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Commit f4ae5da0 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

x86: cpa, check if we changed anything and tlb flushing is necessary 



Flush tlbs only when there was a real change.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 72e458df

arch/x86/mm/pageattr.c

+17 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ struct cpa_data { 
	int		numpages;

	pgprot_t	mask_set;

	pgprot_t	mask_clr;

	int		flushtlb;

};



static inline int
@@ -329,11 +330,19 @@ static int __change_page_attr(unsigned long address, struct cpa_data *cpa) 
		 * not the memory it points to

		 */

		new_pte = pfn_pte(pte_pfn(old_pte), canon_pgprot(new_prot));



		/*

		 * Do we really change anything ?

		 */

		if (pte_val(old_pte) != pte_val(new_pte)) {

			set_pte_atomic(kpte, new_pte);

			cpa->flushtlb = 1;

		}

	} else {

		err = split_large_page(kpte, address);

		if (!err)

			goto repeat;

		cpa->flushtlb = 1;

	}

	return err;

}
@@ -438,9 +447,16 @@ static int change_page_attr_set_clr(unsigned long addr, int numpages, 
	cpa.numpages = numpages;

	cpa.mask_set = mask_set;

	cpa.mask_clr = mask_clr;

	cpa.flushtlb = 0;



	ret = __change_page_attr_set_clr(&cpa);



	/*

	 * Check whether we really changed something:

	 */

	if (!cpa.flushtlb)

		return ret;



	/*

	 * No need to flush, when we did not set any of the caching

	 * attributes: