The current CONFIG_SPECULATION_MITIGATIONS namespace is only
halfway populated, where some mitigations have entries in Kconfig, and
they could be modified, while others mitigations do not have Kconfig
entries, and can not be controlled at build time.
New mitigations, such as BHI, were properly added, i.e, having an
independent Kconfig, which depends on CONFIG_SPECULATION_MITIGATIONS,
so, you can enable/disable at compilation time.
This patch set aims to have the old mitigations in the same format,
bringing some uniformity to the mitigations.
These are the advantages of having fine-grained control for the
mitigations:
1) Users can choose and pick only mitigations that are important for
their workloads.
2) Users and developers can choose to disable mitigations that mangle
the assembly code generation, making it hard to read.
3) Separate Kconfigs for just source code readability,
so that we see *which* butt-ugly piece of crap code is for what
reason...
In most cases, if a mitigation is disabled at compilation time, it
can still be enabled at runtime using kernel command line arguments.
This is the second part of the initial patchset[1] that got half landed.
The first patch did some code re-organization. This second part
contains the exact missing patches from the initial patchset, and
basically adds build-time configuration for the other mitigations that
are currently only disabled at boot time.
Here is a detailed view of each patch:
With this patch applied, setting CONFIG_SPECULATION_MITIGATIONS=n, a
simple script[2] shows that all the mitigations are disabled:
spectre_v2_user_stibp SPECTRE_V2_USER_NONE
spectre_v2_user_ibpb SPECTRE_V2_USER_NONE
spectre_v2_cmd SPECTRE_V2_CMD_NONE
ssb_mode SPEC_STORE_BYPASS_NONE
l1tf_mitigation L1TF_MITIGATION_OFF
srso_mitigation SRSO_MITIGATION_NONE
srso_cmd SRSO_CMD_SAFE_RET
mds_mitigation MDS_MITIGATION_OFF
taa_mitigation TAA_MITIGATION_OFF
mmio_mitigation MMIO_MITIGATION_OFF
srbds_mitigation SRBDS_MITIGATION_OFF
gds_mitigation GDS_MITIGATION_OFF
spectre_v1_mitigation SPECTRE_V1_MITIGATION_NONE
spectre_v2_enabled SPECTRE_V2_NONE
retbleed_mitigation RETBLEED_MITIGATION_NONE
[1] https://lore.kernel.org/all/[email protected]/#t
[2] https://github.com/leitao/debug/blob/main/spec/dump_speculation.py
Changelog:
v3:
* Rebased the patch on top of linux-next, since BHI mitigation added
some hunk to original patch series.
* Broke down the patches even further, creating one patch for each
mitigation. This make the review code easier (I hope).
* Nothing was changed, code-wise. The code is *exactly* the * same
* Dropped the "spectre_v2_user default mode depends on main default"
patch, that will be sent later, since there is no dependency to this
patch series. Hopping to make the review/acceptance easier as well.
v2:
* Patch 2: Changed `mode` type from int to `enum spectre_v2_user_cmd`
as suggested by Pawan Gupta
* Patch 3: Change MITIGATION_RETBLEED dependency to match the code.
* https://lore.kernel.org/all/[email protected]/
v1:
* https://lore.kernel.org/all/[email protected]/
Breno Leitao (10):
x86/bugs: Add a separate config for GDS
x86/bugs: Add a separate config for MDS
x86/bugs: Add a separate config for TAA
x86/bugs: Add a separate config for MMIO Stable Data
x86/bugs: Add a separate config for L1TF
x86/bugs: Add a separate config for RETBLEED
x86/bugs: Add a separate config for Spectre v1
x86/bugs: Add a separate config for SRBDS
x86/bugs: Add a separate config for Spectre V2
x86/bugs: Add a separate config for SSB
arch/x86/Kconfig | 117 +++++++++++++++++++++++++++++++++++--
arch/x86/kernel/cpu/bugs.c | 46 +++++++++------
2 files changed, 140 insertions(+), 23 deletions(-)
--
2.43.0
Currently there is no way to disable GDS mitigation at build time.
Disabling the current config option (GDS_MITIGATION_FORCE) does not
disable the mitigation, but set it to GDS_MITIGATION_FULL, which does
not disable it.
Create a new kernel config that allows GDS to be completely disabled,
similarly to the "gather_data_sampling=off" or "mitigations=off" kernel
command-line. Move the GDS_MITIGATION_FORCE under this new mitigation.
