Mailing List Archive

commit 3099ff3ce15481b4f1536470cb87ac0ebf82b7bb
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Mon Nov 29 19:19:43 2021 +0000
Commit: Andrew Cooper <andrew.cooper3@citrix.com>
CommitDate: Thu Dec 2 20:02:55 2021 +0000

x86/boot: Better describe the pagetable relocation loops

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@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
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 6f24104842..495b4b7d51 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;

--
generated by git-patchbot for /home/xen/git/xen.git#staging