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Message-ID: <168656162970.404.6477920187705031691.tip-bot2@tip-bot2>
Date: Mon, 12 Jun 2023 09:20:29 -0000
From: "tip-bot2 for Borislav Petkov (AMD)" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/microcode] x86/microcode: Add a "microcode=" command line option
The following commit has been merged into the x86/microcode branch of tip:
Commit-ID: 4a7349239418d78193e8d328f5eebd14a3f77bcd
Gitweb: https://git.kernel.org/tip/4a7349239418d78193e8d328f5eebd14a3f77bcd
Author: Borislav Petkov (AMD) <bp@...en8.de>
AuthorDate: Thu, 18 May 2023 03:02:29 +02:00
Committer: Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 12 Jun 2023 11:02:52 +02:00
x86/microcode: Add a "microcode=" command line option
It will be used to control microcode loader behavior. Add the first
chicken bit: to control whether the AMD side should load microcode late
on all logical SMT threads.
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20230605141332.25948-2-bp@alien8.de
---
Documentation/admin-guide/kernel-parameters.txt | 7 +++-
arch/x86/kernel/cpu/microcode/amd.c | 5 +-
arch/x86/kernel/cpu/microcode/core.c | 44 ++++++++++++++++-
arch/x86/kernel/cpu/microcode/internal.h | 16 ++++++-
4 files changed, 71 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/kernel/cpu/microcode/internal.h
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab2..b88ff02 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3228,6 +3228,13 @@
mga= [HW,DRM]
+ microcode= [X86] Control the behavior of the microcode
+ loader. Available options:
+
+ no_late_all - do not load on all SMT threads on
+ AMD. Loading on all logical threads is enabled by
+ default.
+
min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this
physical address is ignored.
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 87208e4..76b5306 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -36,6 +36,8 @@
#include <asm/cpu.h>
#include <asm/msr.h>
+#include "internal.h"
+
static struct equiv_cpu_table {
unsigned int num_entries;
struct equiv_cpu_entry *entry;
@@ -700,7 +702,8 @@ static enum ucode_state apply_microcode_amd(int cpu)
rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);
/* need to apply patch? */
- if (rev > mc_amd->hdr.patch_id) {
+ if ((rev > mc_amd->hdr.patch_id) ||
+ (rev == mc_amd->hdr.patch_id && !(control & LATE_ALL_THREADS))) {
ret = UCODE_OK;
goto out;
}
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 3afcf3d..5f3185d 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -40,11 +40,15 @@
#include <asm/cmdline.h>
#include <asm/setup.h>
+#include "internal.h"
+
#define DRIVER_VERSION "2.2"
static struct microcode_ops *microcode_ops;
static bool dis_ucode_ldr = true;
+unsigned long control = LATE_ALL_THREADS;
+
bool initrd_gone;
LIST_HEAD(microcode_cache);
@@ -522,8 +526,32 @@ static ssize_t processor_flags_show(struct device *dev,
return sprintf(buf, "0x%x\n", uci->cpu_sig.pf);
}
+static ssize_t control_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "0x%lx\n", control);
+}
+
+static ssize_t control_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long val;
+
+ if (kstrtoul(buf, 0, &val) < 0)
+ return -ERANGE;
+
+ if (val & CONTROL_FLAGS_MASK)
+ return -EINVAL;
+
+ control = val;
+
+ return count;
+}
+
static DEVICE_ATTR_RO(version);
static DEVICE_ATTR_RO(processor_flags);
+static DEVICE_ATTR_ADMIN_RW(control);
static struct attribute *mc_default_attrs[] = {
&dev_attr_version.attr,
@@ -622,6 +650,7 @@ static struct attribute *cpu_root_microcode_attrs[] = {
#ifdef CONFIG_MICROCODE_LATE_LOADING
&dev_attr_reload.attr,
#endif
+ &dev_attr_control.attr,
NULL
};
@@ -683,3 +712,18 @@ static int __init microcode_init(void)
}
fs_initcall(save_microcode_in_initrd);
late_initcall(microcode_init);
+
+static int __init parse_cmdline_param(char *str)
+{
+ if (!str)
+ return 0;
+
+ if (*str == '=')
+ str++;
+
+ if (!strcmp(str, "no_late_all"))
+ control &= ~LATE_ALL_THREADS;
+
+ return 1;
+}
+__setup("microcode", parse_cmdline_param);
diff --git a/arch/x86/kernel/cpu/microcode/internal.h b/arch/x86/kernel/cpu/microcode/internal.h
new file mode 100644
index 0000000..5e3c5fc
--- /dev/null
+++ b/arch/x86/kernel/cpu/microcode/internal.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __X86_MICROCODE_INTERNAL_H__
+#define __X86_MICROCODE_INTERNAL_H__
+
+extern unsigned long control;
+
+/* Loader control flags. */
+enum control_flags {
+ __LATE_ALL_THREADS = 0,
+ __CONTROL_FLAGS_NUM,
+};
+
+#define LATE_ALL_THREADS BIT_ULL(__LATE_ALL_THREADS)
+#define CONTROL_FLAGS_MASK ~(BIT_ULL(__CONTROL_FLAGS_NUM) - 1)
+
+#endif /* __X86_MICROCODE_INTERNAL_H__ */
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