Commit d414b83d authored by Mostafa Saleh's avatar Mostafa Saleh Committed by Joerg Roedel
Browse files

mm/page_ext: Add page_ext_get_from_phys() 



The IOMMU code operates on physical addresses which can be outside
of system RAM.

Add a new function page_ext_get_from_phys() to abstract the logic of
checking the address and returning the page_ext.

Signed-off-by: default avatarMostafa Saleh <smostafa@google.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent 2e2f6b0e

include/linux/page_ext.h

+6 −0
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ static inline bool page_ext_iter_next_fast_possible(unsigned long next_pfn) 
#endif



extern struct page_ext *page_ext_get(const struct page *page);

extern struct page_ext *page_ext_from_phys(phys_addr_t phys);

extern void page_ext_put(struct page_ext *page_ext);

extern struct page_ext *page_ext_lookup(unsigned long pfn);
@@ -215,6 +216,11 @@ static inline struct page_ext *page_ext_get(const struct page *page) 
	return NULL;

}



static inline struct page_ext *page_ext_from_phys(phys_addr_t phys)

{

	return NULL;

}



static inline void page_ext_put(struct page_ext *page_ext)

{

}

mm/page_ext.c

+23 −0
Original line number Diff line number Diff line
@@ -538,6 +538,29 @@ struct page_ext *page_ext_get(const struct page *page) 
	return page_ext;

}



/**

 * page_ext_from_phys() - Get the page_ext structure for a physical address.

 * @phys: The physical address to query.

 *

 * This function safely gets the `struct page_ext` associated with a given

 * physical address. It performs validation to ensure the address corresponds

 * to a valid, online struct page before attempting to access it.

 * It returns NULL for MMIO, ZONE_DEVICE, holes and offline memory.

 *

 * Return: NULL if no page_ext exists for this physical address.

 * Context: Any context.  Caller may not sleep until they have called

 * page_ext_put().

 */

struct page_ext *page_ext_from_phys(phys_addr_t phys)

{

	struct page *page = pfn_to_online_page(__phys_to_pfn(phys));



	if (!page)

		return NULL;



	return page_ext_get(page);

}



/**

 * page_ext_put() - Working with page extended information is done.

 * @page_ext: Page extended information received from page_ext_get().