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Commit 637b86e7 authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by H. Peter Anvin
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x86, pat: Add lookup_memtype to get the current memtype of a paddr 



Add a new routine lookup_memtype() to get the current memtype based on
the PAT reserves and frees.

Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent f5841740

arch/x86/mm/pat.c

+45 −0
Original line number Diff line number Diff line
@@ -573,6 +573,51 @@ int free_memtype(u64 start, u64 end) 
}





/**

 * lookup_memtype - Looksup the memory type for a physical address

 * @paddr: physical address of which memory type needs to be looked up

 *

 * Only to be called when PAT is enabled

 *

 * Returns _PAGE_CACHE_WB, _PAGE_CACHE_WC, _PAGE_CACHE_UC_MINUS or

 * _PAGE_CACHE_UC

 */

static unsigned long lookup_memtype(u64 paddr)

{

	int rettype = _PAGE_CACHE_WB;

	struct memtype *entry;



	if (is_ISA_range(paddr, paddr + PAGE_SIZE - 1))

		return rettype;



	if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) {

		struct page *page;

		spin_lock(&memtype_lock);

		page = pfn_to_page(paddr >> PAGE_SHIFT);

		rettype = get_page_memtype(page);

		spin_unlock(&memtype_lock);

		/*

		 * -1 from get_page_memtype() implies RAM page is in its

		 * default state and not reserved, and hence of type WB

		 */

		if (rettype == -1)

			rettype = _PAGE_CACHE_WB;



		return rettype;

	}



	spin_lock(&memtype_lock);



	entry = memtype_rb_search(&memtype_rbroot, paddr);

	if (entry != NULL)

		rettype = entry->type;

	else

		rettype = _PAGE_CACHE_UC_MINUS;



	spin_unlock(&memtype_lock);

	return rettype;

}



/**

 * io_reserve_memtype - Request a memory type mapping for a region of memory

 * @start: start (physical address) of the region