Patch "x86/microcode/intel: Clear patch pointer before jettisoning the initrd" has been added to the 4.11-stable tree

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

x86/microcode/intel: Clear patch pointer before jettisoning the initrd

to the 4.11-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-intel-clear-patch-pointer-before-jettisoning-the-initrd.patch
and it can be found in the queue-4.11 subdirectory.

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

From: Dominik Brodowski <[email protected]>
Date: Wed, 7 Jun 2017 11:58:19 +0200
Subject: x86/microcode/intel: Clear patch pointer before jettisoning the initrd

From: Dominik Brodowski <[email protected]>

commit 5b0bc9ac2ce4881ee318a21f31140584ce4dbdad upstream.

During early boot, load_ucode_intel_ap() uses __load_ucode_intel() to obtain a pointer to the relevant microcode patch (embedded in the initrd), and stores this value in 'intel_ucode_patch' to speed up the microcode patch application for subsequent CPUs.

On resuming from suspend-to-RAM, however, load_ucode_ap() calls load_ucode_intel_ap() for each non-boot-CPU. By then the initramfs is long gone so the pointer stored in 'intel_ucode_patch' no longer points to a valid microcode patch.

Clear that pointer so that we effectively fall back to the CPU hotplug notifier callbacks to update the microcode.

---
 arch/x86/kernel/cpu/microcode/intel.c |    3 +++
 1 file changed, 3 insertions(+)

@@ -619,6 +619,9 @@ int __init save_microcode_in_initrd_inte
 
 	show_saved_mc();
 
+	/* initrd is going away, clear patch ptr. */
+	intel_ucode_patch = NULL;
+
 	return 0;
 }
 

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

queue-4.11/x86-microcode-intel-clear-patch-pointer-before-jettisoning-the-initrd.patch