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x86/microcode: Untangle from BLK_DEV_INITRD

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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>
Tested-by: Thomas Voegtle <tv@lio96.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 4.4
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1454499225-21544-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov 2016-02-03 12:33:29 +01:00 committed by Ingo Molnar
parent 765bdb406d
commit 5f9c01aa7c
3 changed files with 42 additions and 21 deletions
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23
arch/x86/Kconfig
View File

@ -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.
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.
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.
To compile this driver as a module, choose M here: the module
will be called microcode.
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"

26
arch/x86/include/asm/microcode.h
View File

@ -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 */

14
arch/x86/kernel/cpu/microcode/intel.c
View File

@ -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;