Now, there are three options for GDS mitigation:
* CONFIG_MITIGATION_GDS=n -> Mitigation disabled (New)
* CONFIG_MITIGATION_GDS=y -> Mitigation enabled (GDS_MITIGATION_FULL)
* CONFIG_GDS_MITIGATION_FORCE=y -> Forceful mitigation (disable AVX)
Suggested-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 16 +++++++++++-----
arch/x86/kernel/cpu/bugs.c | 7 ++++---
2 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a902680b6537..d99b758c8d35 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2607,15 +2607,21 @@ config MITIGATION_SLS
against straight line speculation. The kernel image might be slightly
larger.
+config MITIGATION_GDS
+ bool "Mitigate Gather Data Sampling"
+ depends on CPU_SUP_INTEL
+ default y
+ help
+ Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
+ vulnerability which allows unprivileged speculative access to data
+ which was previously stored in vector registers. The attacker uses gather
+ instructions to infer the stale vector register data.
+
config MITIGATION_GDS_FORCE
bool "Force GDS Mitigation"
- depends on CPU_SUP_INTEL
+ depends on MITIGATION_GDS
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
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 9a9685c9244b..f2bdfb359f6b 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -731,10 +731,11 @@ enum gds_mitigations {
GDS_MITIGATION_HYPERVISOR,
};
-#if IS_ENABLED(CONFIG_MITIGATION_GDS_FORCE)
-static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FORCE;
+#if IS_ENABLED(CONFIG_MITIGATION_GDS)
+static enum gds_mitigations gds_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_GDS_FORCE) ? GDS_MITIGATION_FORCE : GDS_MITIGATION_FULL;
#else
-static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FULL;
+static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_OFF;
#endif
static const char * const gds_strings[] = {
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the MDS CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 9 +++++++++
arch/x86/kernel/cpu/bugs.c | 3 ++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d99b758c8d35..5d0227b50faa 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2653,6 +2653,15 @@ config MITIGATION_SPECTRE_BHI
indirect branches.
See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
+config MITIGATION_MDS
+ bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
+ depends on CPU_SUP_INTEL
+ default y
+ help
+ Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
+ a hardware vulnerability which allows unprivileged speculative access
+ to data which is available in various CPU internal buffers.
+ See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index f2bdfb359f6b..fb6515b1b33e 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -233,7 +233,8 @@ static void x86_amd_ssb_disable(void)
#define pr_fmt(fmt) "MDS: " fmt
/* Default mitigation for MDS-affected CPUs */
-static enum mds_mitigations mds_mitigation __ro_after_init = MDS_MITIGATION_FULL;
+static enum mds_mitigations mds_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_MDS) ? MDS_MITIGATION_FULL : MDS_MITIGATION_OFF;
static bool mds_nosmt __ro_after_init = false;
static const char * const mds_strings[] = {
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the RETBLEED CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 13 +++++++++++++
arch/x86/kernel/cpu/bugs.c | 2 +-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 192d20348b41..f5c941a0a837 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2695,6 +2695,19 @@ config MITIGATION_L1TF
hardware vulnerability which allows unprivileged speculative access to data
available in the Level 1 Data Cache.
See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
+
+config MITIGATION_RETBLEED
+ bool "Mitigate RETBleed hardware bug"
+ depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
+ default y
+ help
+ Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
+ with Return Instructions) vulnerability. RETBleed is a speculative
+ execution attack which takes advantage of microarchitectural behavior
+ in many modern microprocessors, similar to Spectre v2. An
+ unprivileged attacker can use these flaws to bypass conventional
+ memory security restrictions to gain read access to privileged memory
+ that would otherwise be inaccessible.
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d20299b350d7..c6c404b1c6ac 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -990,7 +990,7 @@ static const char * const retbleed_strings[] = {
static enum retbleed_mitigation retbleed_mitigation __ro_after_init =
RETBLEED_MITIGATION_NONE;
static enum retbleed_mitigation_cmd retbleed_cmd __ro_after_init =
- RETBLEED_CMD_AUTO;
+ IS_ENABLED(CONFIG_MITIGATION_RETBLEED) ? RETBLEED_CMD_AUTO : RETBLEED_CMD_OFF;
static int __ro_after_init retbleed_nosmt = false;
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the Spectre v1 CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 10 ++++++++++
arch/x86/kernel/cpu/bugs.c | 3 ++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f5c941a0a837..43dd45720fb1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2708,6 +2708,16 @@ config MITIGATION_RETBLEED
unprivileged attacker can use these flaws to bypass conventional
memory security restrictions to gain read access to privileged memory
that would otherwise be inaccessible.
