x86/mm/pageattr: Add a PMD pagetable populating function

Handle PMD-level mappings the same as PUD ones.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 81 insertions, 1 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 81deca77b871..968398b023c0 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)