linux-kernel - Re: [PATCH v2 11/15] cxl/region: Use the endpoint's SPA range to check a region

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Message-ID: <Z7eHeuikvako1Xhh@gourry-fedora-PF4VCD3F>
Date: Thu, 20 Feb 2025 14:50:18 -0500
From: Gregory Price <gourry@...rry.net>
To: Robert Richter <rrichter@....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>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Davidlohr Bueso <dave@...olabs.net>, linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>,
	Terry Bowman <terry.bowman@....com>
Subject: Re: [PATCH v2 11/15] cxl/region: Use the endpoint's SPA range to
 check a region

On Tue, Feb 18, 2025 at 02:23:52PM +0100, Robert Richter wrote:
> Endpoints or switches requiring address translation might not be aware
> of the system's interleaving configuration. Then, the configured
> endpoint's address range might not match the expected range. In
> contrast, the SPA range of an endpoint is calculated applying platform
> specific address translation. That range is correct and can be used to
> check a region range.
> 
> Adjust the region range check and use the endpoint's SPA range to
> check it.
> 
> Signed-off-by: Robert Richter <rrichter@....com>

Explanation could be a little clearer, something like:

Endpoint and switch decoders may have an HPA range that differs from
the memory region's SPA range.  Utilize the device's calculated
spa_range instead of its hpa_range to validate the region mapping.


The interleave comments don't seem particularly relevant here unless i'm
missing something.

The content of the patch looks good.

Reviewed-by: Gregory Price <gourry@...rry.net>

> ---
>  drivers/cxl/core/region.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 3afcc9ca06ae..2ca24565757a 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1531,22 +1531,26 @@ static int cxl_port_setup_targets(struct cxl_port *port,
>  	if (test_bit(CXL_REGION_F_AUTO, &cxlr->flags)) {
>  		if (cxld->interleave_ways != iw ||
>  		    cxld->interleave_granularity != ig ||
> -		    cxld->hpa_range.start != p->res->start ||
> -		    cxld->hpa_range.end != p->res->end ||
> +		    cxled->spa_range.start != p->res->start ||
> +		    cxled->spa_range.end != p->res->end ||
>  		    ((cxld->flags & CXL_DECODER_F_ENABLE) == 0)) {
>  			dev_err(&cxlr->dev,
>  				"%s:%s %s expected iw: %d ig: %d %pr\n",
>  				dev_name(port->uport_dev), dev_name(&port->dev),
>  				__func__, iw, ig, p->res);
>  			dev_err(&cxlr->dev,
> -				"%s:%s %s got iw: %d ig: %d state: %s %#llx:%#llx\n",
> +				"%s:%s %s got iw: %d ig: %d state: %s %#llx-%#llx:%#llx-%#llx(%s):%#llx-%#llx(%s)\n",
>  				dev_name(port->uport_dev), dev_name(&port->dev),
>  				__func__, cxld->interleave_ways,
>  				cxld->interleave_granularity,
>  				(cxld->flags & CXL_DECODER_F_ENABLE) ?
>  					"enabled" :
>  					"disabled",
> -				cxld->hpa_range.start, cxld->hpa_range.end);
> +				p->res->start, p->res->end,
> +				cxled->spa_range.start, cxled->spa_range.end,
> +				dev_name(&cxled->cxld.dev),
> +				cxld->hpa_range.start, cxld->hpa_range.end,
> +				dev_name(&cxld->dev));
>  			return -ENXIO;
>  		}
>  	} else {
> -- 
> 2.39.5
>