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Message-ID: <20241105215455.359471-30-david.kaplan@amd.com>
Date: Tue, 5 Nov 2024 15:54:49 -0600
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>
Subject: [PATCH v2 29/35] x86/bugs: Add attack vector controls for retbleed
Use attack vector controls to determine if retbleed mitigation is
required.
Disable SMT if cross-thread protection is desired and STIBP is not
available.
Signed-off-by: David Kaplan <david.kaplan@....com>
---
arch/x86/kernel/cpu/bugs.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index f63fa8a3b9ee..545151114947 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1267,13 +1267,17 @@ static void __init retbleed_select_mitigation(void)
}
if (retbleed_mitigation == RETBLEED_MITIGATION_AUTO) {
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
- boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
- if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY))
- retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
- else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY) &&
- boot_cpu_has(X86_FEATURE_IBPB))
- retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
+ if (should_mitigate_vuln(X86_BUG_RETBLEED)) {
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
+ boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
+ if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY))
+ retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
+ else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY) &&
+ boot_cpu_has(X86_FEATURE_IBPB))
+ retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
+ }
+ } else {
+ retbleed_mitigation = RETBLEED_MITIGATION_NONE;
}
}
}
@@ -1372,7 +1376,8 @@ static void __init retbleed_apply_mitigation(void)
}
if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) &&
- (retbleed_nosmt || cpu_mitigations_auto_nosmt()))
+ (retbleed_nosmt || cpu_mitigations_auto_nosmt() ||
+ cpu_mitigate_attack_vector(CPU_MITIGATE_CROSS_THREAD)))
cpu_smt_disable(false);
}
--
2.34.1
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