Commit b8d7044b authored by Haozhong Zhang's avatar Haozhong Zhang Committed by Radim Krčmář
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x86/mm: add a function to check if a pfn is UC/UC-/WC 

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parent 05992edc

arch/x86/include/asm/pat.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -22,4 +22,6 @@ int io_reserve_memtype(resource_size_t start, resource_size_t end, 




void io_free_memtype(resource_size_t start, resource_size_t end);

void io_free_memtype(resource_size_t start, resource_size_t end);





bool pat_pfn_immune_to_uc_mtrr(unsigned long pfn);



#endif /* _ASM_X86_PAT_H */
 
#endif /* _ASM_X86_PAT_H */

arch/x86/mm/pat.c

+19 −0
Original line number Original line Diff line number Diff line
@@ -677,6 +677,25 @@ static enum page_cache_mode lookup_memtype(u64 paddr) 
	return rettype;

	return rettype;

}

}





/**

 * pat_pfn_immune_to_uc_mtrr - Check whether the PAT memory type

 * of @pfn cannot be overridden by UC MTRR memory type.

 *

 * Only to be called when PAT is enabled.

 *

 * Returns true, if the PAT memory type of @pfn is UC, UC-, or WC.

 * Returns false in other cases.

 */

bool pat_pfn_immune_to_uc_mtrr(unsigned long pfn)

{

	enum page_cache_mode cm = lookup_memtype(PFN_PHYS(pfn));



	return cm == _PAGE_CACHE_MODE_UC ||

	       cm == _PAGE_CACHE_MODE_UC_MINUS ||

	       cm == _PAGE_CACHE_MODE_WC;

}

EXPORT_SYMBOL_GPL(pat_pfn_immune_to_uc_mtrr);



/**

/**

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

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

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

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