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authorSuresh Siddha <suresh.b.siddha@intel.com>2008-09-23 17:00:42 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-10 13:29:17 -0400
commitad5ca55f6bdb47c957b681c7358bb3719ba4ee82 (patch)
tree20ab9e06e840c939da21f6cd352cc5700c9bc9da /arch/x86/mm/pageattr.c
parent8311eb84bf842d345f543f4c62ca2b6ea26f638c (diff)
x86, cpa: srlz cpa(), global flush tlb after splitting big page and before doing cpa
Do a global flush tlb after splitting the large page and before we do the actual change page attribute in the PTE. With out this, we violate the TLB application note, which says "The TLBs may contain both ordinary and large-page translations for a 4-KByte range of linear addresses. This may occur if software modifies the paging structures so that the page size used for the address range changes. If the two translations differ with respect to page frame or attributes (e.g., permissions), processor behavior is undefined and may be implementation-specific." And also serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings) using cpa_lock. So that we don't allow any other cpu, with stale large tlb entries change the page attribute in parallel to some other cpu splitting a large page entry along with changing the attribute. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: arjan@linux.intel.com Cc: venkatesh.pallipadi@intel.com Cc: jeremy@goop.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/pageattr.c')
-rw-r--r--arch/x86/mm/pageattr.c40
1 files changed, 38 insertions, 2 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index f5e8663c0f75..b6374d653d06 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -35,6 +35,14 @@ struct cpa_data {
35 int curpage; 35 int curpage;
36}; 36};
37 37
38/*
39 * Serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings)
40 * using cpa_lock. So that we don't allow any other cpu, with stale large tlb
41 * entries change the page attribute in parallel to some other cpu
42 * splitting a large page entry along with changing the attribute.
43 */
44static DEFINE_SPINLOCK(cpa_lock);
45
38#define CPA_FLUSHTLB 1 46#define CPA_FLUSHTLB 1
39#define CPA_ARRAY 2 47#define CPA_ARRAY 2
40 48
@@ -453,7 +461,13 @@ static int split_large_page(pte_t *kpte, unsigned long address)
453 unsigned int i, level; 461 unsigned int i, level;
454 pte_t *pbase, *tmp; 462 pte_t *pbase, *tmp;
455 pgprot_t ref_prot; 463 pgprot_t ref_prot;
456 struct page *base = alloc_pages(GFP_KERNEL, 0); 464 struct page *base;
465
466 if (!debug_pagealloc)
467 spin_unlock(&cpa_lock);
468 base = alloc_pages(GFP_KERNEL, 0);
469 if (!debug_pagealloc)
470 spin_lock(&cpa_lock);
457 if (!base) 471 if (!base)
458 return -ENOMEM; 472 return -ENOMEM;
459 473
@@ -594,7 +608,25 @@ repeat:
594 */ 608 */
595 err = split_large_page(kpte, address); 609 err = split_large_page(kpte, address);
596 if (!err) { 610 if (!err) {
597 cpa->flags |= CPA_FLUSHTLB; 611 /*
612 * Do a global flush tlb after splitting the large page
613 * and before we do the actual change page attribute in the PTE.
614 *
615 * With out this, we violate the TLB application note, that says
616 * "The TLBs may contain both ordinary and large-page
617 * translations for a 4-KByte range of linear addresses. This
618 * may occur if software modifies the paging structures so that
619 * the page size used for the address range changes. If the two
620 * translations differ with respect to page frame or attributes
621 * (e.g., permissions), processor behavior is undefined and may
622 * be implementation-specific."
623 *
624 * We do this global tlb flush inside the cpa_lock, so that we
625 * don't allow any other cpu, with stale tlb entries change the
626 * page attribute in parallel, that also falls into the
627 * just split large page entry.
628 */
629 flush_tlb_all();
598 goto repeat; 630 goto repeat;
599 } 631 }
600 632
@@ -686,7 +718,11 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)
686 if (cpa->flags & CPA_ARRAY) 718 if (cpa->flags & CPA_ARRAY)
687 cpa->numpages = 1; 719 cpa->numpages = 1;
688 720
721 if (!debug_pagealloc)
722 spin_lock(&cpa_lock);
689 ret = __change_page_attr(cpa, checkalias); 723 ret = __change_page_attr(cpa, checkalias);
724 if (!debug_pagealloc)
725 spin_unlock(&cpa_lock);
690 if (ret) 726 if (ret)
691 return ret; 727 return ret;
692 728