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Message-ID: <20250930044757.214798-2-Smita.KoralahalliChannabasappa@amd.com>
Date: Tue, 30 Sep 2025 04:47:53 +0000
From: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
To: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>,
<linux-pm@...r.kernel.org>
CC: Davidlohr Bueso <dave@...olabs.net>, Jonathan Cameron
<jonathan.cameron@...wei.com>, Dave Jiang <dave.jiang@...el.com>, "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>, Matthew Wilcox <willy@...radead.org>, Jan Kara
<jack@...e.cz>, "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown
<len.brown@...el.com>, Pavel Machek <pavel@...nel.org>, Li Ming
<ming.li@...omail.com>, Jeff Johnson <jeff.johnson@....qualcomm.com>, "Ying
Huang" <huang.ying.caritas@...il.com>, Yao Xingtao <yaoxt.fnst@...itsu.com>,
Peter Zijlstra <peterz@...radead.org>, Greg KH <gregkh@...uxfoundation.org>,
Nathan Fontenot <nathan.fontenot@....com>, Smita Koralahalli
<Smita.KoralahalliChannabasappa@....com>, Terry Bowman
<terry.bowman@....com>, Robert Richter <rrichter@....com>, Benjamin Cheatham
<benjamin.cheatham@....com>, Zhijian Li <lizhijian@...itsu.com>, "Borislav
Petkov" <bp@...en8.de>, Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH v3 1/5] dax/hmem, e820, resource: Defer Soft Reserved registration until hmem is ready
From: Dan Williams <dan.j.williams@...el.com>
Insert Soft Reserved memory into a dedicated soft_reserve_resource tree
instead of the iomem_resource tree at boot.
Publishing Soft Reserved ranges into iomem too early causes conflicts with
CXL hotplug and region assembly failure, especially when Soft Reserved
overlaps CXL regions.
Re-inserting these ranges into iomem will be handled in follow-up patches,
after ensuring CXL window publication ordering is stabilized and when the
dax_hmem is ready to consume them.
This avoids trimming or deleting resources later and provides a cleaner
handoff between EFI-defined memory and CXL resource management.
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Co-developed-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
---
arch/x86/kernel/e820.c | 2 +-
drivers/cxl/acpi.c | 2 +-
drivers/dax/hmem/device.c | 4 +-
drivers/dax/hmem/hmem.c | 7 ++-
include/linux/ioport.h | 13 +++++-
kernel/resource.c | 92 +++++++++++++++++++++++++++++++++------
6 files changed, 100 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index c3acbd26408b..c32f144f0e4a 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -1153,7 +1153,7 @@ void __init e820__reserve_resources_late(void)
res = e820_res;
for (i = 0; i < e820_table->nr_entries; i++) {
if (!res->parent && res->end)
- insert_resource_expand_to_fit(&iomem_resource, res);
+ insert_resource_expand_to_fit(res);
res++;
}
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 712624cba2b6..3b73adf80bb4 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -839,7 +839,7 @@ static int add_cxl_resources(struct resource *cxl_res)
*/
cxl_set_public_resource(res, new);
- insert_resource_expand_to_fit(&iomem_resource, new);
+ __insert_resource_expand_to_fit(&iomem_resource, new);
next = res->sibling;
while (next && resource_overlaps(new, next)) {
diff --git a/drivers/dax/hmem/device.c b/drivers/dax/hmem/device.c
index f9e1a76a04a9..22732b729017 100644
--- a/drivers/dax/hmem/device.c
+++ b/drivers/dax/hmem/device.c
@@ -83,8 +83,8 @@ static __init int hmem_register_one(struct resource *res, void *data)
static __init int hmem_init(void)
{
- walk_iomem_res_desc(IORES_DESC_SOFT_RESERVED,
- IORESOURCE_MEM, 0, -1, NULL, hmem_register_one);
+ walk_soft_reserve_res_desc(IORES_DESC_SOFT_RESERVED, IORESOURCE_MEM, 0,
