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Print a warning if any mitigations try to disable SMT at runtime. bugs_smt_disable() is marked __ref because cpu_smt_disable() is an __init function, but it will never be called after init code is free'd. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index fcb1337026f1..6cd7198f7dca 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -455,6 +455,14 @@ static bool __init should_mitigate_vuln(unsigned int b= ug) } } =20 +static void __ref bugs_smt_disable(bool enable) +{ + if (system_state =3D=3D SYSTEM_BOOTING) + cpu_smt_disable(enable); + else + pr_warn("Unable to disable SMT after system boot!\n"); +} + /* Default mitigation for MDS-affected CPUs */ static enum mds_mitigations mds_mitigation __ro_after_init =3D IS_ENABLED(CONFIG_MITIGATION_MDS) ? MDS_MITIGATION_AUTO : MDS_MITIGATION_= OFF; @@ -550,7 +558,7 @@ static void __init mds_apply_mitigation(void) setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) && (mds_nosmt || smt_mitigations =3D=3D SMT_MITIGATIONS_ON)) - cpu_smt_disable(false); + bugs_smt_disable(false); } } =20 @@ -671,7 +679,7 @@ static void __init taa_apply_mitigation(void) setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); =20 if (taa_nosmt || smt_mitigations =3D=3D SMT_MITIGATIONS_ON) - cpu_smt_disable(false); + bugs_smt_disable(false); } } =20 @@ -784,7 +792,7 @@ static void __init mmio_apply_mitigation(void) static_branch_enable(&cpu_buf_idle_clear); =20 if (mmio_nosmt || smt_mitigations =3D=3D SMT_MITIGATIONS_ON) - cpu_smt_disable(false); + bugs_smt_disable(false); } =20 #ifdef CONFIG_DYNAMIC_MITIGATIONS @@ -1592,7 +1600,7 @@ static void __init retbleed_apply_mitigation(void) =20 if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) && (retbleed_nosmt || smt_mitigations =3D=3D SMT_MITIGATIONS_ON)) - cpu_smt_disable(false); + bugs_smt_disable(false); } =20 #ifdef CONFIG_DYNAMIC_MITIGATIONS @@ -3109,10 +3117,10 @@ static void __init l1tf_apply_mitigation(void) break; case L1TF_MITIGATION_FLUSH_NOSMT: case L1TF_MITIGATION_FULL: - cpu_smt_disable(false); + bugs_smt_disable(false); break; case L1TF_MITIGATION_FULL_FORCE: - cpu_smt_disable(true); + bugs_smt_disable(true); break; } =20 --=20 2.34.1