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Subject[PATCH 01/17] x86/microcode: Untangle from BLK_DEV_INITRD
Date
From: Borislav Petkov <bp@suse.de>

Thomas Voegtle reported that doing oldconfig with a .config which has
CONFIG_MICROCODE enabled but BLK_DEV_INITRD disabled prevents the
microcode loading mechanism from being built.

So untangle it from the BLK_DEV_INITRD dependency so that oldconfig
doesn't turn it off and add an explanatory text to its Kconfig help what
the supported methods for supplying microcode are.

Reported-by: Thomas Voegtle <tv@lio96.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 4.4
---
arch/x86/Kconfig | 27 ++++++++++++++-------------
arch/x86/include/asm/microcode.h | 26 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/microcode/intel.c | 14 ++++----------
3 files changed, 44 insertions(+), 23 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9af2e6338400..405b1858134b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1159,22 +1159,23 @@ config MICROCODE
bool "CPU microcode loading support"
default y
depends on CPU_SUP_AMD || CPU_SUP_INTEL
- depends on BLK_DEV_INITRD
select FW_LOADER
---help---
-
If you say Y here, you will be able to update the microcode on
- certain Intel and AMD processors. The Intel support is for the
- IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
- Xeon etc. The AMD support is for families 0x10 and later. You will
- obviously need the actual microcode binary data itself which is not
- shipped with the Linux kernel.
-
- This option selects the general module only, you need to select
- at least one vendor specific module as well.
-
- To compile this driver as a module, choose M here: the module
- will be called microcode.
+ Intel and AMD processors. The Intel support is for the IA32 family,
+ e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
+ AMD support is for families 0x10 and later. You will obviously need
+ the actual microcode binary data itself which is not shipped with
+ the Linux kernel.
+
+ The preferred method to load microcode from a detached initrd is described
+ in Documentation/x86/early-microcode.txt. For that you need to enable
+ CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
+ initrd for microcode blobs.
+
+ In addition, you can build-in the microcode into the kernel. For that you
+ need to enable FIRMWARE_IN_KERNEL and add the vendor-supplied microcode
+ to the CONFIG_EXTRA_FIRMWARE config option.

config MICROCODE_INTEL
bool "Intel microcode loading support"
diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 1e1b07a5a738..9d3a96c4da78 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -3,6 +3,7 @@

#include <asm/cpu.h>
#include <linux/earlycpio.h>
+#include <linux/initrd.h>

#define native_rdmsr(msr, val1, val2) \
do { \
@@ -143,4 +144,29 @@ static inline void reload_early_microcode(void) { }
static inline bool
get_builtin_firmware(struct cpio_data *cd, const char *name) { return false; }
#endif
+
+static inline unsigned long get_initrd_start(void)
+{
+#ifdef CONFIG_BLK_DEV_INITRD
+ return initrd_start;
+#else
+ return 0;
+#endif
+}
+
+static inline unsigned long get_initrd_start_addr(void)
+{
+#ifdef CONFIG_BLK_DEV_INITRD
+#ifdef CONFIG_X86_32
+ unsigned long *initrd_start_p = (unsigned long *)__pa_nodebug(&initrd_start);
+
+ return (unsigned long)__pa_nodebug(*initrd_start_p);
+#else
+ return get_initrd_start();
+#endif
+#else /* CONFIG_BLK_DEV_INITRD */
+ return 0;
+#endif
+}
+
#endif /* _ASM_X86_MICROCODE_H */
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index ee81c544ee0d..044bbbbcbaf1 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -690,7 +690,7 @@ int __init save_microcode_in_initrd_intel(void)
if (count == 0)
return ret;

- copy_initrd_ptrs(mc_saved, mc_saved_in_initrd, initrd_start, count);
+ copy_initrd_ptrs(mc_saved, mc_saved_in_initrd, get_initrd_start(), count);
ret = save_microcode(&mc_saved_data, mc_saved, count);
if (ret)
pr_err("Cannot save microcode patches from initrd.\n");
@@ -748,20 +748,14 @@ void load_ucode_intel_ap(void)
struct mc_saved_data *mc_saved_data_p;
struct ucode_cpu_info uci;
unsigned long *mc_saved_in_initrd_p;
- unsigned long initrd_start_addr;
enum ucode_state ret;
#ifdef CONFIG_X86_32
- unsigned long *initrd_start_p;

- mc_saved_in_initrd_p =
- (unsigned long *)__pa_nodebug(mc_saved_in_initrd);
+ mc_saved_in_initrd_p = (unsigned long *)__pa_nodebug(mc_saved_in_initrd);
mc_saved_data_p = (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
- initrd_start_p = (unsigned long *)__pa_nodebug(&initrd_start);
- initrd_start_addr = (unsigned long)__pa_nodebug(*initrd_start_p);
#else
- mc_saved_data_p = &mc_saved_data;
mc_saved_in_initrd_p = mc_saved_in_initrd;
- initrd_start_addr = initrd_start;
+ mc_saved_data_p = &mc_saved_data;
#endif

/*
@@ -773,7 +767,7 @@ void load_ucode_intel_ap(void)

collect_cpu_info_early(&uci);
ret = load_microcode(mc_saved_data_p, mc_saved_in_initrd_p,
- initrd_start_addr, &uci);
+ get_initrd_start_addr(), &uci);

if (ret != UCODE_OK)
return;
--
2.3.5
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