+
+config MITIGATION_SPECTRE_V1
+ bool "Mitigate SPECTRE V1 hardware bug"
+ default y
+ help
+ Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
+ class of side channel attacks that takes advantage of speculative
+ execution that bypasses conditional branch instructions used for
+ memory access bounds check.
+ See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index c6c404b1c6ac..00c3438519be 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -875,7 +875,8 @@ enum spectre_v1_mitigation {
};
static enum spectre_v1_mitigation spectre_v1_mitigation __ro_after_init =
- SPECTRE_V1_MITIGATION_AUTO;
+ IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V1) ?
+ SPECTRE_V1_MITIGATION_AUTO : SPECTRE_V1_MITIGATION_NONE;
static const char * const spectre_v1_strings[] = {
[SPECTRE_V1_MITIGATION_NONE] = "Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers",
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the SRBDS CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 14 ++++++++++++++
arch/x86/kernel/cpu/bugs.c | 3 ++-
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 43dd45720fb1..fdf1c894fcb8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2718,6 +2718,20 @@ config MITIGATION_SPECTRE_V1
execution that bypasses conditional branch instructions used for
memory access bounds check.
See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
+
+config MITIGATION_SRBDS
+ bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
+ depends on CPU_SUP_INTEL
+ default y
+ help
+ Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
+ SRBDS is a hardware vulnerability that allows Microarchitectural Data
+ Sampling (MDS) techniques to infer values returned from special
+ register accesses. An unprivileged user can extract values returned
+ from RDRAND and RDSEED executed on another core or sibling thread
+ using MDS techniques.
+ See also
+ <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 00c3438519be..49b60c0e2eb4 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -608,7 +608,8 @@ enum srbds_mitigations {
SRBDS_MITIGATION_HYPERVISOR,
};
-static enum srbds_mitigations srbds_mitigation __ro_after_init = SRBDS_MITIGATION_FULL;
+static enum srbds_mitigations srbds_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_SRBDS) ? SRBDS_MITIGATION_FULL : SRBDS_MITIGATION_OFF;
static const char * const srbds_strings[] = {
[SRBDS_MITIGATION_OFF] = "Vulnerable",
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the TAA CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 11 +++++++++++
arch/x86/kernel/cpu/bugs.c | 3 ++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5d0227b50faa..c7ce800fcdb2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2662,6 +2662,17 @@ config MITIGATION_MDS
a hardware vulnerability which allows unprivileged speculative access
to data which is available in various CPU internal buffers.
See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
+
+config MITIGATION_TAA
+ bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
+ depends on CPU_SUP_INTEL
+ default y
+ help
+ Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
+ vulnerability that allows unprivileged speculative access to data
+ which is available in various CPU internal buffers by using
+ asynchronous aborts within an Intel TSX transactional region.
+ See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index fb6515b1b33e..87f3cc6c438d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -294,7 +294,8 @@ enum taa_mitigations {
};
/* Default mitigation for TAA-affected CPUs */
-static enum taa_mitigations taa_mitigation __ro_after_init = TAA_MITIGATION_VERW;
+static enum taa_mitigations taa_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_TAA) ? TAA_MITIGATION_VERW : TAA_MITIGATION_OFF;
static bool taa_nosmt __ro_after_init;
static const char * const taa_strings[] = {
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the MMIO Stale data CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 12 ++++++++++++
arch/x86/kernel/cpu/bugs.c | 3 ++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c7ce800fcdb2..bba5b65034dc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2673,6 +2673,18 @@ config MITIGATION_TAA
which is available in various CPU internal buffers by using
asynchronous aborts within an Intel TSX transactional region.
See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
+
+config MITIGATION_MMIO_STALE_DATA
+ bool "Mitigate MMIO Stale Data hardware bug"
+ depends on CPU_SUP_INTEL
+ default y
+ help
+ Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO
+ Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
+ vulnerabilities that can expose data. The vulnerabilities require the
+ attacker to have access to MMIO.
+ See also
+ <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 87f3cc6c438d..21daaf202b7f 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -393,7 +393,8 @@ enum mmio_mitigations {
};
/* Default mitigation for Processor MMIO Stale Data vulnerabilities */
-static enum mmio_mitigations mmio_mitigation __ro_after_init = MMIO_MITIGATION_VERW;
+static enum mmio_mitigations mmio_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_MMIO_STALE_DATA) ? MMIO_MITIGATION_VERW : MMIO_MITIGATION_OFF;
static bool mmio_nosmt __ro_after_init = false;
static const char * const mmio_strings[] = {
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the L1TF CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 10 ++++++++++
arch/x86/kernel/cpu/bugs.c | 3 ++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bba5b65034dc..192d20348b41 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2685,6 +2685,16 @@ config MITIGATION_MMIO_STALE_DATA
attacker to have access to MMIO.
