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authorThomas Gleixner <tglx@linutronix.de>2018-11-25 19:33:45 +0100
committerThomas Gleixner <tglx@linutronix.de>2018-11-28 11:57:10 +0100
commitfa1202ef224391b6f5b26cdd44cc50495e8fab54 (patch)
treedc71e78238239673dcafda0a7e0b58b305423921 /Documentation
parentx86/speculation: Unify conditional spectre v2 print functions (diff)
downloadlinux-fa1202ef224391b6f5b26cdd44cc50495e8fab54.tar.xz
linux-fa1202ef224391b6f5b26cdd44cc50495e8fab54.zip
x86/speculation: Add command line control for indirect branch speculation
Add command line control for user space indirect branch speculation mitigations. The new option is: spectre_v2_user= The initial options are: - on: Unconditionally enabled - off: Unconditionally disabled -auto: Kernel selects mitigation (default off for now) When the spectre_v2= command line argument is either 'on' or 'off' this implies that the application to application control follows that state even if a contradicting spectre_v2_user= argument is supplied. Originally-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Casey Schaufler <casey.schaufler@intel.com> Cc: Asit Mallick <asit.k.mallick@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Jon Masters <jcm@redhat.com> Cc: Waiman Long <longman9394@gmail.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Dave Stewart <david.c.stewart@intel.com> Cc: Kees Cook <keescook@chromium.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181125185005.082720373@linutronix.de
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt32
1 files changed, 30 insertions, 2 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 19f4423e70d9..b6e5b33b9d75 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4194,9 +4194,13 @@
spectre_v2= [X86] Control mitigation of Spectre variant 2
(indirect branch speculation) vulnerability.
+ The default operation protects the kernel from
+ user space attacks.
- on - unconditionally enable
- off - unconditionally disable
+ on - unconditionally enable, implies
+ spectre_v2_user=on
+ off - unconditionally disable, implies
+ spectre_v2_user=off
auto - kernel detects whether your CPU model is
vulnerable
@@ -4206,6 +4210,12 @@
CONFIG_RETPOLINE configuration option, and the
compiler with which the kernel was built.
+ Selecting 'on' will also enable the mitigation
+ against user space to user space task attacks.
+
+ Selecting 'off' will disable both the kernel and
+ the user space protections.
+
Specific mitigations can also be selected manually:
retpoline - replace indirect branches
@@ -4215,6 +4225,24 @@
Not specifying this option is equivalent to
spectre_v2=auto.
+ spectre_v2_user=
+ [X86] Control mitigation of Spectre variant 2
+ (indirect branch speculation) vulnerability between
+ user space tasks
+
+ on - Unconditionally enable mitigations. Is
+ enforced by spectre_v2=on
+
+ off - Unconditionally disable mitigations. Is
+ enforced by spectre_v2=off
+
+ auto - Kernel selects the mitigation depending on
+ the available CPU features and vulnerability.
+ Default is off.
+
+ Not specifying this option is equivalent to
+ spectre_v2_user=auto.
+
spec_store_bypass_disable=
[HW] Control Speculative Store Bypass (SSB) Disable mitigation
(Speculative Store Bypass vulnerability)