Patch "x86/microcode: Fix suspend to RAM with builtin microcode" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

x86/microcode: Fix suspend to RAM with builtin microcode

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-microcode-fix-suspend-to-ram-with-builtin-microcode.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Borislav Petkov <[email protected]>
Date: Mon, 6 Jun 2016 17:10:43 +0200
Subject: x86/microcode: Fix suspend to RAM with builtin microcode

From: Borislav Petkov <[email protected]>

commit 4b703305d98bf7350d4b2953ee39a3aa2eeb1778 upstream.

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.

---
 arch/x86/include/asm/microcode.h     |    2 --
 arch/x86/kernel/cpu/microcode/core.c |    3 ++-
 arch/x86/mm/init.c                   |    7 -------
 3 files changed, 2 insertions(+), 10 deletions(-)

@@ -133,13 +133,11 @@ static inline unsigned int x86_cpuid_fam
 #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; }

@@ -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);

@@ -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

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/x86-microcode-fix-suspend-to-ram-with-builtin-microcode.patch