blob: 5d01d4fa9a4e1c964f9bcc72756667cc446333bd (
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
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
From dc9710d3e8c3a26fbd764f4bd733814c9464bf31 Mon Sep 17 00:00:00 2001
From: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Date: Wed, 12 Jul 2023 19:43:13 -0700
Subject: x86/speculation: Add Kconfig option for GDS
From: Daniel Sneddon <daniel.sneddon@linux.intel.com>
commit 53cf5797f114ba2bd86d23a862302119848eff19 upstream
Gather Data Sampling (GDS) is mitigated in microcode. However, on
systems that haven't received the updated microcode, disabling AVX
can act as a mitigation. Add a Kconfig option that uses the microcode
mitigation if available and disables AVX otherwise. Setting this
option has no effect on systems not affected by GDS. This is the
equivalent of setting gather_data_sampling=force.
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/Kconfig | 19 +++++++++++++++++++
arch/x86/kernel/cpu/bugs.c | 4 ++++
2 files changed, 23 insertions(+)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2438,6 +2438,25 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
def_bool y
depends on X86_64 || X86_PAE
+config GDS_FORCE_MITIGATION
+ bool "Force GDS Mitigation"
+ depends on CPU_SUP_INTEL
+ default n
+ help
+ Gather Data Sampling (GDS) is a hardware vulnerability which allows
+ unprivileged speculative access to data which was previously stored in
+ vector registers.
+
+ This option is equivalent to setting gather_data_sampling=force on the
+ command line. The microcode mitigation is used if present, otherwise
+ AVX is disabled as a mitigation. On affected systems that are missing
+ the microcode any userspace code that unconditionally uses AVX will
+ break with this option set.
+
+ Setting this option on systems not vulnerable to GDS has no effect.
+
+ If in doubt, say N.
+
config ARCH_ENABLE_HUGEPAGE_MIGRATION
def_bool y
depends on X86_64 && HUGETLB_PAGE && MIGRATION
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -613,7 +613,11 @@ enum gds_mitigations {
GDS_MITIGATION_HYPERVISOR,
};
+#if IS_ENABLED(CONFIG_GDS_FORCE_MITIGATION)
+static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FORCE;
+#else
static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FULL;
+#endif
static const char * const gds_strings[] = {
[GDS_MITIGATION_OFF] = "Vulnerable",
|
