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Subject[PATCH] x86/microcode/intel: Clear patch pointer before jettisoning the initrd
Date
From: Dominik Brodowski <linux@dominikbrodowski.net>

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 fallback to the CPU hotplug
notifier callbacks to update the microcode.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: <stable@vger.kernel.org> # 4.10..
[ Edit and massage commit message. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/cpu/microcode/intel.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index afdfd237b59f..f522415bf9e5 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -619,6 +619,9 @@ int __init save_microcode_in_initrd_intel(void)

show_saved_mc();

+ /* initrd is going away, clear patch ptr. */
+ intel_ucode_patch = NULL;
+
return 0;
}

--
2.13.0
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