linux-kernel - [RFC PATCH v1 2/2] cxl/cli: enforce HPA-descending teardown order for destroy-region

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Message-ID: <20251125143826.282312-3-pawel.mielimonka@fujitsu.com>
Date: Tue, 25 Nov 2025 23:38:24 +0900
From: Pawel Mielimonka <pawel.mielimonka@...itsu.com>
To: dan.j.williams@...el.com,
	alison.schofield@...el.com
Cc: Smita.KoralahalliChannabasappa@....com,
	linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	dave@...olabs.net,
	jonathan.cameron@...wei.com,
	dave.jiang@...el.com,
	vishal.l.verma@...el.com,
	ira.weiny@...el.com,
	Pawel Mielimonka <pawel.mielimonka@...itsu.com>
Subject: [RFC PATCH v1 2/2] cxl/cli: enforce HPA-descending teardown order for destroy-region

Implement destroy_multiple_regions() and bypass the generic
do_region_xable() path for ACTION_DESTROY. Regions are collected and
sorted by HPA, then destroyed from highest to lowest, stopping at the
first "matching after skipped" to provide user with better error log.
This prevents attempts on non-last regions and aligns destroy-region
with required decoder programming order.

Signed-off-by: Pawel Mielimonka <pawel.mielimonka@...itsu.com>
---
 cxl/region.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 3 deletions(-)

diff --git a/cxl/region.c b/cxl/region.c
index 58765b3d..1bf1901a 100644
--- a/cxl/region.c
+++ b/cxl/region.c
@@ -950,6 +950,57 @@ static int destroy_region(struct cxl_region *region)
 	return cxl_region_delete(region);
 }
 
+static int destroy_multiple_regions(struct parsed_params *p,
+				 struct cxl_decoder *decoder,
+				 int *count)
+{
+	struct cxl_region **list;
+	int nr, rc, i;
+	bool skipped = false;
+
+	rc = collect_regions_sorted(decoder, NULL, &list, &nr);
+	if (rc) {
+		log_err(&rl, "failed to allocate region list: %s\n", strerror(-rc));
+		return rc;
+	}
+
+	for (i = nr - 1; i >= 0; --i) {
+		struct cxl_region *region = NULL;
+
+		for (int j = 0; j < p->argc; j++) {
+			region = util_cxl_region_filter(list[i], p->argv[j]);
+			if (region)
+				break;
+		}
+
+		if (!region) {
+			skipped = true;
+			continue;
+		}
+
+		/* if current region matches filter, but previous didn't, destroying would
+		 * result in breaking HPA continuity
+		 */
+		if (skipped) {
+			log_err(&rl, "failed to destroy %s: not a valid HPA suffix under %s\n",
+				cxl_region_get_devname(region),
+				cxl_decoder_get_devname(decoder));
+			rc = -EINVAL;
+			break;
+		}
+
+		rc = destroy_region(region);
+		if (rc) {
+			log_err(&rl, "%s: failed: %s\n",
+				cxl_region_get_devname(region), strerror(-rc));
+			break;
+		}
+		++(*count);
+	}
+	free(list);
+	return rc;
+}
+
 static int do_region_xable(struct cxl_region *region, enum region_actions action)
 {
 	switch (action) {
@@ -957,8 +1008,6 @@ static int do_region_xable(struct cxl_region *region, enum region_actions action
 		return cxl_region_enable(region);
 	case ACTION_DISABLE:
 		return disable_region(region);
-	case ACTION_DESTROY:
-		return destroy_region(region);
 	default:
 		return -EINVAL;
 	}
@@ -1026,7 +1075,12 @@ static int region_action(int argc, const char **argv, struct cxl_ctx *ctx,
 			if (!util_cxl_decoder_filter(decoder,
 						     param.root_decoder))
 				continue;
-			rc = decoder_region_action(p, decoder, action, count);
+
+			if (action == ACTION_DESTROY)
+				rc = destroy_multiple_regions(p, decoder, count);
+			else
+				rc = decoder_region_action(p, decoder, action, count);
+
 			if (rc)
 				err_rc = rc;
 		}
-- 
2.45.1.windows.1