[PATCH 06/11] x86, pageattr: Add a PMD pagetable populating function

Borislav Petkov
2013-09-19T14:54:49Z

From: Borislav Petkov <bp@suse.de>

Handle PMD-level mappings the same as PUD ones.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/mm/pageattr.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 81 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 41c6fdbbfab0..c56d71591617 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -666,6 +666,16 @@ static int split_large_page(pte_t *kpte, unsigned long address)
return 0;
}

+static int alloc_pte_page(pmd_t *pmd)
+{
+ pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK);
+ if (!pte)
+ return -1;
+
+ set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
+ return 0;
+}
+
static int alloc_pmd_page(pud_t *pud)
{
pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK);
@@ -676,7 +686,77 @@ static int alloc_pmd_page(pud_t *pud)
return 0;
}

-#define populate_pmd(cpa, start, end, pages, pud, pgprot) (-1)
+#define populate_pte(cpa, start, end, pages, pmd, pgprot) do {} while (0)
+
+static int populate_pmd(struct cpa_data *cpa,
+ unsigned long start, unsigned long end,
+ unsigned num_pages, pud_t *pud, pgprot_t pgprot)
+{
+ unsigned int cur_pages = 0;
+ pmd_t *pmd;
+
+ /*
+ * Not on a 2M boundary?
+ */
+ if (start & (PMD_SIZE - 1)) {
+ unsigned long pre_end = start + (num_pages << PAGE_SHIFT);
+ unsigned long next_page = (start + PMD_SIZE) & PMD_MASK;
+
+ pre_end = min_t(unsigned long, pre_end, next_page);
+ cur_pages = (pre_end - start) >> PAGE_SHIFT;
+ cur_pages = min_t(unsigned int, num_pages, cur_pages);
+
+ /*
+ * Need a PTE page?
+ */
+ pmd = pmd_offset(pud, start);
+ if (pmd_none(*pmd))
+ if (alloc_pte_page(pmd))
+ return -1;
+
+ populate_pte(cpa, start, pre_end, cur_pages, pmd, pgprot);
+
+ start = pre_end;
+ }
+
+ /*
+ * We mapped them all?
+ */
+ if (num_pages == cur_pages)
+ return cur_pages;
+
+ while (end - start >= PMD_SIZE) {
+
+ /*
+ * We cannot use a 1G page so allocate a PMD page if needed.
+ */
+ if (pud_none(*pud))
+ if (alloc_pmd_page(pud))
+ return -1;
+
+ pmd = pmd_offset(pud, start);
+
+ set_pmd(pmd, __pmd(cpa->pfn | _PAGE_PSE | massage_pgprot(pgprot)));
+
+ start += PMD_SIZE;
+ cpa->pfn += PMD_SIZE;
+ cur_pages += PMD_SIZE >> PAGE_SHIFT;
+ }
+
+ /*
+ * Map trailing 4K pages.
+ */
+ if (start < end) {
+ pmd = pmd_offset(pud, start);
+ if (pmd_none(*pmd))
+ if (alloc_pte_page(pmd))
+ return -1;
+
+ populate_pte(cpa, start, end, num_pages - cur_pages,
+ pmd, pgprot);
+ }
+ return num_pages;
+}

static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd,
pgprot_t pgprot)
--
1.8.4