linux-kernel - [PATCH 1/3] cxl: Simplify cxl_rd

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Message-ID: <20251112205105.1271726-2-rrichter@amd.com>
Date: Wed, 12 Nov 2025 21:51:02 +0100
From: Robert Richter <rrichter@....com>
To: 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>
CC: <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>, Robert Richter <rrichter@....com>
Subject: [PATCH 1/3] cxl: Simplify cxl_rd_ops allocation and handling

A root decoder's callback handlers are collected in struct cxl_rd_ops.
The structure is dynamically allocated, though it contains only a few
pointers in it. This also requires to check two pointes to check for
the existance of a callback.

Simplify the allocation, release and handler check by embedding the
ops statically in struct cxl_root_decoder.

Implementation is equivalent to how struct cxl_root_ops handles the
callbacks.

Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/acpi.c        |  8 ++------
 drivers/cxl/core/region.c | 20 +++++---------------
 drivers/cxl/cxl.h         |  2 +-
 3 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index d5119de7f5a9..fab736aa77dc 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -487,12 +487,8 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxlrd->qos_class = cfmws->qtg_id;
 
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR) {
-		cxlrd->ops = kzalloc(sizeof(*cxlrd->ops), GFP_KERNEL);
-		if (!cxlrd->ops)
-			return -ENOMEM;
-
-		cxlrd->ops->hpa_to_spa = cxl_apply_xor_maps;
-		cxlrd->ops->spa_to_hpa = cxl_apply_xor_maps;
+		cxlrd->ops.hpa_to_spa = cxl_apply_xor_maps;
+		cxlrd->ops.spa_to_hpa = cxl_apply_xor_maps;
 	}
 
 	rc = cxl_decoder_add(cxld);
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 451e5492911c..2b5ae5d9a4b6 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2958,16 +2958,6 @@ static bool cxl_is_hpa_in_chunk(u64 hpa, struct cxl_region *cxlr, int pos)
 	return false;
 }
 
-static bool has_hpa_to_spa(struct cxl_root_decoder *cxlrd)
-{
-	return cxlrd->ops && cxlrd->ops->hpa_to_spa;
-}
-
-static bool has_spa_to_hpa(struct cxl_root_decoder *cxlrd)
-{
-	return cxlrd->ops && cxlrd->ops->spa_to_hpa;
-}
-
 #define CXL_POS_ZERO 0
 /**
  * cxl_validate_translation_params
@@ -3141,8 +3131,8 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	hpa = hpa_offset + p->res->start + p->cache_size;
 
 	/* Root decoder translation overrides typical modulo decode */
-	if (has_hpa_to_spa(cxlrd))
-		hpa = cxlrd->ops->hpa_to_spa(cxlrd, hpa);
+	if (cxlrd->ops.hpa_to_spa)
+		hpa = cxlrd->ops.hpa_to_spa(cxlrd, hpa);
 
 	if (!cxl_resource_contains_addr(p->res, hpa)) {
 		dev_dbg(&cxlr->dev,
@@ -3151,7 +3141,7 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	}
 
 	/* Simple chunk check, by pos & gran, only applies to modulo decodes */
-	if (!has_hpa_to_spa(cxlrd) && (!cxl_is_hpa_in_chunk(hpa, cxlr, pos)))
+	if (!cxlrd->ops.hpa_to_spa && !cxl_is_hpa_in_chunk(hpa, cxlr, pos))
 		return ULLONG_MAX;
 
 	return hpa;
@@ -3184,8 +3174,8 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
 	 * If the root decoder has SPA to CXL HPA callback, use it. Otherwise
 	 * CXL HPA is assumed to equal SPA.
 	 */
-	if (has_spa_to_hpa(cxlrd)) {
-		hpa = cxlrd->ops->spa_to_hpa(cxlrd, p->res->start + offset);
+	if (cxlrd->ops.spa_to_hpa) {
+		hpa = cxlrd->ops.spa_to_hpa(cxlrd, p->res->start + offset);
 		hpa_offset = hpa - p->res->start;
 	} else {
 		hpa_offset = offset;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 0481679eb109..91ff47382111 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -451,7 +451,7 @@ struct cxl_root_decoder {
 	void *platform_data;
 	struct mutex range_lock;
 	int qos_class;
-	struct cxl_rd_ops *ops;
+	struct cxl_rd_ops ops;
 	struct cxl_switch_decoder cxlsd;
 };
 
-- 
2.47.3