linux-kernel - [PATCH 02/13] x86/CPU/AMD: Carve out the erratum 1386 fix

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Message-ID: <20231120104152.13740-3-bp@alien8.de>
Date:   Mon, 20 Nov 2023 11:41:41 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 02/13] x86/CPU/AMD: Carve out the erratum 1386 fix

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

Call it on the affected CPU generations.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 arch/x86/kernel/cpu/amd.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index fa6ba63ca7e2..b3f939101368 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -984,6 +984,19 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
 	clear_rdrand_cpuid_bit(c);
 }
 
+static void fix_erratum_1386(struct cpuinfo_x86 *c)
+{
+	/*
+	 * Work around Erratum 1386.  The XSAVES instruction malfunctions in
+	 * certain circumstances on Zen1/2 uarch, and not all parts have had
+	 * updated microcode at the time of writing (March 2023).
+	 *
+	 * Affected parts all have no supervisor XSAVE states, meaning that
+	 * the XSAVEC instruction (which works fine) is equivalent.
+	 */
+	clear_cpu_cap(c, X86_FEATURE_XSAVES);
+}
+
 void init_spectral_chicken(struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_CPU_UNRET_ENTRY
@@ -1004,15 +1017,6 @@ void init_spectral_chicken(struct cpuinfo_x86 *c)
 		}
 	}
 #endif
-	/*
-	 * Work around Erratum 1386.  The XSAVES instruction malfunctions in
-	 * certain circumstances on Zen1/2 uarch, and not all parts have had
-	 * updated microcode at the time of writing (March 2023).
-	 *
-	 * Affected parts all have no supervisor XSAVE states, meaning that
-	 * the XSAVEC instruction (which works fine) is equivalent.
-	 */
-	clear_cpu_cap(c, X86_FEATURE_XSAVES);
 }
 
 static void init_amd_zn(struct cpuinfo_x86 *c)
@@ -1040,10 +1044,12 @@ static void init_amd_zn(struct cpuinfo_x86 *c)
 
 static void init_amd_zen(struct cpuinfo_x86 *c)
 {
+	fix_erratum_1386(c);
 }
 
 static void init_amd_zen2(struct cpuinfo_x86 *c)
 {
+	fix_erratum_1386(c);
 }
 
 static void init_amd_zen3(struct cpuinfo_x86 *c)
-- 
2.42.0.rc0.25.ga82fb66fed25