x86/microcode: Fix loading precedence

So it can happen that even with builtin microcode,
CONFIG_BLK_DEV_INITRD=y gets forgotten enabled.

Or, even with that disabled, an initrd image gets supplied by the boot
loader, by omission or is simply forgotten there. And since we do look
at boot_params.hdr.ramdisk_* to know whether we have received an initrd,
we might get puzzled.

So let's just make the loader look for builtin microcode first and if
found, ignore the ramdisk image.

If no builtin found, it falls back to scanning the supplied initrd, of
course.

For that, we move all the initrd scanning in a separate
__scan_microcode_initrd() function and fall back to it only if
load_builtin_intel_microcode() has failed.

Reported-and-tested-by: Gabriel Craciunescu <nix.or.die@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
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/1465225850-7352-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 0 insertions, 24 deletions

diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 9d3a96c4da78..ca2af7ed6cbf 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -145,28 +145,4 @@ 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 */