See also
<file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
+
+config MITIGATION_L1TF
+ bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
+ depends on CPU_SUP_INTEL
+ default y
+ help
+ Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
+ hardware vulnerability which allows unprivileged speculative access to data
+ available in the Level 1 Data Cache.
+ See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 21daaf202b7f..d20299b350d7 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2373,7 +2373,8 @@ EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation);
#define pr_fmt(fmt) "L1TF: " fmt
/* Default mitigation for L1TF-affected CPUs */
-enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
+enum l1tf_mitigations l1tf_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_L1TF) ? L1TF_MITIGATION_FLUSH : L1TF_MITIGATION_OFF;
#if IS_ENABLED(CONFIG_KVM_INTEL)
EXPORT_SYMBOL_GPL(l1tf_mitigation);
#endif
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the Spectre V2 CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 12 ++++++++++++
arch/x86/kernel/cpu/bugs.c | 9 +++++----
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fdf1c894fcb8..4f69a7f5f675 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2719,6 +2719,18 @@ config MITIGATION_SPECTRE_V1
memory access bounds check.
See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
+config MITIGATION_SPECTRE_V2
+ bool "Mitigate SPECTRE V2 hardware bug"
+ default y
+ help
+ Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
+ V2 is a class of side channel attacks that takes advantage of
+ indirect branch predictors inside the processor. In Spectre variant 2
+ attacks, the attacker can steer speculative indirect branches in the
+ victim to gadget code by poisoning the branch target buffer of a CPU
+ used for predicting indirect branch addresses.
+ See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
+
config MITIGATION_SRBDS
bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
depends on CPU_SUP_INTEL
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 49b60c0e2eb4..5628a77281fe 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1457,17 +1457,18 @@ static void __init spec_v2_print_cond(const char *reason, bool secure)
static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
{
- enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO;
+ enum spectre_v2_mitigation_cmd cmd;
char arg[20];
int ret, i;
+ cmd = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO : SPECTRE_V2_CMD_NONE;
if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") ||
cpu_mitigations_off())
return SPECTRE_V2_CMD_NONE;
ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
if (ret < 0)
- return SPECTRE_V2_CMD_AUTO;
+ return cmd;
for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
if (!match_option(arg, ret, mitigation_options[i].option))
@@ -1477,8 +1478,8 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
}
if (i >= ARRAY_SIZE(mitigation_options)) {
- pr_err("unknown option (%s). Switching to AUTO select\n", arg);
- return SPECTRE_V2_CMD_AUTO;
+ pr_err("unknown option (%s). Switching to default mode\n", arg);
+ return cmd;
}
if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
--
2.43.0
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.
Create an entry for the SSB CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.
Signed-off-by: Breno Leitao <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
---
arch/x86/Kconfig | 10 ++++++++++
arch/x86/kernel/cpu/bugs.c | 10 ++++++----
2 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4f69a7f5f675..8a5fcb1468f0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2744,6 +2744,16 @@ config MITIGATION_SRBDS
using MDS techniques.
See also
<file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
+
+config MITIGATION_SSB
+ bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
+ default y
+ help
+ Enable mitigation for Speculative Store Bypass (SSB). SSB is a
+ hardware security vulnerability and its exploitation takes advantage
+ of speculative execution in a similar way to the Meltdown and Spectre
+ security vulnerabilities.
+
endif
config ARCH_HAS_ADD_PAGES
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 5628a77281fe..2e8b24e36d01 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2026,10 +2026,12 @@ static const struct {
static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
{
- enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
+ enum ssb_mitigation_cmd cmd;
char arg[20];
int ret, i;
+ cmd = IS_ENABLED(CONFIG_MITIGATION_SSB) ?
+ SPEC_STORE_BYPASS_CMD_AUTO : SPEC_STORE_BYPASS_CMD_NONE;
if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
cpu_mitigations_off()) {
return SPEC_STORE_BYPASS_CMD_NONE;
@@ -2037,7 +2039,7 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
arg, sizeof(arg));
if (ret < 0)
- return SPEC_STORE_BYPASS_CMD_AUTO;
+ return cmd;
for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
if (!match_option(arg, ret, ssb_mitigation_options[i].option))
@@ -2048,8 +2050,8 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
}
if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
- pr_err("unknown option (%s). Switching to AUTO select\n", arg);
- return SPEC_STORE_BYPASS_CMD_AUTO;
+ pr_err("unknown option (%s). Switching to default mode\n", arg);
+ return cmd;
}
}
--
2.43.0