This is a note to let you know that I've just added the patch titled
x86/cpu/amd: Add a Zenbleed fix
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-cpu-amd-add-a-zenbleed-fix.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b2d362e150f1a48e95b4224e6ad860948f48c158 Mon Sep 17 00:00:00 2001
From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>
Date: Sat, 15 Jul 2023 13:41:28 +0200
Subject: x86/cpu/amd: Add a Zenbleed fix
From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>
Upstream commit: 522b1d69219d8f083173819fde04f994aa051a98
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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/microcode.h | 1
arch/x86/include/asm/microcode_amd.h | 2 +
arch/x86/include/asm/msr-index.h | 1
arch/x86/kernel/cpu/amd.c | 60 +++++++++++++++++++++++++++++++++++
arch/x86/kernel/cpu/common.c | 2 +
5 files changed, 66 insertions(+)
--- 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;
--- 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(un
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 */
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -407,6 +407,7 @@
#define MSR_AMD64_DE_CFG 0xc0011029
#define MSR_AMD64_DE_CFG_LFENCE_SERIALIZE_BIT 1
#define MSR_AMD64_DE_CFG_LFENCE_SERIALIZE BIT_ULL(MSR_AMD64_DE_CFG_LFENCE_SERIALIZE_BIT)
+#define MSR_AMD64_DE_CFG_ZEN2_FP_BACKUP_FIX_BIT 9
#define MSR_AMD64_BU_CFG2 0xc001102a
#define MSR_AMD64_IBSFETCHCTL 0xc0011030
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -66,6 +66,11 @@ 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++;
@@ -971,6 +976,47 @@ static void init_amd_zn(struct cpuinfo_x
}
}
+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);
@@ -1073,6 +1119,8 @@ static void init_amd(struct cpuinfo_x86
msr_set_bit(MSR_K7_HWCR, MSR_K7_HWCR_IRPERF_EN_BIT);
check_null_seg_clears_base(c);
+
+ zenbleed_check(c);
}
#ifdef CONFIG_X86_32
@@ -1186,3 +1234,15 @@ void set_dr_addr_mask(unsigned long mask
break;
}
}
+
+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);
+}
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2077,6 +2077,8 @@ void microcode_check(void)
perf_check_microcode();
+ amd_check_microcode();
+
/* Reload CPUID max function as it might've changed. */
info.cpuid_level = cpuid_eax(0);
Patches currently in stable-queue which might be from bp@xxxxxxxxx are
queue-4.19/x86-cpu-amd-add-a-zenbleed-fix.patch
queue-4.19/x86-microcode-amd-load-late-on-both-threads-too.patch
queue-4.19/x86-cpu-amd-move-the-errata-checking-functionality-up.patch
queue-4.19/x86-smp-use-dedicated-cache-line-for-mwait_play_dead.patch
