kernel/SOURCES/1049-x86-cpu-amd-Add-a-Zenbleed-fix.patch

From 661c6baa7f0dd4ef365c1cfd5aee9e999304fab2 Mon Sep 17 00:00:00 2001
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Date: Sat, 15 Jul 2023 13:41:28 +0200
Subject: [PATCH 35/36] x86/cpu/amd: Add a Zenbleed fix

Add a fix for the Zen2 VZEROUPPER data corruption bug where under
certain circumstances executing VZEROUPPER can cause register
corruption or leak data.

The optimal fix is through microcode but in the case the proper
microcode revision has not been applied, enable a fallback fix using
a chicken bit.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
(cherry picked from commit 522b1d69219d8f083173819fde04f994aa051a98)

CVE: CVE-2023-20593
Signed-off-by: Mridula Shastry <mridula.c.shastry@oracle.com>
Reviewed-by: Todd Vierling <todd.vierling@oracle.com>
---
 arch/x86/include/asm/microcode.h     |  1 +
 arch/x86/include/asm/microcode_amd.h |  2 +
 arch/x86/include/asm/msr-index.h     |  2 +
 arch/x86/kernel/cpu/amd.c            | 60 ++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/common.c         |  2 +
 5 files changed, 67 insertions(+)

diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 629330986955..2e23f658c69b 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -5,6 +5,7 @@
 #include <asm/cpu.h>
 #include <linux/earlycpio.h>
 #include <linux/initrd.h>
+#include <asm/microcode_amd.h>
 
 struct ucode_patch {
 	struct list_head plist;
diff --git a/arch/x86/include/asm/microcode_amd.h b/arch/x86/include/asm/microcode_amd.h
index a645b25ee442..403a8e76b310 100644
--- a/arch/x86/include/asm/microcode_amd.h
+++ b/arch/x86/include/asm/microcode_amd.h
@@ -48,11 +48,13 @@ extern void __init load_ucode_amd_bsp(unsigned int family);
 extern void load_ucode_amd_ap(unsigned int family);
 extern int __init save_microcode_in_initrd_amd(unsigned int family);
 void reload_ucode_amd(unsigned int cpu);
+extern void amd_check_microcode(void);
 #else
 static inline void __init load_ucode_amd_bsp(unsigned int family) {}
 static inline void load_ucode_amd_ap(unsigned int family) {}
 static inline int __init
 save_microcode_in_initrd_amd(unsigned int family) { return -EINVAL; }
 static inline void reload_ucode_amd(unsigned int cpu) {}
+static inline void amd_check_microcode(void) {}
 #endif
 #endif /* _ASM_X86_MICROCODE_AMD_H */
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index bf54eb786776..bc38cbf0ac20 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -498,6 +498,8 @@
 #define MSR_AMD_PPIN			0xc00102f1
 #define MSR_AMD64_LS_CFG		0xc0011020
 #define MSR_AMD64_DC_CFG		0xc0011022
+#define MSR_AMD64_DE_CFG_ZEN2_FP_BACKUP_FIX_BIT 9
+
 #define MSR_AMD64_BU_CFG2		0xc001102a
 #define MSR_AMD64_IBSFETCHCTL		0xc0011030
 #define MSR_AMD64_IBSFETCHLINAD		0xc0011031
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index c2979e3bed04..384e484cbbdc 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -69,6 +69,11 @@ static const int amd_erratum_383[] =
 static const int amd_erratum_1054[] =
 	AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x17, 0, 0, 0x2f, 0xf));
 
+static const int amd_zenbleed[] =
+	AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x17, 0x30, 0x0, 0x4f, 0xf),
+			   AMD_MODEL_RANGE(0x17, 0x60, 0x0, 0x7f, 0xf),
+			   AMD_MODEL_RANGE(0x17, 0xa0, 0x0, 0xaf, 0xf));
+
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum)
 {
 	int osvw_id = *erratum++;
@@ -957,6 +962,47 @@ static void init_amd_zn(struct cpuinfo_x86 *c)
 	}
 }
 
+static bool cpu_has_zenbleed_microcode(void)
+{
+	u32 good_rev = 0;
+
+	switch (boot_cpu_data.x86_model) {
+	case 0x30 ... 0x3f: good_rev = 0x0830107a; break;
+	case 0x60 ... 0x67: good_rev = 0x0860010b; break;
+	case 0x68 ... 0x6f: good_rev = 0x08608105; break;
+	case 0x70 ... 0x7f: good_rev = 0x08701032; break;
+	case 0xa0 ... 0xaf: good_rev = 0x08a00008; break;
+
+	default:
+		return false;
+		break;
+	}
+
+	if (boot_cpu_data.microcode < good_rev)
+		return false;
+
+	return true;
+}
+
+static void zenbleed_check(struct cpuinfo_x86 *c)
+{
+	if (!cpu_has_amd_erratum(c, amd_zenbleed))
+		return;
+
+	if (cpu_has(c, X86_FEATURE_HYPERVISOR))
+		return;
+
+	if (!cpu_has(c, X86_FEATURE_AVX))
+		return;
+
+	if (!cpu_has_zenbleed_microcode()) {
+		pr_notice_once("Zenbleed: please update your microcode for the most optimal fix\n");
+		msr_set_bit(MSR_AMD64_DE_CFG, MSR_AMD64_DE_CFG_ZEN2_FP_BACKUP_FIX_BIT);
+	} else {
+		msr_clear_bit(MSR_AMD64_DE_CFG, MSR_AMD64_DE_CFG_ZEN2_FP_BACKUP_FIX_BIT);
+	}
+}
+
 static void init_amd(struct cpuinfo_x86 *c)
 {
 	early_init_amd(c);
@@ -1057,6 +1103,8 @@ static void init_amd(struct cpuinfo_x86 *c)
 	if (spectre_v2_in_eibrs_mode(spectre_v2_enabled) &&
 	    cpu_has(c, X86_FEATURE_AUTOIBRS))
 		WARN_ON_ONCE(msr_set_bit(MSR_EFER, _EFER_AUTOIBRS));
+
+	zenbleed_check(c);
 }
 
 #ifdef CONFIG_X86_32
@@ -1205,3 +1253,15 @@ u32 amd_get_highest_perf(void)
 	return 255;
 }
 EXPORT_SYMBOL_GPL(amd_get_highest_perf);
+
+static void zenbleed_check_cpu(void *unused)
+{
+	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
+
+	zenbleed_check(c);
+}
+
+void amd_check_microcode(void)
+{
+	on_each_cpu(zenbleed_check_cpu, NULL, 1);
+}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c5c08a3ace2a..61039cf3d6eb 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2187,6 +2187,8 @@ void microcode_check(struct cpuinfo_x86 *prev_info)
 
 	perf_check_microcode();
 
+	amd_check_microcode();
+
 	store_cpu_caps(&curr_info);
 
 	if (!memcmp(&prev_info->x86_capability, &curr_info.x86_capability,
-- 
2.39.3