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Message-ID: <20250403183315.286710-2-terry.bowman@amd.com>
Date: Thu, 3 Apr 2025 13:33:12 -0500
From: Terry Bowman <terry.bowman@....com>
To: <dave@...olabs.net>, <jonathan.cameron@...wei.com>,
<dave.jiang@...el.com>, <alison.schofield@...el.com>,
<vishal.l.verma@...el.com>, <ira.weiny@...el.com>,
<dan.j.williams@...el.com>, <willy@...radead.org>, <jack@...e.cz>,
<rafael@...nel.org>, <len.brown@...el.com>, <pavel@....cz>,
<ming.li@...omail.com>, <nathan.fontenot@....com>,
<Smita.KoralahalliChannabasappa@....com>, <huang.ying.caritas@...il.com>,
<yaoxt.fnst@...itsu.com>, <peterz@...radead.org>,
<gregkh@...uxfoundation.org>, <quic_jjohnson@...cinc.com>,
<ilpo.jarvinen@...ux.intel.com>, <bhelgaas@...gle.com>,
<andriy.shevchenko@...ux.intel.com>, <mika.westerberg@...ux.intel.com>,
<akpm@...ux-foundation.org>, <gourry@...rry.net>,
<linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>,
<linux-pm@...r.kernel.org>, <rrichter@....com>, <benjamin.cheatham@....com>,
<PradeepVineshReddy.Kodamati@....com>, <lizhijian@...itsu.com>
Subject: [PATCH v3 1/4] kernel/resource: Provide mem region release for SOFT RESERVES
From: Nathan Fontenot <nathan.fontenot@....com>
Add a release_Sam_region_adjustable() interface to allow for
removing SOFT RESERVE memory resources. This extracts out the code
to remove a mem region into a common __release_mem_region_adjustable()
routine, this routine takes additional parameters of an IORES
descriptor type to add checks for IORES_DESC_* and a flag to check
for IORESOURCE_BUSY to control it's behavior.
The existing release_mem_region_adjustable() is a front end to the
common code and a new release_srmem_region_adjustable() is added to
release SOFT RESERVE resources.
Signed-off-by: Nathan Fontenot <nathan.fontenot@....com>
Signed-off-by: Terry Bowman <terry.bowman@....com>
---
include/linux/ioport.h | 3 +++
kernel/resource.c | 55 +++++++++++++++++++++++++++++++++++++++---
2 files changed, 54 insertions(+), 4 deletions(-)
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 5385349f0b8a..718360c9c724 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -357,6 +357,9 @@ extern void __release_region(struct resource *, resource_size_t,
#ifdef CONFIG_MEMORY_HOTREMOVE
extern void release_mem_region_adjustable(resource_size_t, resource_size_t);
#endif
+#ifdef CONFIG_CXL_REGION
+extern void release_srmem_region_adjustable(resource_size_t, resource_size_t);
+#endif
#ifdef CONFIG_MEMORY_HOTPLUG
extern void merge_system_ram_resource(struct resource *res);
#endif
diff --git a/kernel/resource.c b/kernel/resource.c
index 12004452d999..0195b31064b0 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1387,7 +1387,7 @@ void __release_region(struct resource *parent, resource_size_t start,
}
EXPORT_SYMBOL(__release_region);
-#ifdef CONFIG_MEMORY_HOTREMOVE
+#if defined(CONFIG_MEMORY_HOTREMOVE) || defined(CONFIG_CXL_REGION)
/**
* release_mem_region_adjustable - release a previously reserved memory region
* @start: resource start address
@@ -1407,7 +1407,10 @@ EXPORT_SYMBOL(__release_region);
* assumes that all children remain in the lower address entry for
* simplicity. Enhance this logic when necessary.
*/
-void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
+static void __release_mem_region_adjustable(resource_size_t start,
+ resource_size_t size,
+ bool busy_check,
+ int res_desc)
{
struct resource *parent = &iomem_resource;
struct resource *new_res = NULL;
@@ -1446,7 +1449,12 @@ void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
if (!(res->flags & IORESOURCE_MEM))
break;
- if (!(res->flags & IORESOURCE_BUSY)) {
+ if (busy_check && !(res->flags & IORESOURCE_BUSY)) {
+ p = &res->child;
+ continue;
+ }
+
+ if (res_desc != IORES_DESC_NONE && res->desc != res_desc) {
p = &res->child;
continue;
}
@@ -1496,7 +1504,46 @@ void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
write_unlock(&resource_lock);
free_resource(new_res);
}
-#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/**
+ * release_mem_region_adjustable - release a previously reserved memory region
+ * @start: resource start address
+ * @size: resource region size
+ *
+ * This interface is intended for memory hot-delete. The requested region
+ * is released from a currently busy memory resource. The requested region
+ * must either match exactly or fit into a single busy resource entry. In
+ * the latter case, the remaining resource is adjusted accordingly.
+ * Existing children of the busy memory resource must be immutable in the
+ * request.
+ *
+ * Note:
+ * - Additional release conditions, such as overlapping region, can be
+ * supported after they are confirmed as valid cases.
+ * - When a busy memory resource gets split into two entries, the code
+ * assumes that all children remain in the lower address entry for
+ * simplicity. Enhance this logic when necessary.
+ */
+void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
+{
+ return __release_mem_region_adjustable(start, size,
+ true, IORES_DESC_NONE);
+}
+EXPORT_SYMBOL(release_mem_region_adjustable);
+#endif
+
+#ifdef CONFIG_CXL_REGION
+void release_srmem_region_adjustable(resource_size_t start,
+ resource_size_t size)
+{
+ return __release_mem_region_adjustable(start, size,
+ false, IORES_DESC_SOFT_RESERVED);
+}
+EXPORT_SYMBOL(release_srmem_region_adjustable);
+#endif
+
#ifdef CONFIG_MEMORY_HOTPLUG
static bool system_ram_resources_mergeable(struct resource *r1,
--
2.34.1
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