These calls allows creation of system pages at a specific physical
address, which is useful for creating dummy backing pages which
correspond to unaddressable external memory at specific locations.
__add_memory_pages() adds the requested page range to /proc/iomem and
verifies that there are no overlaps. Once this succeeds, then the page
section is initialized, which may overlap with a prior request, since
section sizes are large, so ignore the latter overlap.
Signed-off-by: Jonathan Lemon <jonathan.le...@gmail.com>
---
include/linux/memory_hotplug.h | 4 +++
mm/memory_hotplug.c | 65 ++++++++++++++++++++++++++++++++--
2 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 375515803cd8..05e012e1a203 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -138,6 +138,10 @@ extern void __remove_pages(unsigned long start_pfn,
unsigned long nr_pages,
extern int __add_pages(int nid, unsigned long start_pfn, unsigned long
nr_pages,
struct mhp_params *params);
+struct resource *add_memory_pages(int nid, u64 start, u64 size,
+ struct mhp_params *params);
+void release_memory_pages(struct resource *res);
+
#ifndef CONFIG_ARCH_HAS_ADD_PAGES
static inline int add_pages(int nid, unsigned long start_pfn,
unsigned long nr_pages, struct mhp_params *params)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index da374cd3d45b..c1a923189869 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -125,8 +125,8 @@ static struct resource *register_memory_resource(u64 start,
u64 size,
resource_name, flags);
if (!res) {
- pr_debug("Unable to reserve System RAM region:
%016llx->%016llx\n",
- start, start + size);
+ pr_debug("Unable to reserve %s region: %016llx->%016llx\n",
+ resource_name, start, start + size);
return ERR_PTR(-EEXIST);
}
return res;
@@ -1118,6 +1118,67 @@ int add_memory(int nid, u64 start, u64 size)
}
EXPORT_SYMBOL_GPL(add_memory);
+static int __ref add_memory_section(int nid, struct resource *res,
+ struct mhp_params *params)
+{
+ u64 start, end, section_size;
+ int ret;
+
+ /* must align start/end with memory block size */
+ end = res->start + resource_size(res);
+ section_size = memory_block_size_bytes();
+ start = round_down(res->start, section_size);
+ end = round_up(end, section_size);
+
+ mem_hotplug_begin();
+ ret = __add_pages(nid,
+ PHYS_PFN(start), PHYS_PFN(end - start), params);
+ mem_hotplug_done();
+
+ return ret;
+}
+
+/* requires device_hotplug_lock, see add_memory_resource() */
+static struct resource * __ref __add_memory_pages(int nid, u64 start, u64 size,
+ struct mhp_params *params)
+{
+ struct resource *res;
+ int ret;
+
+ res = register_memory_resource(start, size, "Private RAM");
+ if (IS_ERR(res))
+ return res;
+
+ ret = add_memory_section(nid, res, params);
+ if (ret < 0 && ret != -EEXIST) {
+ release_memory_resource(res);
+ return ERR_PTR(ret);
+ }
+
+ return res;
+}
+
+struct resource *add_memory_pages(int nid, u64 start, u64 size,
+ struct mhp_params *params)
+{
+ struct resource *res;
+
+ lock_device_hotplug();
+ res = __add_memory_pages(nid, start, size, params);
+ unlock_device_hotplug();
+
+ return res;
+}
+EXPORT_SYMBOL_GPL(add_memory_pages);
+
+void release_memory_pages(struct resource *res)
+{
+ lock_device_hotplug();
+ release_memory_resource(res);
+ unlock_device_hotplug();
+}
+EXPORT_SYMBOL_GPL(release_memory_pages);
+
/*
* Add special, driver-managed memory to the system as system RAM. Such
* memory is not exposed via the raw firmware-provided memmap as system
--
2.24.1
