lguest: use PGDIR_SHIFT for PAE code to allow different PAGE_OFFSET

We still assume the Guest and Host have the same PAGE_OFFSET settings,
but now we don't assume 0xC0000000.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Matias Zabaljauregui <zabaljauregui@gmail.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index 232fba6a4882..bf37a31c0e05 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -996,11 +996,9 @@ static unsigned long setup_pagetables(struct lguest *lg,
         if (copy_to_user(&pgdir[0], &pgd, sizeof(pgd)) != 0)
                 return -EFAULT;
         /*
-         * And the third PGD entry (ie. addresses 3G-4G).
-         *
-         * FIXME: This assumes that PAGE_OFFSET for the Guest is 0xC0000000.
+         * And the other PGD entry to make the linear mapping at PAGE_OFFSET
          */
-        if (copy_to_user(&pgdir[3], &pgd, sizeof(pgd)) != 0)
+        if (copy_to_user(&pgdir[KERNEL_PGD_BOUNDARY], &pgd, sizeof(pgd)))
                 return -EFAULT;
 #else
         /*