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Message-ID: <20250310164023.779191-24-david.kaplan@amd.com>
Date: Mon, 10 Mar 2025 11:40:10 -0500
From: David Kaplan <david.kaplan@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar
<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>
CC: <linux-kernel@...r.kernel.org>, Brendan Jackman <jackmanb@...gle.com>,
Derek Manwaring <derekmn@...zon.com>
Subject: [PATCH v4 23/36] x86/bugs: Add attack vector controls for mmio
Use attack vectors controls to determine if mmio mitigation is required.
Signed-off-by: David Kaplan <david.kaplan@....com>
---
arch/x86/kernel/cpu/bugs.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 56d3bf343d1f..ba7c2a1ea98f 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -595,15 +595,21 @@ static const char * const mmio_strings[] = {
static void __init mmio_select_mitigation(void)
{
if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
- boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) ||
- cpu_mitigations_off()) {
+ boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN)) {
mmio_mitigation = MMIO_MITIGATION_OFF;
return;
}
/* 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;
/*
* Enable CPU buffer clear mitigation for host and VMM, if also affected
@@ -615,7 +621,7 @@ 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_mitigation_selected)
@@ -665,7 +671,7 @@ static void __init mmio_apply_mitigation(void)
if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO))
static_branch_enable(&mds_idle_clear);
- if (mmio_nosmt || cpu_mitigations_auto_nosmt())
+ if (mmio_nosmt || smt_mitigations == SMT_MITIGATIONS_ON)
cpu_smt_disable(false);
}
--
2.34.1
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