From: Pawan Gupta Date: Wed, 11 Jun 2025 17:30:18 +0000 (-0700) Subject: x86/bugs: Remove its=stuff dependency on retbleed X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e2a9c03192f54bb53a5422bf5106bdc4d04a7426;p=users%2Fjedix%2Flinux-maple.git x86/bugs: Remove its=stuff dependency on retbleed Allow ITS to enable stuffing independent of retbleed. The dependency is only on retpoline. It is a valid case for retbleed to be mitigated by eIBRS while ITS deploys stuffing at the same time. Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250611-eibrs-fix-v4-6-5ff86cac6c61@linux.intel.com --- diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 387610ad222d4..31f3db0a514ea 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1467,13 +1467,8 @@ static void __init its_update_mitigation(void) break; } - /* - * retbleed_update_mitigation() will try to do stuffing if its=stuff. - * If it can't, such as if spectre_v2!=retpoline, then fall back to - * aligned thunks. - */ if (its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF && - retbleed_mitigation != RETBLEED_MITIGATION_STUFF) + !cdt_possible(spectre_v2_enabled)) its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; pr_info("%s\n", its_strings[its_mitigation]); @@ -1485,8 +1480,6 @@ static void __init its_apply_mitigation(void) case ITS_MITIGATION_OFF: case ITS_MITIGATION_AUTO: case ITS_MITIGATION_VMEXIT_ONLY: - /* its=stuff forces retbleed stuffing and is enabled there. */ - case ITS_MITIGATION_RETPOLINE_STUFF: break; case ITS_MITIGATION_ALIGNED_THUNKS: if (!boot_cpu_has(X86_FEATURE_RETPOLINE)) @@ -1495,6 +1488,11 @@ static void __init its_apply_mitigation(void) setup_force_cpu_cap(X86_FEATURE_RETHUNK); set_return_thunk(its_return_thunk); break; + case ITS_MITIGATION_RETPOLINE_STUFF: + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH); + set_return_thunk(call_depth_return_thunk); + break; } }