[PATCH 2/8] x86/boot: Better describe the pagetable relocation loops

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The first loop relocates all reachable non-leaf entries in idle_pg_table[],
which includes l2_xenmap[511]'s reference to l1_fixmap_x[].

The second loop relocates only leaf mappings in l2_xenmap[], so update the
skip condition to be opposite to the first loop.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
---
 xen/arch/x86/setup.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 6f241048425c..495b4b7d51fb 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1245,7 +1245,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
             barrier();
             move_memory(e, XEN_IMG_OFFSET, _end - _start, 1);
 
-            /* Walk initial pagetables, relocating page directory entries. */
+            /* Walk idle_pg_table, relocating non-leaf entries. */
             pl4e = __va(__pa(idle_pg_table));
             for ( i = 0 ; i < L4_PAGETABLE_ENTRIES; i++, pl4e++ )
             {
@@ -1277,18 +1277,18 @@ void __init noreturn __start_xen(unsigned long mbi_p)
                 }
             }
 
-            /* The only data mappings to be relocated are in the Xen area. */
-            pl2e = __va(__pa(l2_xenmap));
-
             BUG_ON(using_2M_mapping() &&
                    l2_table_offset((unsigned long)_erodata) ==
                    l2_table_offset((unsigned long)_stext));
 
+            /* Walk l2_xenmap[], relocating 2M superpage leaves. */
+            pl2e = __va(__pa(l2_xenmap));
             for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++, pl2e++ )
             {
                 unsigned int flags;
 
                 if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) ||
+                     !(l2e_get_flags(*pl2e) & _PAGE_PSE) ||
                      (l2e_get_pfn(*pl2e) >= pte_update_limit) )
                     continue;
 
-- 
2.11.0