5.15-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@kernel.org
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/8c84f7451bfe0dd08543c6082a383f390d4aa7e2.171281347... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/hw-vuln/spectre.rst | 15 ++++++++------- Documentation/admin-guide/kernel-parameters.txt | 12 +++++++----- 2 files changed, 15 insertions(+), 12 deletions(-)
--- 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 @@ -716,13 +716,14 @@ For user space mitigation: 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
--- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3093,6 +3093,7 @@ 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] ssbd=force-off [ARM64] tsx_async_abort=off [X86] @@ -5410,11 +5411,12 @@ 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.