1 files changed, 39 insertions, 0 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index c53de62a1170..4b47ae0602e1 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -666,6 +666,45 @@ static int split_large_page(pte_t *kpte, unsigned long address)
         return 0;
 }
 
+#define populate_pud(cpa, addr, pgd, pgprot)    (-1)
+
+/*
+ * Restrictions for kernel page table do not necessarily apply when mapping in
+ * an alternate PGD.
+ */
+static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
+{
+        pgprot_t pgprot = __pgprot(_KERNPG_TABLE);
+        bool allocd_pgd = false;
+        pgd_t *pgd_entry;
+        pud_t *pud = NULL;      /* shut up gcc */
+        int ret;
+
+        pgd_entry = cpa->pgd + pgd_index(addr);
+
+        /*
+         * Allocate a PUD page and hand it down for mapping.
+         */
+        if (pgd_none(*pgd_entry)) {
+                pud = (pud_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK);
+                if (!pud)
+                        return -1;
+
+                set_pgd(pgd_entry, __pgd(__pa(pud) | _KERNPG_TABLE));
+                allocd_pgd = true;
+        }
+
+        pgprot_val(pgprot) &= ~pgprot_val(cpa->mask_clr);
+        pgprot_val(pgprot) |=  pgprot_val(cpa->mask_set);
+
+        ret = populate_pud(cpa, addr, pgd_entry, pgprot);
+        if (ret < 0)
+                return ret;
+
+        cpa->numpages = ret;
+        return 0;
+}
+
 static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
                                int primary)
 {