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x86/speculation: Add command line control for indirect branch speculation

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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
This commit is contained in:
Thomas Gleixner
2018-11-25 19:33:45 +01:00
parent 495d470e98
commit fa1202ef22
3 changed files with 156 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -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)