From: Josh Poimboeuf Date: Fri, 12 Apr 2024 18:10:33 +0000 (-0700) Subject: x86/bugs: Fix BHI retpoline check X-Git-Tag: v6.6.29~64 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5facc0428bd2cb2fd3bb7f46d8b862b941a364b3;p=thirdparty%2Fkernel%2Fstable.git x86/bugs: Fix BHI retpoline check [ 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 Signed-off-by: Ingo Molnar Reviewed-by: Pawan Gupta Cc: Borislav Petkov Cc: Linus Torvalds Link: https://lore.kernel.org/r/ad3807424a3953f0323c011a643405619f2a4927.1712944776.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin --- diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 5ff69b1d39b20..c2dc9b7426acb 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";