From de6f0921ba49f5e07f57eb227dcb69ebb4776911 Mon Sep 17 00:00:00 2001 From: David Kaplan Date: Mon, 7 Jul 2025 13:33:02 -0500 Subject: [PATCH] x86/bugs: Add attack vector controls for MMIO Use attack vectors controls to determine if MMIO mitigation is required. Signed-off-by: David Kaplan Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250707183316.1349127-8-david.kaplan@amd.com --- arch/x86/kernel/cpu/bugs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 438c482d4bb09..39ff556f35c11 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -639,8 +639,12 @@ static void __init mmio_select_mitigation(void) } /* Microcode will be checked in mmio_update_mitigation(). */ - if (mmio_mitigation == MMIO_MITIGATION_AUTO) - mmio_mitigation = MMIO_MITIGATION_VERW; + if (mmio_mitigation == MMIO_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_MMIO_STALE_DATA)) + mmio_mitigation = MMIO_MITIGATION_VERW; + else + mmio_mitigation = MMIO_MITIGATION_OFF; + } if (mmio_mitigation == MMIO_MITIGATION_OFF) return; @@ -655,7 +659,7 @@ static void __init mmio_select_mitigation(void) static void __init mmio_update_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) || cpu_mitigations_off()) + if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) return; if (verw_clear_cpu_buf_mitigation_selected) @@ -703,7 +707,7 @@ static void __init mmio_apply_mitigation(void) if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) static_branch_enable(&cpu_buf_idle_clear); - if (mmio_nosmt || cpu_mitigations_auto_nosmt()) + if (mmio_nosmt || smt_mitigations == SMT_MITIGATIONS_ON) cpu_smt_disable(false); } -- 2.47.3