+ -1, NULL, hmem_register_one);
return 0;
}
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index c18451a37e4f..48f4642f4bb8 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -73,11 +73,14 @@ static int hmem_register_device(struct device *host, int target_nid,
return 0;
}
- rc = region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
- IORES_DESC_SOFT_RESERVED);
+ rc = region_intersects_soft_reserve(res->start, resource_size(res),
+ IORESOURCE_MEM,
+ IORES_DESC_SOFT_RESERVED);
if (rc != REGION_INTERSECTS)
return 0;
+ /* TODO: Add Soft-Reserved memory back to iomem */
+
id = memregion_alloc(GFP_KERNEL);
if (id < 0) {
dev_err(host, "memregion allocation failure for %pr\n", res);
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index e8b2d6aa4013..e20226870a81 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -232,6 +232,9 @@ struct resource_constraint {
/* PC/ISA/whatever - the normal PC address spaces: IO and memory */
extern struct resource ioport_resource;
extern struct resource iomem_resource;
+#ifdef CONFIG_EFI_SOFT_RESERVE
+extern struct resource soft_reserve_resource;
+#endif
extern struct resource *request_resource_conflict(struct resource *root, struct resource *new);
extern int request_resource(struct resource *root, struct resource *new);
@@ -242,7 +245,8 @@ extern void reserve_region_with_split(struct resource *root,
const char *name);
extern struct resource *insert_resource_conflict(struct resource *parent, struct resource *new);
extern int insert_resource(struct resource *parent, struct resource *new);
-extern void insert_resource_expand_to_fit(struct resource *root, struct resource *new);
+extern void __insert_resource_expand_to_fit(struct resource *root, struct resource *new);
+extern void insert_resource_expand_to_fit(struct resource *new);
extern int remove_resource(struct resource *old);
extern void arch_remove_reservations(struct resource *avail);
extern int allocate_resource(struct resource *root, struct resource *new,
@@ -409,6 +413,13 @@ walk_system_ram_res_rev(u64 start, u64 end, void *arg,
extern int
walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start, u64 end,
void *arg, int (*func)(struct resource *, void *));
+extern int
+walk_soft_reserve_res_desc(unsigned long desc, unsigned long flags,
+ u64 start, u64 end, void *arg,
+ int (*func)(struct resource *, void *));
+extern int
+region_intersects_soft_reserve(resource_size_t start, size_t size,
+ unsigned long flags, unsigned long desc);
struct resource *devm_request_free_mem_region(struct device *dev,
struct resource *base, unsigned long size);
diff --git a/kernel/resource.c b/kernel/resource.c
index f9bb5481501a..70e750cc0d7b 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -321,13 +321,14 @@ static bool is_type_match(struct resource *p, unsigned long flags, unsigned long
}
/**
- * find_next_iomem_res - Finds the lowest iomem resource that covers part of
- * [@start..@end].
+ * find_next_res - Finds the lowest resource that covers part of
+ * [@start..@end].
*
* If a resource is found, returns 0 and @*res is overwritten with the part
* of the resource that's within [@start..@end]; if none is found, returns
* -ENODEV. Returns -EINVAL for invalid parameters.
*
+ * @parent: resource tree root to search
* @start: start address of the resource searched for
* @end: end address of same resource
* @flags: flags which the resource must have
@@ -337,9 +338,9 @@ static bool is_type_match(struct resource *p, unsigned long flags, unsigned long
* The caller must specify @start, @end, @flags, and @desc
* (which may be IORES_DESC_NONE).
