[lkml]   [2020]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 05/14] 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 <>
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..400ac8da75e8 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;
+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 0d09cc5aad61..8787fec876e4 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)

+ * 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);
static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
unsigned int *level)
 \ /
  Last update: 2020-01-08 21:28    [W:0.119 / U:3.380 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site