Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c38116bb authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

x86/mm/cpa: Better use CLFLUSHOPT 



Currently we issue an MFENCE before and after flushing a range. This
means that if we flush a bunch of single page ranges -- like with the
cpa array, we issue a whole bunch of superfluous MFENCEs.

Reorgainze the code a little to avoid this.

[ mingo: capitalize instructions, tweak changelog and comments. ]

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom.StDenis@amd.com
Cc: dave.hansen@intel.com
Link: http://lkml.kernel.org/r/20181203171043.626999883@infradead.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent fe0937b2

arch/x86/mm/pageattr.c

+17 −12
Original line number Diff line number Diff line
@@ -251,15 +251,7 @@ static unsigned long __cpa_addr(struct cpa_data *cpa, unsigned long idx) 
 * Flushing functions

 */



/**

 * clflush_cache_range - flush a cache range with clflush

 * @vaddr:	virtual start address

 * @size:	number of bytes to flush

 *

 * clflushopt is an unordered instruction which needs fencing with mfence or

 * sfence to avoid ordering issues.

 */

void clflush_cache_range(void *vaddr, unsigned int size)

static void clflush_cache_range_opt(void *vaddr, unsigned int size)

{

	const unsigned long clflush_size = boot_cpu_data.x86_clflush_size;

	void *p = (void *)((unsigned long)vaddr & ~(clflush_size - 1));
@@ -268,11 +260,22 @@ void clflush_cache_range(void *vaddr, unsigned int size) 
	if (p >= vend)

		return;



	mb();



	for (; p < vend; p += clflush_size)

		clflushopt(p);

}



/**

 * clflush_cache_range - flush a cache range with clflush

 * @vaddr:	virtual start address

 * @size:	number of bytes to flush

 *

 * CLFLUSHOPT is an unordered instruction which needs fencing with MFENCE or

 * SFENCE to avoid ordering issues.

 */

void clflush_cache_range(void *vaddr, unsigned int size)

{

	mb();

	clflush_cache_range_opt(vaddr, size);

	mb();

}

EXPORT_SYMBOL_GPL(clflush_cache_range);
@@ -333,6 +336,7 @@ static void cpa_flush(struct cpa_data *data, int cache) 
	if (!cache)

		return;



	mb();

	for (i = 0; i < cpa->numpages; i++) {

		unsigned long addr = __cpa_addr(cpa, i);

		unsigned int level;
@@ -343,8 +347,9 @@ static void cpa_flush(struct cpa_data *data, int cache) 
		 * Only flush present addresses:

		 */

		if (pte && (pte_val(*pte) & _PAGE_PRESENT))

			clflush_cache_range((void *)addr, PAGE_SIZE);

			clflush_cache_range_opt((void *)addr, PAGE_SIZE);

	}

	mb();

}



static bool overlaps(unsigned long r1_start, unsigned long r1_end,