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    Subject[PATCH 4.11 132/150] x86/microcode/intel: Clear patch pointer before jettisoning the initrd
    Date
    4.11-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dominik Brodowski <linux@dominikbrodowski.net>

    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.

    Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
    [ Edit and massage commit message. ]
    Signed-off-by: Borislav Petkov <bp@suse.de>
    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/20170607095819.9754-1-bp@alien8.de
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- 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_inte

    show_saved_mc();

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


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