[PATCH 1/3] x86/mm: do not attempt to convert _PAGE_GNTTAB to a boolean

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Clang 10 complains with:

mm.c:1239:10: error: converting the result of '<<' to a boolean always 
evaluates to true
      [-Werror,-Wtautological-constant-compare]
    if ( _PAGE_GNTTAB && (l1e_get_flags(l1e) & _PAGE_GNTTAB) &&
         ^
xen/include/asm/x86_64/page.h:161:25: note: expanded from macro '_PAGE_GNTTAB'
#define _PAGE_GNTTAB (1U<<22)
                        ^

Remove the conversion of _PAGE_GNTTAB to a boolean, since the and
operation performed afterwards will already return false if the value
of the macro is 0.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/mm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 355c50ff91..27069d2451 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -1236,7 +1236,7 @@ void put_page_from_l1e(l1_pgentry_t l1e, struct domain 
*l1e_owner)
      * (Note that the undestroyable active grants are not a security hole in
      * Xen. All active grants can safely be cleaned up when the domain dies.)
      */
-    if ( _PAGE_GNTTAB && (l1e_get_flags(l1e) & _PAGE_GNTTAB) &&
+    if ( (l1e_get_flags(l1e) & _PAGE_GNTTAB) &&
          !l1e_owner->is_shutting_down && !l1e_owner->is_dying )
     {
         gdprintk(XENLOG_WARNING,
-- 
2.26.2