linux-kernel - Re: [PATCH v2] cxl: Check for invalid addresses returned from translation functions on errors

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Message-ID: <aV5LdGD8lQm7AYK3@rric.localdomain>
Date: Wed, 7 Jan 2026 13:03:00 +0100
From: Robert Richter <rrichter@....com>
To: Alison Schofield <alison.schofield@...el.com>
Cc: Davidlohr Bueso <dave@...olabs.net>,
	Jonathan Cameron <jonathan.cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Dan Williams <dan.j.williams@...el.com>, linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] cxl: Check for invalid addresses returned from
 translation functions on errors

On 06.01.26 10:42:36, Alison Schofield wrote:
> On Tue, Jan 06, 2026 at 06:23:58PM +0100, Robert Richter wrote:

> > @@ -3207,8 +3220,13 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
> >  		cxled = p->targets[i];
> >  		if (cxled->pos != pos)
> >  			continue;
> > +
> > +		dpa = cxl_dpa_resource_start(cxled);
> 
> We want to return -ENXIO, not 0 in this case.
> So jump out here immediately - right?
> 
> 		if (dpa == REsOURCE_SIZE_MAX)
> 			return -ENXIO;

The users of region_offset_to_dpa_result() handle the
RESOURCE_SIZE_MAX case. For that reason the dpa is not checked here.
I did not want to change the function interface with that fix.

Thanks for review.

-Robert

> 
> 
> > +		if (dpa != RESOURCE_SIZE_MAX)
> > +			dpa += dpa_offset;
> > +
> >  		result->cxlmd = cxled_to_memdev(cxled);
> > -		result->dpa = cxl_dpa_resource_start(cxled) + dpa_offset;
> > +		result->dpa = dpa;
> >  
> >  		return 0;
> >  	}