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| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2024-04-11 08:40:45 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-04-17 12:23:40 +0300 |
| commit | 2fa1969f360e16230a7812c89426bee7104679be (patch) | |
| tree | df8dcb39da7418bd4749000a92d9c96e38145da7 /Documentation | |
| parent | 183d8beabff578b0ee764e2332c25c36fe836f08 (diff) | |
| download | linux-2fa1969f360e16230a7812c89426bee7104679be.tar.xz | |
x86/bugs: Fix BHI documentation
commit dfe648903f42296866d79f10d03f8c85c9dfba30 upstream.
Fix up some inaccuracies in the BHI documentation.
Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/8c84f7451bfe0dd08543c6082a383f390d4aa7e2.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/hw-vuln/spectre.rst | 15 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 12 |
2 files changed, 15 insertions, 12 deletions
diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst index 9edb2860a3e1..d4f260634074 100644 --- a/Documentation/admin-guide/hw-vuln/spectre.rst +++ b/Documentation/admin-guide/hw-vuln/spectre.rst @@ -439,11 +439,11 @@ The possible values in this file are: - System is protected by retpoline * - BHI: BHI_DIS_S - System is protected by BHI_DIS_S - * - BHI: SW loop; KVM SW loop + * - BHI: SW loop, KVM SW loop - System is protected by software clearing sequence * - BHI: Syscall hardening - Syscalls are hardened against BHI - * - BHI: Syscall hardening; KVM: SW loop + * - BHI: Syscall hardening, KVM: SW loop - System is protected from userspace attacks by syscall hardening; KVM is protected by software clearing sequence Full mitigation might require a microcode update from the CPU @@ -666,13 +666,14 @@ kernel command line. of the HW BHI control and the SW BHB clearing sequence. on - unconditionally enable. + (default) Enable the HW or SW mitigation as + needed. off - unconditionally disable. + Disable the mitigation. auto - enable if hardware mitigation - control(BHI_DIS_S) is available, otherwise - enable alternate mitigation in KVM. + Enable the HW mitigation if needed, but + *don't* enable the SW mitigation except for KVM. + The system may be vulnerable. For spectre_v2_user see Documentation/admin-guide/kernel-parameters.txt diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 95efaccca453..5d56eccd93d8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3419,6 +3419,7 @@ reg_file_data_sampling=off [X86] retbleed=off [X86] spec_store_bypass_disable=off [X86,PPC] + spectre_bhi=off [X86] spectre_v2_user=off [X86] srbds=off [X86,INTEL] ssbd=force-off [ARM64] @@ -6037,11 +6038,12 @@ deployment of the HW BHI control and the SW BHB clearing sequence. - on - unconditionally enable. - off - unconditionally disable. - auto - (default) enable hardware mitigation - (BHI_DIS_S) if available, otherwise enable - alternate mitigation in KVM. + on - (default) Enable the HW or SW mitigation + as needed. + off - Disable the mitigation. + auto - Enable the HW mitigation if needed, but + *don't* enable the SW mitigation except + for KVM. The system may be vulnerable. spectre_v2= [X86] Control mitigation of Spectre variant 2 (indirect branch speculation) vulnerability. |