +			  struct cxl_memdev *memdev)
>   {
>   	struct cxl_endpoint *endpoint;
>   	struct cxl_port *port;
> @@ -1468,7 +1469,7 @@ static struct cxl_endpoint *cxl_port_find_endpoint(struct cxl_port *parent_port,
>   			if (strcmp(cxl_endpoint_get_host(endpoint),
>   				   cxl_memdev_get_devname(memdev)) == 0)
>   				return endpoint;
> -		endpoint = cxl_port_find_endpoint(port, memdev);
> +		endpoint = cxl_port_recurse_endpoint(port, memdev);
>   		if (endpoint)
>   			return endpoint;
>   	}
> @@ -1476,6 +1477,18 @@ static struct cxl_endpoint *cxl_port_find_endpoint(struct cxl_port *parent_port,
>   	return NULL;
>   }
>   
> +static struct cxl_endpoint *cxl_port_find_endpoint(struct cxl_port *parent_port,
> +						   struct cxl_memdev *memdev)
> +{
> +	struct cxl_endpoint *endpoint;
> +
> +	cxl_endpoint_foreach(parent_port, endpoint)
> +		if (strcmp(cxl_endpoint_get_host(endpoint),
> +			   cxl_memdev_get_devname(memdev)) == 0)
> +			return endpoint;
> +	return cxl_port_recurse_endpoint(parent_port, memdev);
> +}
> +
>   CXL_EXPORT struct cxl_endpoint *
>   cxl_memdev_get_endpoint(struct cxl_memdev *memdev)
>   {
> 
>