From 13c72c060f1ba6f4eddd7b1c4f52a8aded43d6d9 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 8 Jan 2020 12:24:39 -0800 Subject: [PATCH] x86/mm: Introduce lookup_address_in_mm() Add a helper, lookup_address_in_mm(), to traverse the page tables of a given mm struct. KVM will use the helper to retrieve the host mapping level, e.g. 4k vs. 2mb vs. 1gb, of a compound (or DAX-backed) page without having to resort to implementation specific metadata. E.g. KVM currently uses different logic for HugeTLB vs. THP, and would add a third variant for DAX-backed files. Cc: Dan Williams Signed-off-by: Sean Christopherson Reviewed-by: Thomas Gleixner Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/pgtable_types.h | 4 ++++ arch/x86/mm/pageattr.c | 11 +++++++++++ 2 files changed, 15 insertions(+) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index b5e49e6bac63..b68f72adb53e 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -561,6 +561,10 @@ static inline void update_page_count(int level, unsigned long pages) { } extern pte_t *lookup_address(unsigned long address, unsigned int *level); extern pte_t *lookup_address_in_pgd(pgd_t *pgd, unsigned long address, unsigned int *level); + +struct mm_struct; +extern pte_t *lookup_address_in_mm(struct mm_struct *mm, unsigned long address, + unsigned int *level); extern pmd_t *lookup_pmd_address(unsigned long address); extern phys_addr_t slow_virt_to_phys(void *__address); extern int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 1b99ad05b117..2c70a8b20b04 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -618,6 +618,17 @@ pte_t *lookup_address(unsigned long address, unsigned int *level) } EXPORT_SYMBOL_GPL(lookup_address); +/* + * Lookup the page table entry for a virtual address in a given mm. Return a + * pointer to the entry and the level of the mapping. + */ +pte_t *lookup_address_in_mm(struct mm_struct *mm, unsigned long address, + unsigned int *level) +{ + return lookup_address_in_pgd(pgd_offset(mm, address), address, level); +} +EXPORT_SYMBOL_GPL(lookup_address_in_mm); + static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address, unsigned int *level) {