linux-kernel - Re: [PATCH v1 15/29] cxl/region: Use an endpoint's SPA range to find a region

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Message-ID: <Z5zwQiic51BfULdd@rric.localdomain>
Date: Fri, 31 Jan 2025 16:46:10 +0100
From: Robert Richter <rrichter@....com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Davidlohr Bueso <dave@...olabs.net>, linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org, Gregory Price <gourry@...rry.net>,
	"Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>,
	Terry Bowman <terry.bowman@....com>
Subject: Re: [PATCH v1 15/29] cxl/region: Use an endpoint's SPA range to find
 a region

On 14.01.25 10:59:27, Jonathan Cameron wrote:
> On Tue, 7 Jan 2025 15:10:01 +0100
> Robert Richter <rrichter@....com> wrote:

> > +static int cxl_port_calc_hpa(struct cxl_port *port, struct cxl_decoder *cxld,
> > +			     struct range *hpa_range)
> > +{
> > +	struct range hpa = *hpa_range;
> > +	u64 len = range_len(&hpa);
> > +
> > +	if (!port->to_hpa)
> > +		return 0;
> > +
> > +	/* Translate HPA to the next upper domain. */
> > +	hpa.start = port->to_hpa(cxld, hpa.start);
> > +	hpa.end = port->to_hpa(cxld, hpa.end);
> > +
> > +	if (!hpa.start || !hpa.end ||
> 
> On general basis, why can't hpa.start be 0?
> It is an unusual physical memory map, but technically possible on some
> architectures.
> 
> > +	    hpa.start == ULLONG_MAX || hpa.end == ULLONG_MAX) {
> > +		dev_warn(&port->dev,
> > +			"CXL address translation: HPA range invalid: %#llx-%#llx:%#llx-%#llx(%s)\n",
> > +			hpa.start, hpa.end, hpa_range->start,
> > +			hpa_range->end, dev_name(&cxld->dev));
> > +		return -ENXIO;
> > +	}

> > @@ -3214,26 +3249,47 @@ cxl_port_find_switch_decoder(struct cxl_port *port, struct range *hpa)
> >  static int cxl_endpoint_initialize(struct cxl_endpoint_decoder *cxled)
> >  {
> >  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> > -	struct cxl_port *iter = cxled_to_port(cxled);
> > -	struct range *hpa = &cxled->cxld.hpa_range;
> > +	struct cxl_port *parent, *iter = cxled_to_port(cxled);
> 
> I'd prefer that spit into two lines. Mixing cases that allocate and ones
> that don't isn't great for readability.  Would also reduce the diff a little
> which is always nice!
> 
> > +	struct range hpa = cxled->cxld.hpa_range;
> >  	struct cxl_decoder *cxld = &cxled->cxld;
> >  

Changed both, thanks.

-Robert