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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by SN1PEPF0002BA50.mail.protection.outlook.com (10.167.242.73) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9228.7 via Frontend Transport; Mon, 13 Oct 2025 14:35:29 +0000 Received: from tiny.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Mon, 13 Oct 2025 07:35:27 -0700 From: David Kaplan To: Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Josh Poimboeuf , Pawan Gupta , Ingo Molnar , Dave Hansen , , "H . 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Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index e765ac0b9240..67561e5c2154 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2360,6 +2360,17 @@ static void __init bhi_apply_mitigation(void) setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_VMEXIT); } =20 +#ifdef CONFIG_DYNAMIC_MITIGATIONS +static void bhi_reset_mitigation(void) +{ + /* RRSBA already cleared in spectre_v2_reset_mitigation() */ + setup_clear_cpu_cap(X86_FEATURE_CLEAR_BHB_VMEXIT); + setup_clear_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP); + bhi_mitigation =3D IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? + BHI_MITIGATION_AUTO : BHI_MITIGATION_OFF; +} +#endif + static void __init spectre_v2_select_mitigation(void) { if ((spectre_v2_cmd =3D=3D SPECTRE_V2_CMD_RETPOLINE || @@ -3954,5 +3965,6 @@ void arch_cpu_reset_mitigations(void) srbds_reset_mitigation(); srso_reset_mitigation(); gds_reset_mitigation(); + bhi_reset_mitigation(); } #endif --=20 2.34.1