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    Subject[PATCH] x86/microcode/intel: Quieten down microcode updates on large systems
    Date
    From: Andi Kleen <ak@linux.intel.com>

    On large systems the microcode driver is very noisy, because it prints
    a line for each CPU. The lines are redundant because because usually
    all CPUs are updated to the same microcode revision.

    All other subsystems have been patched previously to not print
    a line for each CPU. Only the microcode driver is left.

    Only print an microcode revision update when something changed. This results
    in typically only a single line being printed.

    v2: Change message to "One or more CPUs"
    Signed-off-by: Andi Kleen <ak@linux.intel.com>
    ---
    arch/x86/kernel/cpu/microcode/intel.c | 25 ++++++++++++++++++-------
    1 file changed, 18 insertions(+), 7 deletions(-)

    diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
    index cbb3cf0..54f5f6c 100644
    --- a/arch/x86/kernel/cpu/microcode/intel.c
    +++ b/arch/x86/kernel/cpu/microcode/intel.c
    @@ -794,6 +794,7 @@ void reload_ucode_intel(void)

    static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
    {
    + static struct cpu_signature prev;
    struct cpuinfo_x86 *c = &cpu_data(cpu_num);
    unsigned int val[2];

    @@ -808,8 +809,14 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
    }

    csig->rev = c->microcode;
    - pr_info("CPU%d sig=0x%x, pf=0x%x, revision=0x%x\n",
    - cpu_num, csig->sig, csig->pf, csig->rev);
    +
    + /* No extra locking on prev, races are harmless. */
    + if (csig->sig != prev.sig || csig->pf != prev.pf ||
    + csig->rev != prev.rev) {
    + pr_info("One or more CPUs sig=0x%x, pf=0x%x, revision=0x%x\n",
    + csig->sig, csig->pf, csig->rev);
    + prev = *csig;
    + }

    return 0;
    }
    @@ -838,6 +845,7 @@ static int apply_microcode_intel(int cpu)
    struct ucode_cpu_info *uci;
    struct cpuinfo_x86 *c;
    unsigned int val[2];
    + static int prev_rev;

    /* We should bind the task to the CPU */
    if (WARN_ON(raw_smp_processor_id() != cpu))
    @@ -872,11 +880,14 @@ static int apply_microcode_intel(int cpu)
    return -1;
    }

    - pr_info("CPU%d updated to revision 0x%x, date = %04x-%02x-%02x\n",
    - cpu, val[1],
    - mc->hdr.date & 0xffff,
    - mc->hdr.date >> 24,
    - (mc->hdr.date >> 16) & 0xff);
    + if (val[1] != prev_rev) {
    + pr_info("One or more CPUs updated to revision 0x%x, date = %04x-%02x-%02x\n",
    + val[1],
    + mc->hdr.date & 0xffff,
    + mc->hdr.date >> 24,
    + (mc->hdr.date >> 16) & 0xff);
    + prev_rev = val[1];
    + }

    c = &cpu_data(cpu);

    --
    2.8.3
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