| From | ira.weiny@intel ... | Subject | [PATCH V9 37/45] memremap_pages: Introduce devmap_protected() | Date | Thu, 10 Mar 2022 09:20:11 -0800 |
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From: Ira Weiny <ira.weiny@intel.com>
Consumers of protected dev_pagemaps can check the PGMAP_PROTECTION flag to see if the devmap is protected. However, most contexts will have a struct page not the pagemap structure directly.
Define devmap_protected() to determine if a page is part of a dev_pagemap mapping and if the page is protected by additional protections.
Signed-off-by: Ira Weiny <ira.weiny@intel.com> --- include/linux/mm.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 9ab799403004..4ca24329848a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1151,6 +1151,23 @@ static inline bool pgmap_protection_available(void) return pks_available(); } +DECLARE_STATIC_KEY_FALSE(dev_pgmap_protection_static_key); + +/* + * devmap_protected() requires a reference on the page to ensure there is no + * races with dev_pagemap tear down. + */ +static inline bool devmap_protected(struct page *page) +{ + if (!static_branch_unlikely(&dev_pgmap_protection_static_key)) + return false; + if (!is_zone_device_page(page)) + return false; + if (page->pgmap->flags & PGMAP_PROTECTION) + return true; + return false; +} + #else static inline bool pgmap_protection_available(void) -- 2.35.1
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