[PATCH 5/5] memremap: provide a not device managed memremap_pages

Christoph Hellwig
2019-08-11T08:15:37Z

The kvmppc ultravisor code wants a device private memory pool that is
system wide and not attached to a device. Instead of faking up one
provide a low-level memremap_pages for it. Note that this function is
not exported, and doesn't have a cleanup routine associated with it to
discourage use from more driver like users.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/memremap.h | 1 +
mm/memremap.c | 74 ++++++++++++++++++++++++----------------
2 files changed, 45 insertions(+), 30 deletions(-)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 8f0013e18e14..eac23e88a94a 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -123,6 +123,7 @@ static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
}

#ifdef CONFIG_ZONE_DEVICE
+void *memremap_pages(struct dev_pagemap *pgmap, int nid);
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
diff --git a/mm/memremap.c b/mm/memremap.c
index 09a087ca30ff..7b7575330db4 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -137,27 +137,12 @@ static void dev_pagemap_percpu_release(struct percpu_ref *ref)
complete(&pgmap->done);
}

-/**
- * devm_memremap_pages - remap and provide memmap backing for the given resource
- * @dev: hosting device for @res
- * @pgmap: pointer to a struct dev_pagemap
- *
- * Notes:
- * 1/ At a minimum the res and type members of @pgmap must be initialized
- * by the caller before passing it to this function
- *
- * 2/ The altmap field may optionally be initialized, in which case
- * PGMAP_ALTMAP_VALID must be set in pgmap->flags.
- *
- * 3/ The ref field may optionally be provided, in which pgmap->ref must be
- * 'live' on entry and will be killed and reaped at
- * devm_memremap_pages_release() time, or if this routine fails.
- *
- * 4/ res is expected to be a host memory range that could feasibly be
- * treated as a "System RAM" range, i.e. not a device mmio range, but
- * this is not enforced.
+/*
+ * This version is not intended for system resources only, and there is no
+ * way to clean up the resource acquisitions. If you need to clean up you
+ * probably want dev_memremap_pages below.
*/
-void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
+void *memremap_pages(struct dev_pagemap *pgmap, int nid)
{
struct resource *res = &pgmap->res;
struct dev_pagemap *conflict_pgmap;
@@ -168,7 +153,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
.altmap = pgmap_altmap(pgmap),
};
pgprot_t pgprot = PAGE_KERNEL;
- int error, nid, is_ram;
+ int error, is_ram;
bool need_devmap_managed = true;

switch (pgmap->type) {
@@ -223,7 +208,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)

conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL);
if (conflict_pgmap) {
- dev_WARN(dev, "Conflicting mapping in same section\n");
+ WARN(1, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
error = -ENOMEM;
goto err_array;
@@ -231,7 +216,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)

conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->end), NULL);
if (conflict_pgmap) {
- dev_WARN(dev, "Conflicting mapping in same section\n");
+ WARN(1, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
error = -ENOMEM;
goto err_array;
@@ -252,7 +237,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
if (error)
goto err_array;

- nid = dev_to_node(dev);
if (nid < 0)
nid = numa_mem_id();

@@ -308,12 +292,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
PHYS_PFN(res->start),
PHYS_PFN(resource_size(res)), pgmap);
percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
-
- error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
- pgmap);
- if (error)
- return ERR_PTR(error);
-
return __va(res->start);

err_add_memory:
@@ -328,6 +306,42 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
devmap_managed_enable_put();
return ERR_PTR(error);
}
+
+/**
+ * devm_memremap_pages - remap and provide memmap backing for the given resource
+ * @dev: hosting device for @res
+ * @pgmap: pointer to a struct dev_pagemap
+ *
+ * Notes:
+ * 1/ At a minimum the res and type members of @pgmap must be initialized
+ * by the caller before passing it to this function
+ *
+ * 2/ The altmap field may optionally be initialized, in which case
+ * PGMAP_ALTMAP_VALID must be set in pgmap->flags.
+ *
+ * 3/ The ref field may optionally be provided, in which pgmap->ref must be
+ * 'live' on entry and will be killed and reaped at
+ * devm_memremap_pages_release() time, or if this routine fails.
+ *
+ * 4/ res is expected to be a host memory range that could feasibly be
+ * treated as a "System RAM" range, i.e. not a device mmio range, but
+ * this is not enforced.
+ */
+void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
+{
+ int error;
+ void *ret;
+
+ ret = memremap_pages(pgmap, dev_to_node(dev));
+ if (IS_ERR(ret))
+ return ret;
+
+ error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
+ pgmap);
+ if (error)
+ return ERR_PTR(error);
+ return ret;
+}
EXPORT_SYMBOL_GPL(devm_memremap_pages);

void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
--
2.20.1