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

[~andy/linux] / arch / x86 / mm / pageattr.c

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index c53de62a117066e6358e4640ba87d029cac0fd37..4b47ae0602e110b1e0039ed2b7e358299e3c3473 100644 (file)
--- 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)
 {