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| author | Pawan Gupta <pawan.kumar.gupta@linux.intel.com> | 2024-03-11 16:57:05 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-04-08 19:27:05 +0200 |
| commit | ec9404e40e8f36421a2b66ecb76dc2209fe7f3ef (patch) | |
| tree | cd708b3c092d7c6809a516cde3f3719c4d8aca06 /arch/x86/Kconfig | |
| parent | x86/bhi: Enumerate Branch History Injection (BHI) bug (diff) | |
| download | linux-ec9404e40e8f36421a2b66ecb76dc2209fe7f3ef.tar.xz linux-ec9404e40e8f36421a2b66ecb76dc2209fe7f3ef.zip | |
x86/bhi: Add BHI mitigation knob
Branch history clearing software sequences and hardware control
BHI_DIS_S were defined to mitigate Branch History Injection (BHI).
Add cmdline spectre_bhi={on|off|auto} to control BHI mitigation:
auto - Deploy the hardware mitigation BHI_DIS_S, if available.
on - Deploy the hardware mitigation BHI_DIS_S, if available,
otherwise deploy the software sequence at syscall entry and
VMexit.
off - Turn off BHI mitigation.
The default is auto mode which does not deploy the software sequence
mitigation. This is because of the hardening done in the syscall
dispatch path, which is the likely target of BHI.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Diffstat (limited to 'arch/x86/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 4fff6ed46e90..29a7b69a1316 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2633,6 +2633,31 @@ config MITIGATION_RFDS stored in floating point, vector and integer registers. See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> +choice + prompt "Clear branch history" + depends on CPU_SUP_INTEL + default SPECTRE_BHI_AUTO + help + Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks + where the branch history buffer is poisoned to speculatively steer + indirect branches. + See <file:Documentation/admin-guide/hw-vuln/spectre.rst> + +config SPECTRE_BHI_ON + bool "on" + help + Equivalent to setting spectre_bhi=on command line parameter. +config SPECTRE_BHI_OFF + bool "off" + help + Equivalent to setting spectre_bhi=off command line parameter. +config SPECTRE_BHI_AUTO + bool "auto" + help + Equivalent to setting spectre_bhi=auto command line parameter. + +endchoice + endif config ARCH_HAS_ADD_PAGES |