x86/mm/pageattr: Use __KERNEL_PAGE_EXEC for kernel pgtable

_KERNPG_TABLE isn't the correct pgprot value to use for the PTE, it's
only suitable for the upper levels of the page table structures
(TRUE?).

One benefit is that _PAGE_GLOBAL is now set in the ptes created in
kernel_map_pages_in_pgd() just like if large pages get split later.

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

arch/x86/mm/pageattr.c

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 58653ae..427dfb0 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -881,6 +881,22 @@
 
 	pte = pte_offset_kernel(pmd, start);
 
+#if 0
+	pgprot_val(pgprot) = __PAGE_KERNEL;
+
+	/*
+	 * Set the GLOBAL flags only if the PRESENT flag is
+	 * set otherwise pte_present will return true even on
+	 * a non present pte. The canon_pgprot will clear
+	 * _PAGE_GLOBAL for the ancient hardware that doesn't
+	 * support it.
+	 */
+	if (pgprot_val(pgprot) & _PAGE_PRESENT)
+		pgprot_val(pgprot) |= _PAGE_GLOBAL;
+	else
+		pgprot_val(pgprot) &= ~_PAGE_GLOBAL;
+#endif
+
 	while (num_pages-- && start < end) {
 
 		/* deal with the NX bit */