linux-kernel - Re: [PATCH v9 13/13] cxl: Disable HPA/SPA translation handlers for Normalized Addressing

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Message-ID: <20260114182203.000061af@huawei.com>
Date: Wed, 14 Jan 2026 18:22:03 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
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>, 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>, Joshua Hahn <joshua.hahnjy@...il.com>
Subject: Re: [PATCH v9 13/13] cxl: Disable HPA/SPA translation handlers for
 Normalized Addressing

On Sat, 10 Jan 2026 12:46:58 +0100
Robert Richter <rrichter@....com> wrote:

> The root decoder provides the callbacks hpa_to_spa and spa_to_hpa to
> perform Host Physical Address (HPA) and System Physical Address
> translations, respectively. The callbacks are required to convert
> addresses when HPA != SPA. XOR interleaving depends on this mechanism,
> and the necessary handlers are implemented.
> 
> The translation handlers are used for poison injection
> (trace_cxl_poison, cxl_poison_inject_fops) and error handling
> (cxl_event_trace_record).
> 
> In AMD Zen5 systems with Normalized Addressing, endpoint addresses are
> not SPAs, and translation handlers are required for these features to
> function correctly.
> 
> Now, as ACPI PRM translation could be expensive in tracing or error
> handling code paths, do not yet enable translations to avoid its
> intensive use. Instead, disable those features which are used only for
> debugging and enhanced logging.
> 
> Introduce the flag CXL_REGION_F_NORM_ADDR that indicates Normalized
> Addressing for a region and use it to disable poison injection and DPA
> to HPA conversion.
> 
> Note: Dropped unused CXL_DECODER_F_MASK macro.

Meh, ideally that would be a precusor patch that Dave could pick up immediately.

Hopefully the whole thing merges though and so we don't have to care
about that.

Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>