x86/pti/efi: broken conversion from efi to kernel page table

The page table order must be increased for EFI table in order to avoid a
bug where NMI tries to change the page table to kernel page table, while
efi page table is active.

For more disccussion about this bug, see this thread:
http://lkml.iu.edu/hypermail/linux/kernel/1801.1/00951.html

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index b6d4259..1178a51 100644 (file)
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -27,6 +27,17 @@ static inline void paravirt_release_pud(unsigned long pfn) {}
  */
 extern gfp_t __userpte_alloc_gfp;
 
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+/*
+ * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
+ * both 8k in size and 8k-aligned.  That lets us just flip bit 12
+ * in a pointer to swap between the two 4k halves.
+ */
+#define PGD_ALLOCATION_ORDER 1
+#else
+#define PGD_ALLOCATION_ORDER 0
+#endif
+
 /*
  * Allocate and free page tables.
  */

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 5aaec8e..209b946 100644 (file)
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -345,13 +345,6 @@ static inline void _pgd_free(pgd_t *pgd)
 }
 #else
 
-/*
- * Instead of one pgd, Kaiser acquires two pgds.  Being order-1, it is
- * both 8k in size and 8k-aligned.  That lets us just flip bit 12
- * in a pointer to swap between the two 4k halves.
- */
-#define PGD_ALLOCATION_ORDER   kaiser_enabled
-
 static inline pgd_t *_pgd_alloc(void)
 {
        return (pgd_t *)__get_free_pages(PGALLOC_GFP, PGD_ALLOCATION_ORDER);

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 2f25a36..dcb2d9d 100644 (file)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -142,7 +142,7 @@ int __init efi_alloc_page_tables(void)
                return 0;
 
        gfp_mask = GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO;
-       efi_pgd = (pgd_t *)__get_free_page(gfp_mask);
+       efi_pgd = (pgd_t *)__get_free_pages(gfp_mask, PGD_ALLOCATION_ORDER);
        if (!efi_pgd)
                return -ENOMEM;