6.8-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit 69129794d94c544810e68b2b4eaa7e44063f9bf2 ]
Confusingly, X86_FEATURE_RETPOLINE doesn't mean retpolines are enabled, as it also includes the original "AMD retpoline" which isn't a retpoline at all.
Also replace cpu_feature_enabled() with boot_cpu_has() because this is before alternatives are patched and cpu_feature_enabled()'s fallback path is slower than plain old boot_cpu_has().
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: Pawan Gupta pawan.kumar.gupta@linux.intel.com Cc: Borislav Petkov bp@alien8.de Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/ad3807424a3953f0323c011a643405619f2a4927.171294477... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/cpu/bugs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index cbc8c88144e47..e7ceee008bd09 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1651,7 +1651,8 @@ static void __init bhi_select_mitigation(void) return;
/* Retpoline mitigates against BHI unless the CPU has RRSBA behavior */ - if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) { + if (boot_cpu_has(X86_FEATURE_RETPOLINE) && + !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) { spec_ctrl_disable_kernel_rrsba(); if (rrsba_disabled) return; @@ -2803,11 +2804,13 @@ static const char *spectre_bhi_state(void) { if (!boot_cpu_has_bug(X86_BUG_BHI)) return "; BHI: Not affected"; - else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW)) + else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW)) return "; BHI: BHI_DIS_S"; - else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP)) + else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP)) return "; BHI: SW loop, KVM: SW loop"; - else if (boot_cpu_has(X86_FEATURE_RETPOLINE) && rrsba_disabled) + else if (boot_cpu_has(X86_FEATURE_RETPOLINE) && + !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE) && + rrsba_disabled) return "; BHI: Retpoline"; else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT)) return "; BHI: Vulnerable, KVM: SW loop";