bootstrap_map_addr() needs to be careful to not remove existing page-table
structures when tearing down mappings, as such pagetable structures might be
needed to fulfill subsequent mappings requests.  The comment ahead of the
function already notes that pagetable memory shouldn't be allocated.

Fix this by using map_pages_to_xen(), which does zap the page-table entries,
but does not free page-table structures even when empty.

Fixes: 4376c05c3113 ('x86-64: use 1GB pages in 1:1 mapping if available')
Signed-off-by: Roger Pau Monné <roger.pau@ctrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
Changes since v1:
 - Adjust commit message.
---
 xen/arch/x86/setup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 4feef9f2e05a..5da1c6a34519 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -462,7 +462,9 @@ static void *__init bootstrap_map_addr(paddr_t start, paddr_t end)
 
     if ( !end )
     {
-        destroy_xen_mappings(BOOTSTRAP_MAP_BASE, BOOTSTRAP_MAP_LIMIT);
+        map_pages_to_xen(BOOTSTRAP_MAP_BASE, INVALID_MFN,
+                         PFN_DOWN(map_cur - BOOTSTRAP_MAP_BASE),
+                         _PAGE_NONE);
         map_cur = BOOTSTRAP_MAP_BASE;
         return NULL;
     }
-- 
2.46.0