blob: 7dcd8729e5a817e1913cc29f911422634539c446 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
|
From e935ed6506f0753343bfc8adfa6f96922737af28 Mon Sep 17 00:00:00 2001
From: Jiri Kosina <jkosina@suse.cz>
Date: Tue, 2 Jan 2018 14:19:49 +0100
Subject: [PATCH 036/103] kaiser: disabled on Xen PV
Kaiser cannot be used on paravirtualized MMUs (namely reading and writing CR3).
This does not work with KAISER as the CR3 switch from and to user space PGD
would require to map the whole XEN_PV machinery into both.
More importantly, enabling KAISER on Xen PV doesn't make too much sense, as PV
guests use distinct %cr3 values for kernel and user already.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/mm/kaiser.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c
index 8600663..2768854 100644
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -263,6 +263,9 @@ void __init kaiser_check_boottime_disable(void)
char arg[5];
int ret;
+ if (boot_cpu_has(X86_FEATURE_XENPV))
+ goto silent_disable;
+
ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg));
if (ret > 0) {
if (!strncmp(arg, "on", 2))
@@ -290,6 +293,8 @@ void __init kaiser_check_boottime_disable(void)
disable:
pr_info("Kernel/User page tables isolation: disabled\n");
+
+silent_disable:
kaiser_enabled = 0;
setup_clear_cpu_cap(X86_FEATURE_KAISER);
}
--
2.7.4
|
