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    Subject[PATCH 05/22] x86/srso: Fix SBPB enablement for mitigations=off
    Date
    If the user has requested no mitigations with mitigations=off, use the
    lighter-weight SBPB instead of IBPB for other mitigations.

    Note that even with mitigations=off, IBPB/SBPB may still be used for
    Spectre v2 user <-> user protection. Whether that makes sense is a
    question for another day.

    Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
    Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
    ---
    arch/x86/kernel/cpu/bugs.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
    index 10499bcd4e39..ff5bfe8f0ee9 100644
    --- a/arch/x86/kernel/cpu/bugs.c
    +++ b/arch/x86/kernel/cpu/bugs.c
    @@ -2496,8 +2496,7 @@ static void __init srso_select_mitigation(void)
    pr_info("%s%s\n", srso_strings[srso_mitigation], (has_microcode ? "" : ", no microcode"));

    pred_cmd:
    - if ((boot_cpu_has(X86_FEATURE_SRSO_NO) || srso_cmd == SRSO_CMD_OFF) &&
    - boot_cpu_has(X86_FEATURE_SBPB))
    + if (boot_cpu_has(X86_FEATURE_SBPB) && srso_mitigation == SRSO_MITIGATION_NONE)
    x86_pred_cmd = PRED_CMD_SBPB;
    }

    --
    2.41.0
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