0038-x86-mm-fix-detection-of-last-L1-entry-in-modify_xen_.patch


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From 1f94117bec55a7b934fed3dfd3529db624eb441f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com>
Date: Tue, 12 Mar 2024 12:08:59 +0100
Subject: [PATCH 38/67] x86/mm: fix detection of last L1 entry in
 modify_xen_mappings_lite()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The current logic to detect when to switch to the next L1 table is incorrectly
using l2_table_offset() in order to notice when the last entry on the current
L1 table has been reached.

It should instead use l1_table_offset() to check whether the index has wrapped
to point to the first entry, and so the next L1 table should be used.

Fixes: 8676092a0f16 ('x86/livepatch: Fix livepatch application when CET is active')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 7c81558208de7858251b62f168a449be84305595
master date: 2024-03-11 11:09:42 +0000
---
 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 e884a6fdbd..330c4abcd1 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5963,7 +5963,7 @@ void init_or_livepatch modify_xen_mappings_lite(
 
                 v += 1UL << L1_PAGETABLE_SHIFT;
 
-                if ( l2_table_offset(v) == 0 )
+                if ( l1_table_offset(v) == 0 )
                     break;
             }
 
-- 
2.44.0