linux-kernel - [PATCH 05/13] x86/CPU/AMD: Call the spectral chicken in the Zen2 init function

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Message-ID: <20231120104152.13740-6-bp@alien8.de>
Date:   Mon, 20 Nov 2023 11:41:44 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 05/13] x86/CPU/AMD: Call the spectral chicken in the Zen2 init function

From: "Borislav Petkov (AMD)" <bp@...en8.de>

No functional change.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 arch/x86/kernel/cpu/amd.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 6d87c43e4ee9..f43a70d495da 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -1007,10 +1007,8 @@ void init_spectral_chicken(struct cpuinfo_x86 *c)
 	 *
 	 * This suppresses speculation from the middle of a basic block, i.e. it
 	 * suppresses non-branch predictions.
-	 *
-	 * We use STIBP as a heuristic to filter out Zen2 from the rest of F17H
 	 */
-	if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && cpu_has(c, X86_FEATURE_AMD_STIBP)) {
+	if (!cpu_has(c, X86_FEATURE_HYPERVISOR)) {
 		if (!rdmsrl_safe(MSR_ZEN2_SPECTRAL_CHICKEN, &value)) {
 			value |= MSR_ZEN2_SPECTRAL_CHICKEN_BIT;
 			wrmsrl_safe(MSR_ZEN2_SPECTRAL_CHICKEN, value);
@@ -1041,6 +1039,7 @@ static void init_amd_zen(struct cpuinfo_x86 *c)
 
 static void init_amd_zen2(struct cpuinfo_x86 *c)
 {
+	init_spectral_chicken(c);
 	fix_erratum_1386(c);
 }
 
@@ -1136,7 +1135,7 @@ static void init_amd(struct cpuinfo_x86 *c)
 	case 0x12: init_amd_ln(c); break;
 	case 0x15: init_amd_bd(c); break;
 	case 0x16: init_amd_jg(c); break;
-	case 0x17: init_spectral_chicken(c);
+	case 0x17:
 		   fallthrough;
 	case 0x19: init_amd_zn(c); break;
 	}
-- 
2.42.0.rc0.25.ga82fb66fed25