netdev - Re: [PATCH v23 20/22] cxl: Avoid dax creation for accelerators

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Message-ID: <76556d1b-646c-477c-a315-33c3bb3cd981@amd.com>
Date: Wed, 11 Feb 2026 16:10:28 -0600
From: "Cheatham, Benjamin" <benjamin.cheatham@....com>
To: <alejandro.lucero-palau@....com>
CC: Alejandro Lucero <alucerop@....com>, Jonathan Cameron
	<Jonathan.Cameron@...wei.com>, Davidlohr Bueso <daves@...olabs.net>,
	<linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <edward.cree@....com>, <davem@...emloft.net>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>,
	<dave.jiang@...el.com>
Subject: Re: [PATCH v23 20/22] cxl: Avoid dax creation for accelerators

On 2/1/2026 9:54 AM, alejandro.lucero-palau@....com wrote:
> From: Alejandro Lucero <alucerop@....com>
> 
> By definition a type2 cxl device will use the host managed memory for
> specific functionality, therefore it should not be available to other
> uses.
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Davidlohr Bueso <daves@...olabs.net>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>
> ---
>  drivers/cxl/core/region.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 293e63dfef22..12df717cc881 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -4441,6 +4441,13 @@ static int cxl_region_probe(struct device *dev)
>  	if (rc)
>  		return rc;
>  
> +	/*
> +	 * HDM-D[B] (device-memory) regions have accelerator specific usage.
> +	 * Skip device-dax registration.
> +	 */
> +	if (cxlr->type == CXL_DECODER_DEVMEM)
> +		return 0;

Minor nit: Should probably move this to be the first thing in the function. It would save
having to acquire a lock in cxl_region_can_probe() above. Keep my reviewed-by either way,
it's really just a minor optimization.
> +
>  	/*
>  	 * From this point on any path that changes the region's state away from
>  	 * CXL_CONFIG_COMMIT is also responsible for releasing the driver.