pve-edge-kernel/patches/kernel/0076-x86-xen-Provide-pre-built-page-tables-only-for-CONFI.patch

From cac8711a9ba742e97090cc5ec522360f1549c584 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <[email protected]>
Date: Fri, 29 Sep 2017 17:08:19 +0300
Subject: [PATCH 076/242] x86/xen: Provide pre-built page tables only for
 CONFIG_XEN_PV=y and CONFIG_XEN_PVH=y
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CVE-2017-5754

Looks like we only need pre-built page tables in the CONFIG_XEN_PV=y and
CONFIG_XEN_PVH=y cases.

Let's not provide them for other configurations.

Signed-off-by: Kirill A. Shutemov <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Cyrill Gorcunov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
(cherry picked from commit 4375c29985f155d7eb2346615d84e62d1b673682)
Signed-off-by: Andy Whitcroft <[email protected]>
Signed-off-by: Kleber Sacilotto de Souza <[email protected]>
(cherry picked from commit a883ee7f3c1dc64a8c946543ac598399353d1b03)
Signed-off-by: Fabian Grünbichler <[email protected]>
---
 arch/x86/kernel/head_64.S | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index d081bc7a027d..12daaa0b187f 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -37,11 +37,12 @@
  *
  */
 
-#define p4d_index(x)	(((x) >> P4D_SHIFT) & (PTRS_PER_P4D-1))
 #define pud_index(x)	(((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
 
+#if defined(CONFIG_XEN_PV) || defined(CONFIG_XEN_PVH)
 PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE)
 PGD_START_KERNEL = pgd_index(__START_KERNEL_map)
+#endif
 L3_START_KERNEL = pud_index(__START_KERNEL_map)
 
 	.text
@@ -348,10 +349,7 @@ NEXT_PAGE(early_dynamic_pgts)
 
 	.data
 
-#ifndef CONFIG_XEN
-NEXT_PAGE(init_top_pgt)
-	.fill	512,8,0
-#else
+#if defined(CONFIG_XEN_PV) || defined(CONFIG_XEN_PVH)
 NEXT_PAGE(init_top_pgt)
 	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
 	.org    init_top_pgt + PGD_PAGE_OFFSET*8, 0
@@ -368,6 +366,9 @@ NEXT_PAGE(level2_ident_pgt)
 	 * Don't set NX because code runs from these pages.
 	 */
 	PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
+#else
+NEXT_PAGE(init_top_pgt)
+	.fill	512,8,0
 #endif
 
 #ifdef CONFIG_X86_5LEVEL
-- 
2.14.2