*/
-static int find_next_iomem_res(resource_size_t start, resource_size_t end,
- unsigned long flags, unsigned long desc,
- struct resource *res)
+static int find_next_res(struct resource *parent, resource_size_t start,
+ resource_size_t end, unsigned long flags,
+ unsigned long desc, struct resource *res)
{
struct resource *p;
@@ -351,7 +352,7 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
read_lock(&resource_lock);
- for_each_resource(&iomem_resource, p, false) {
+ for_each_resource(parent, p, false) {
/* If we passed the resource we are looking for, stop */
if (p->start > end) {
p = NULL;
@@ -382,16 +383,23 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
return p ? 0 : -ENODEV;
}
-static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
- unsigned long flags, unsigned long desc,
- void *arg,
- int (*func)(struct resource *, void *))
+static int find_next_iomem_res(resource_size_t start, resource_size_t end,
+ unsigned long flags, unsigned long desc,
+ struct resource *res)
+{
+ return find_next_res(&iomem_resource, start, end, flags, desc, res);
+}
+
+static int walk_res_desc(struct resource *parent, resource_size_t start,
+ resource_size_t end, unsigned long flags,
+ unsigned long desc, void *arg,
+ int (*func)(struct resource *, void *))
{
struct resource res;
int ret = -EINVAL;
while (start < end &&
- !find_next_iomem_res(start, end, flags, desc, &res)) {
+ !find_next_res(parent, start, end, flags, desc, &res)) {
ret = (*func)(&res, arg);
if (ret)
break;
@@ -402,6 +410,15 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
return ret;
}
+static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
+ unsigned long flags, unsigned long desc,
+ void *arg,
+ int (*func)(struct resource *, void *))
+{
+ return walk_res_desc(&iomem_resource, start, end, flags, desc, arg, func);
+}
+
+
/**
* walk_iomem_res_desc - Walks through iomem resources and calls func()
* with matching resource ranges.
@@ -426,6 +443,26 @@ int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,
}
EXPORT_SYMBOL_GPL(walk_iomem_res_desc);
+#ifdef CONFIG_EFI_SOFT_RESERVE
+struct resource soft_reserve_resource = {
+ .name = "Soft Reserved",
+ .start = 0,
+ .end = -1,
+ .desc = IORES_DESC_SOFT_RESERVED,
+ .flags = IORESOURCE_MEM,
+};
+EXPORT_SYMBOL_GPL(soft_reserve_resource);
+
+int walk_soft_reserve_res_desc(unsigned long desc, unsigned long flags,
+ u64 start, u64 end, void *arg,
+ int (*func)(struct resource *, void *))
+{
+ return walk_res_desc(&soft_reserve_resource, start, end, flags, desc,
+ arg, func);
+}
+EXPORT_SYMBOL_GPL(walk_soft_reserve_res_desc);
+#endif
+
/*
* This function calls the @func callback against all memory ranges of type
* System RAM which are marked as IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY.
@@ -648,6 +685,22 @@ int region_intersects(resource_size_t start, size_t size, unsigned long flags,
}
EXPORT_SYMBOL_GPL(region_intersects);
+#ifdef CONFIG_EFI_SOFT_RESERVE
+int region_intersects_soft_reserve(resource_size_t start, size_t size,
+ unsigned long flags, unsigned long desc)
+{
+ int ret;
+
+ read_lock(&resource_lock);
+ ret = __region_intersects(&soft_reserve_resource, start, size, flags,
+ desc);
+ read_unlock(&resource_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(region_intersects_soft_reserve);
+#endif
+
void __weak arch_remove_reservations(struct resource *avail)
{
}
@@ -966,7 +1019,7 @@ EXPORT_SYMBOL_GPL(insert_resource);
* Insert a resource into the resource tree, possibly expanding it in order
* to make it encompass any conflicting resources.
*/
-void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
+void __insert_resource_expand_to_fit(struct resource *root, struct resource *new)
{
if (new->parent)
return;
@@ -997,7 +1050,20 @@ void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
* to use this interface. The former are built-in and only the latter,
* CXL, is a module.
*/
-EXPORT_SYMBOL_NS_GPL(insert_resource_expand_to_fit, "CXL");
+EXPORT_SYMBOL_NS_GPL(__insert_resource_expand_to_fit, "CXL");
+
+void insert_resource_expand_to_fit(struct resource *new)
+{
+ struct resource *root = &iomem_resource;
+
+#ifdef CONFIG_EFI_SOFT_RESERVE
+ if (new->desc == IORES_DESC_SOFT_RESERVED)
+ root = &soft_reserve_resource;
+#endif
+
+ __insert_resource_expand_to_fit(root, new);
+}
+EXPORT_SYMBOL_GPL(insert_resource_expand_to_fit);
/**
* remove_resource - Remove a resource in the resource tree
--
2.17.1
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