Messages in this thread Patch in this message | | | From | Josh Poimboeuf <> | Subject | [PATCH v5 2/3] x86/bugs: Remove duplicate Spectre cmdline option descriptions | Date | Mon, 6 May 2024 22:30:05 -0700 |
| |
Duplicating the documentation of all the Spectre kernel cmdline options in two separate files is unwieldy and error-prone. Instead just add a reference to kernel-parameters.txt from spectre.rst.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> --- Documentation/admin-guide/hw-vuln/spectre.rst | 84 ++----------------- 1 file changed, 9 insertions(+), 75 deletions(-)
diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst index 25a04cda4c2c..f9797ab6b38f 100644 --- a/Documentation/admin-guide/hw-vuln/spectre.rst +++ b/Documentation/admin-guide/hw-vuln/spectre.rst @@ -592,85 +592,19 @@ Spectre variant 2 Mitigation control on the kernel command line --------------------------------------------- -Spectre variant 2 mitigation can be disabled or force enabled at the -kernel command line. +In general the kernel selects reasonable default mitigations for the +current CPU. + +Spectre default mitigations can be disabled or changed at the kernel +command line with the following options: nospectre_v1 - - [X86,PPC] Disable mitigations for Spectre Variant 1 - (bounds check bypass). With this option data leaks are - possible in the system. - nospectre_v2 + spectre_v2={option} + spectre_v2_user={option} + spectre_bhi={option} - [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. - - - 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, implies - spectre_v2_user=on - off - unconditionally disable, implies - spectre_v2_user=off - 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_MITIGATION_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 auto pick between generic,lfence - retpoline,generic Retpolines - retpoline,lfence LFENCE; indirect branch - retpoline,amd alias for retpoline,lfence - eibrs Enhanced/Auto IBRS - eibrs,retpoline Enhanced/Auto IBRS + Retpolines - eibrs,lfence Enhanced/Auto IBRS + LFENCE - ibrs use IBRS to protect kernel - - Not specifying this option is equivalent to - spectre_v2=auto. - - In general the kernel by default selects - reasonable mitigations for the current CPU. To - disable Spectre variant 2 mitigations, boot with - spectre_v2=off. Spectre variant 1 mitigations - cannot be disabled. - - spectre_bhi= - - [X86] Control mitigation of Branch History Injection - (BHI) vulnerability. This setting affects the deployment - of the HW BHI control and the SW BHB clearing sequence. - - on - (default) Enable the HW or SW mitigation as - needed. - off - Disable the mitigation. - -For spectre_v2_user see Documentation/admin-guide/kernel-parameters.txt +For more details on the available options, refer to Documentation/admin-guide/kernel-parameters.txt Mitigation selection guide -------------------------- -- 2.44.0
| |