From ad5ca55f6bdb47c957b681c7358bb3719ba4ee82 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Tue, 23 Sep 2008 14:00:42 -0700 Subject: 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 Cc: Suresh Siddha Cc: arjan@linux.intel.com Cc: venkatesh.pallipadi@intel.com Cc: jeremy@goop.org Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-) (limited to 'arch/x86') 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 { int curpage; }; +/* + * 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. + */ +static DEFINE_SPINLOCK(cpa_lock); + #define CPA_FLUSHTLB 1 #define CPA_ARRAY 2 @@ -453,7 +461,13 @@ static int split_large_page(pte_t *kpte, unsigned long address) unsigned int i, level; pte_t *pbase, *tmp; pgprot_t ref_prot; - struct page *base = alloc_pages(GFP_KERNEL, 0); + struct page *base; + + if (!debug_pagealloc) + spin_unlock(&cpa_lock); + base = alloc_pages(GFP_KERNEL, 0); + if (!debug_pagealloc) + spin_lock(&cpa_lock); if (!base) return -ENOMEM; @@ -594,7 +608,25 @@ repeat: */ err = split_large_page(kpte, address); if (!err) { - cpa->flags |= CPA_FLUSHTLB; + /* + * 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, that 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." + * + * We do this global tlb flush inside the cpa_lock, so that we + * don't allow any other cpu, with stale tlb entries change the + * page attribute in parallel, that also falls into the + * just split large page entry. + */ + flush_tlb_all(); goto repeat; } @@ -686,7 +718,11 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias) if (cpa->flags & CPA_ARRAY) cpa->numpages = 1; + if (!debug_pagealloc) + spin_lock(&cpa_lock); ret = __change_page_attr(cpa, checkalias); + if (!debug_pagealloc) + spin_unlock(&cpa_lock); if (ret) return ret; -- cgit v1.2.3