linux-kernel - [RFC] cxl/region: set numa node for target memdevs when a region is committed

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Message-ID: <20250314164629.6937-1-nifan.cxl@gmail.com>
Date: Fri, 14 Mar 2025 09:40:19 -0700
From: nifan.cxl@...il.com
To: dave.jiang@...el.com,
	alison.schofield@...el.com,
	vishal.l.verma@...el.com,
	ira.weiny@...el.com,
	dan.j.williams@...el.com,
	Jonathan.Cameron@...wei.com
Cc: linux-cxl@...r.kernel.org,
	a.manzanares@...sung.com,
	dave@...olabs.net,
	linux-kernel@...r.kernel.org,
	nifan.cxl@...il.com,
	anisa.su887@...il.com,
	Fan Ni <fan.ni@...sung.com>
Subject: [RFC] cxl/region: set numa node for target memdevs when a region is committed

From: Fan Ni <fan.ni@...sung.com>

There is a sysfs attribute named "numa_node" for cxl memory device.
however, it is never set so -1 is returned whenever it is read.

With this change, the numa_node of each target memdev is set based on the
start address of the hpa_range of the endpoint decoder it associated when a
cxl region is created; and it is reset when the region decoders are
reset.

Open qeustion: do we need to set the numa_node when the memdev is
probed instead of waiting until a region is created?

Signed-off-by: Fan Ni <fan.ni@...sung.com>
---
 drivers/cxl/core/region.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index e8d11a988fd9..935ee0b1dd26 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -242,6 +242,13 @@ static int cxl_region_invalidate_memregion(struct cxl_region *cxlr)
 	return 0;
 }
 
+static void cxl_mem_reset_numa_node(struct cxl_endpoint_decoder *cxled)
+{
+	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+
+	cxlmd->dev.numa_node = NUMA_NO_NODE;
+}
+
 static void cxl_region_decode_reset(struct cxl_region *cxlr, int count)
 {
 	struct cxl_region_params *p = &cxlr->params;
@@ -264,6 +271,7 @@ static void cxl_region_decode_reset(struct cxl_region *cxlr, int count)
 		if (cxlds->rcd)
 			goto endpoint_reset;
 
+		cxl_mem_reset_numa_node(cxled);
 		while (!is_cxl_root(to_cxl_port(iter->dev.parent)))
 			iter = to_cxl_port(iter->dev.parent);
 
@@ -304,6 +312,15 @@ static int commit_decoder(struct cxl_decoder *cxld)
 	return 0;
 }
 
+static void cxl_mem_set_numa_node(struct cxl_endpoint_decoder *cxled)
+{
+	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+	u64 addr = cxled->cxld.hpa_range.start;
+
+	cxlmd->dev.numa_node = phys_to_target_node(addr);
+	dev_dbg(&cxlmd->dev, "set numa node: %d\n", phys_to_target_node(addr));
+}
+
 static int cxl_region_decode_commit(struct cxl_region *cxlr)
 {
 	struct cxl_region_params *p = &cxlr->params;
@@ -340,6 +357,7 @@ static int cxl_region_decode_commit(struct cxl_region *cxlr)
 			cxled->cxld.reset(&cxled->cxld);
 			goto err;
 		}
+		cxl_mem_set_numa_node(cxled);
 	}
 
 	return 0;
-- 
2.47.2