x86/microcode: Fix suspend to RAM with builtin microcode

Usually, after we have found the proper microcode blob for the current
machine, we stash it away for later use with save_microcode_in_initrd().

However, with builtin microcode which doesn't come from the initrd, we
don't call that function because CONFIG_BLK_DEV_INITRD=n and even if
set, we don't have a valid initrd.

In order to fix this, let's make save_microcode_in_initrd() an
fs_initcall which runs before rootfs_initcall() as this was the time it
was called previously through:

 rootfs_initcall(populate_rootfs)
 |-> free_initrd()
     |-> free_initrd_mem()
         |-> save_microcode_in_initrd()

Also, we make it run independently from initrd functionality being
present or not.

And since it is called in the microcode loader only now, we can also
make it static.

Reported-and-tested-by: Jim Bos <jim876@xs4all.nl>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # v4.6
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/1465225850-7352-3-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 2 insertions, 10 deletions

diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index ca2af7ed6cbf..da0d81fa0b54 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -133,13 +133,11 @@ static inline unsigned int x86_cpuid_family(void)
 #ifdef CONFIG_MICROCODE
 extern void __init load_ucode_bsp(void);
 extern void load_ucode_ap(void);
-extern int __init save_microcode_in_initrd(void);
 void reload_early_microcode(void);
 extern bool get_builtin_firmware(struct cpio_data *cd, const char *name);
 #else
 static inline void __init load_ucode_bsp(void)                  { }
 static inline void load_ucode_ap(void)                          { }
-static inline int __init save_microcode_in_initrd(void)         { return 0; }
 static inline void reload_early_microcode(void)                 { }
 static inline bool
 get_builtin_firmware(struct cpio_data *cd, const char *name)    { return false; }
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index ac360bfbbdb6..12823b6ebd6d 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -175,7 +175,7 @@ void load_ucode_ap(void)
         }
 }
 
-int __init save_microcode_in_initrd(void)
+static int __init save_microcode_in_initrd(void)
 {
         struct cpuinfo_x86 *c = &boot_cpu_data;
 
@@ -691,4 +691,5 @@ int __init microcode_init(void)
         return error;
 
 }
+fs_initcall(save_microcode_in_initrd);
 late_initcall(microcode_init);
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 372aad2b3291..dffd162db0a4 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -696,13 +696,6 @@ void free_initmem(void)
 void __init free_initrd_mem(unsigned long start, unsigned long end)
 {
         /*
-         * Remember, initrd memory may contain microcode or other useful things.
-         * Before we lose initrd mem, we need to find a place to hold them
-         * now that normal virtual memory is enabled.
-         */
-        save_microcode_in_initrd();
-
-        /*
          * end could be not aligned, and We can not align that,
          * decompresser could be confused by aligned initrd_end
          * We already reserve the end partial page before in