diff options
| author | Pawan Gupta <pawan.kumar.gupta@linux.intel.com> | 2019-10-23 11:01:53 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-16 10:27:50 +0100 |
| commit | ab7b39b99f030a15f4f398ea6c2fbe9600e4818c (patch) | |
| tree | 0076e30323bf74e8ad600eb0afd1b583f0e72ed8 /Documentation | |
| parent | 725afc0d60cf8b9e3bf023920c881f4a4261dc49 (diff) | |
x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default
commit 95c5824f75f3ba4c9e8e5a4b1a623c95390ac266 upstream.
Add a kernel cmdline parameter "tsx" to control the Transactional
Synchronization Extensions (TSX) feature. On CPUs that support TSX
control, use "tsx=on|off" to enable or disable TSX. Not specifying this
option is equivalent to "tsx=off". This is because on certain processors
TSX may be used as a part of a speculative side channel attack.
Carve out the TSX controlling functionality into a separate compilation
unit because TSX is a CPU feature while the TSX async abort control
machinery will go to cpu/bugs.c.
[ bp: - Massage, shorten and clear the arg buffer.
- Clarifications of the tsx= possible options - Josh.
- Expand on TSX_CTRL availability - Pawan. ]
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
[bwh: Backported to 4.4:
- Drop __ro_after_init attribute
- Adjust filenames, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 5b94c0bfba85..58421b7f62b0 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -4052,6 +4052,32 @@ bytes respectively. Such letter suffixes can also be entirely omitted. platforms where RDTSC is slow and this accounting can add overhead. + tsx= [X86] Control Transactional Synchronization + Extensions (TSX) feature in Intel processors that + support TSX control. + + This parameter controls the TSX feature. The options are: + + on - Enable TSX on the system. Although there are + mitigations for all known security vulnerabilities, + TSX has been known to be an accelerator for + several previous speculation-related CVEs, and + so there may be unknown security risks associated + with leaving it enabled. + + off - Disable TSX on the system. (Note that this + option takes effect only on newer CPUs which are + not vulnerable to MDS, i.e., have + MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get + the new IA32_TSX_CTRL MSR through a microcode + update. This new MSR allows for the reliable + deactivation of the TSX functionality.) + + Not specifying this option is equivalent to tsx=off. + + See Documentation/hw-vuln/tsx_async_abort.rst + for more details. + turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface Format: |