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

Add the next level of the pagetable populating function, we handle
chunks around a 1G boundary by mapping them with the lower level
functions - otherwise we use 1G pages for the mappings, thus using as
less amount of pagetable pages as possible.

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

1 files changed, 86 insertions, 1 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 4b47ae0602e1..81deca77b871 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -666,7 +666,92 @@ static int split_large_page(pte_t *kpte, unsigned long address)
         return 0;
 }
 
-#define populate_pud(cpa, addr, pgd, pgprot)    (-1)
+static int alloc_pmd_page(pud_t *pud)
+{
+        pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK);
+        if (!pmd)
+                return -1;
+
+        set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
+        return 0;
+}
+
+#define populate_pmd(cpa, start, end, pages, pud, pgprot)       (-1)
+
+static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd,
+                        pgprot_t pgprot)
+{
+        pud_t *pud;
+        unsigned long end;
+        int cur_pages = 0;
+
+        end = start + (cpa->numpages << PAGE_SHIFT);
+
+        /*
+         * Not on a Gb page boundary? => map everything up to it with
+         * smaller pages.
+         */
+        if (start & (PUD_SIZE - 1)) {
+                unsigned long pre_end;
+                unsigned long next_page = (start + PUD_SIZE) & PUD_MASK;
+
+                pre_end   = min_t(unsigned long, end, next_page);
+                cur_pages = (pre_end - start) >> PAGE_SHIFT;
+                cur_pages = min_t(int, (int)cpa->numpages, cur_pages);
+
+                pud = pud_offset(pgd, start);
+
+                /*
+                 * Need a PMD page?
+                 */
+                if (pud_none(*pud))
+                        if (alloc_pmd_page(pud))
+                                return -1;
+
+                cur_pages = populate_pmd(cpa, start, pre_end, cur_pages,
+                                         pud, pgprot);
+                if (cur_pages < 0)
+                        return cur_pages;
+
+                start = pre_end;
+        }
+
+        /* We mapped them all? */
+        if (cpa->numpages == cur_pages)
+                return cur_pages;
+
+        pud = pud_offset(pgd, start);
+
+        /*
+         * Map everything starting from the Gb boundary, possibly with 1G pages
+         */
+        while (end - start >= PUD_SIZE) {
+                set_pud(pud, __pud(cpa->pfn | _PAGE_PSE | massage_pgprot(pgprot)));
+
+                start     += PUD_SIZE;
+                cpa->pfn  += PUD_SIZE;
+                cur_pages += PUD_SIZE >> PAGE_SHIFT;
+                pud++;
+        }
+
+        /* Map trailing leftover */
+        if (start < end) {
+                int tmp;
+
+                pud = pud_offset(pgd, start);
+                if (pud_none(*pud))
+                        if (alloc_pmd_page(pud))
+                                return -1;
+
+                tmp = populate_pmd(cpa, start, end, cpa->numpages - cur_pages,
+                                   pud, pgprot);
+                if (tmp < 0)
+                        return cur_pages;
+
+                cur_pages += tmp;
+        }
+        return cur_pages;
+}
 
 /*
  * Restrictions for kernel page table do not necessarily apply when mapping in