x86/spectre: Add boot time option to select Spectre v2 mitigation

[pandora-kernel.git] / Documentation / kernel-parameters.txt

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1488091..056f77b 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1753,6 +1753,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        register save and restore. The kernel will only save
                        legacy floating-point registers on task switch.
 
+       nospectre_v2    [X86] Disable all mitigations for the Spectre variant 2
+                       (indirect branch prediction) vulnerability. System may
+                       allow data leaks with this option, which is equivalent
+                       to spectre_v2=off.
+
        noxsave         [BUGS=X86] Disables x86 extended register state save
                        and restore using xsave. The kernel will fallback to
                        enabling legacy floating-point and sse state.
@@ -2468,6 +2473,29 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
        specialix=      [HW,SERIAL] Specialix multi-serial port adapter
                        See Documentation/serial/specialix.txt.
 
+       spectre_v2=     [X86] Control mitigation of Spectre variant 2
+                       (indirect branch speculation) vulnerability.
+
+                       on   - unconditionally enable
+                       off  - unconditionally disable
+                       auto - kernel detects whether your CPU model is
+                              vulnerable
+
+                       Selecting 'on' will, and 'auto' may, choose a
+                       mitigation method at run time according to the
+                       CPU, the available microcode, the setting of the
+                       CONFIG_RETPOLINE configuration option, and the
+                       compiler with which the kernel was built.
+
+                       Specific mitigations can also be selected manually:
+
+                       retpoline         - replace indirect branches
+                       retpoline,generic - google's original retpoline
+                       retpoline,amd     - AMD-specific minimal thunk
+
+                       Not specifying this option is equivalent to
+                       spectre_v2=auto.
+
        spia_io_base=   [HW,MTD]
        spia_fio_base=
        spia_pedr=