From e2a9c03192f54bb53a5422bf5106bdc4d04a7426 Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Wed, 11 Jun 2025 10:30:18 -0700 Subject: [PATCH] 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 --- arch/x86/kernel/cpu/bugs.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 387610ad222d..31f3db0a514e 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; } } -- 2.25.1