From d551aaa2f7e1387fa66093ce9914c2e91f283a50 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Thu, 17 Sep 2015 12:24:23 -0600 Subject: [PATCH] x86/mm: Fix __split_large_page() to handle large PAT bit __split_large_page() is called from __change_page_attr() to change the mapping attribute by splitting a given large page into smaller pages. This function uses pte_pfn() and pte_pgprot() for PUD/PMD, which do not handle the large PAT bit properly. Fix __split_large_page() by using the corresponding pud/pmd pfn/ pgprot interfaces. Also remove '#ifdef CONFIG_X86_64', which is not necessary. Signed-off-by: Toshi Kani Cc: Andrew Morton Cc: Juergen Gross Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Borislav Petkov Cc: Konrad Wilk Cc: Robert Elliot Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/1442514264-12475-11-git-send-email-toshi.kani@hpe.com Signed-off-by: Thomas Gleixner --- arch/x86/mm/pageattr.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 3f612713159a..ab9465b9160f 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -605,7 +605,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, struct page *base) { pte_t *pbase = (pte_t *)page_address(base); - unsigned long pfn, pfninc = 1; + unsigned long ref_pfn, pfn, pfninc = 1; unsigned int i, level; pte_t *tmp; pgprot_t ref_prot; @@ -622,26 +622,33 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, } paravirt_alloc_pte(&init_mm, page_to_pfn(base)); - ref_prot = pte_pgprot(pte_clrhuge(*kpte)); - /* promote PAT bit to correct position */ - if (level == PG_LEVEL_2M) + switch (level) { + case PG_LEVEL_2M: + ref_prot = pmd_pgprot(*(pmd_t *)kpte); + /* clear PSE and promote PAT bit to correct position */ ref_prot = pgprot_large_2_4k(ref_prot); + ref_pfn = pmd_pfn(*(pmd_t *)kpte); + break; -#ifdef CONFIG_X86_64 - if (level == PG_LEVEL_1G) { + case PG_LEVEL_1G: + ref_prot = pud_pgprot(*(pud_t *)kpte); + ref_pfn = pud_pfn(*(pud_t *)kpte); pfninc = PMD_PAGE_SIZE >> PAGE_SHIFT; + /* - * Set the PSE flags only if the PRESENT flag is set + * Clear the PSE flags if the PRESENT flag is not set * otherwise pmd_present/pmd_huge will return true * even on a non present pmd. */ - if (pgprot_val(ref_prot) & _PAGE_PRESENT) - pgprot_val(ref_prot) |= _PAGE_PSE; - else + if (!(pgprot_val(ref_prot) & _PAGE_PRESENT)) pgprot_val(ref_prot) &= ~_PAGE_PSE; + break; + + default: + spin_unlock(&pgd_lock); + return 1; } -#endif /* * Set the GLOBAL flags only if the PRESENT flag is set @@ -657,7 +664,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, /* * Get the target pfn from the original entry: */ - pfn = pte_pfn(*kpte); + pfn = ref_pfn; for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot)));