diff --git a/arch/x86/include/asm/cmdline.h b/arch/x86/include/asm/cmdline.h
new file mode 100644
index 0000000000000000000000000000000000000000..e01f7f7ccb0c5711db4f1fe130938cee36169965
--- /dev/null
+++ b/arch/x86/include/asm/cmdline.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_X86_CMDLINE_H
+#define _ASM_X86_CMDLINE_H
+
+int cmdline_find_option_bool(const char *cmdline_ptr, const char *option);
+
+#endif /* _ASM_X86_CMDLINE_H */
diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index b59827e765292459247baa6866329ddec3e7fa91..64dc362506b789ca3ea9986669e111da2d9ccea8 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -25,6 +25,7 @@ struct cpu_signature {
struct device;
enum ucode_state { UCODE_ERROR, UCODE_OK, UCODE_NFOUND };
+extern bool dis_ucode_ldr;
struct microcode_ops {
enum ucode_state (*request_microcode_user) (int cpu,
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 15c987698b0f730ed47b3f0daaf1021e6b1abdff..dd9d6190b08dfae5fdaee714ab5f556040af516e 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -97,6 +97,9 @@ MODULE_LICENSE("GPL");
static struct microcode_ops *microcode_ops;
+bool dis_ucode_ldr;
+module_param(dis_ucode_ldr, bool, 0);
+
/*
* Synchronization.
*
@@ -546,6 +549,9 @@ static int __init microcode_init(void)
struct cpuinfo_x86 *c = &cpu_data(0);
int error;
+ if (dis_ucode_ldr)
+ return 0;
+
if (c->x86_vendor == X86_VENDOR_INTEL)
microcode_ops = init_intel_microcode();
else if (c->x86_vendor == X86_VENDOR_AMD)
diff --git a/arch/x86/kernel/cpu/microcode/core_early.c b/arch/x86/kernel/cpu/microcode/core_early.c
index be7f8514f57752f0414094e6649f258ffbbc063c..5f28a64e71ea9e834bb835ed5fe4d8e7adaf472f 100644
--- a/arch/x86/kernel/cpu/microcode/core_early.c
+++ b/arch/x86/kernel/cpu/microcode/core_early.c
@@ -17,9 +17,11 @@
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
+#include <asm/microcode.h>
#include <asm/microcode_intel.h>
#include <asm/microcode_amd.h>
#include <asm/processor.h>
+#include <asm/cmdline.h>
#define QCHAR(a, b, c, d) ((a) + ((b) << 8) + ((c) << 16) + ((d) << 24))
#define CPUID_INTEL1 QCHAR('G', 'e', 'n', 'u')
@@ -72,10 +74,33 @@ static int x86_family(void)
return x86;
}
+static bool __init check_loader_disabled_bsp(void)
+{
+#ifdef CONFIG_X86_32
+ const char *cmdline = (const char *)__pa_nodebug(boot_command_line);
+ const char *opt = "dis_ucode_ldr";
+ const char *option = (const char *)__pa_nodebug(opt);
+ bool *res = (bool *)__pa_nodebug(&dis_ucode_ldr);
+
+#else /* CONFIG_X86_64 */
+ const char *cmdline = boot_command_line;
+ const char *option = "dis_ucode_ldr";
+ bool *res = &dis_ucode_ldr;
+#endif
+
+ if (cmdline_find_option_bool(cmdline, option))
+ *res = true;
+
+ return *res;
+}
+
void __init load_ucode_bsp(void)
{
int vendor, x86;
+ if (check_loader_disabled_bsp())
+ return;
+
if (!have_cpuid_p())
return;
@@ -96,10 +121,22 @@ void __init load_ucode_bsp(void)
}
}
+static bool check_loader_disabled_ap(void)
+{
+#ifdef CONFIG_X86_32
+ return __pa_nodebug(dis_ucode_ldr);
+#else
+ return dis_ucode_ldr;
+#endif
+}
+
void load_ucode_ap(void)
{
int vendor, x86;
+ if (check_loader_disabled_ap())
+ return;
+
if (!have_cpuid_p())
return;
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index eabcb6e6a9001d22d8af24cbad00780be6e734d2..4d4f96a27638c2bbeedf6a4206518508180d971e 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -16,7 +16,7 @@ clean-files := inat-tables.c
obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
-lib-y := delay.o misc.o
+lib-y := delay.o misc.o cmdline.o
lib-y += thunk_$(BITS).o
lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
lib-y += memcpy_$(BITS).o
diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
new file mode 100644
index 0000000000000000000000000000000000000000..422db000d72767adf718dc75db682e5df576e877
--- /dev/null
+++ b/arch/x86/lib/cmdline.c
@@ -0,0 +1,84 @@
+/*
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ *
+ * Misc librarized functions for cmdline poking.
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <asm/setup.h>
+
+static inline int myisspace(u8 c)
+{
+ return c <= ' '; /* Close enough approximation */
+}
+
+/**
+ * Find a boolean option (like quiet,noapic,nosmp....)
+ *
+ * @cmdline: the cmdline string
+ * @option: option string to look for
+ *
+ * Returns the position of that @option (starts counting with 1)
+ * or 0 on not found.
+ */
+int cmdline_find_option_bool(const char *cmdline, const char *option)
+{
+ char c;
+ int len, pos = 0, wstart = 0;
+ const char *opptr = NULL;
+ enum {
+ st_wordstart = 0, /* Start of word/after whitespace */
+ st_wordcmp, /* Comparing this word */
+ st_wordskip, /* Miscompare, skip */
+ } state = st_wordstart;
+
+ if (!cmdline)
+ return -1; /* No command line */
+
+ len = min_t(int, strlen(cmdline), COMMAND_LINE_SIZE);
+ if (!len)
+ return 0;
+
+ while (len--) {
+ c = *(char *)cmdline++;
+ pos++;
+
+ switch (state) {
+ case st_wordstart:
+ if (!c)
+ return 0;
+ else if (myisspace(c))
+ break;
+
+ state = st_wordcmp;
+ opptr = option;
+ wstart = pos;
+ /* fall through */
+
+ case st_wordcmp:
+ if (!*opptr)
+ if (!c || myisspace(c))
+ return wstart;
+ else
+ state = st_wordskip;
+ else if (!c)
+ return 0;
+ else if (c != *opptr++)
+ state = st_wordskip;
+ else if (!len) /* last word and is matching */
+ return wstart;
+ break;
+
+ case st_wordskip:
+ if (!c)
+ return 0;
+ else if (myisspace(c))
+ state = st_wordstart;
+ break;
+ }
+ }
+
+ return 0; /* Buffer overrun */
+}