On Thu, Nov 12, 2015 at 11:56:12AM +0100, Borislav Petkov wrote:
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c 
> b/arch/x86/kernel/cpu/perf_event_intel_pt.c
> index 42169283448b..fa1262b025e7 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
> @@ -1129,6 +1129,9 @@ static __init int pt_init(void)
>  {
>       int ret, cpu, prior_warn = 0;
>  
> +     if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
> +             return 0;
> +

Does not apply; conflicts with:


commit 73fdeb66592ee80dffb16fb8a9b7378a00c1a826
Author: Huaitong Han <[email protected]>
Date:   Mon Aug 31 16:21:02 2015 +0800

    perf/x86/intel/pt: Fix KVM warning due to doing rdmsr() before the CPUID 
test
    
    If KVM does not support INTEL_PT, guest MSR_IA32_RTIT_CTL reading will
    produce host warning like "kvm [2469]: vcpu0 unhandled rdmsr: 0x570".
    
    Guest can determine whether the CPU supports Intel_PT according to CPUID,
    so test_cpu_cap function is added before rdmsr,and it is more in line with
    the code style.
    
    Signed-off-by: Huaitong Han <[email protected]>
    Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
    Reviewed-by: Alexander Shishkin <[email protected]>
    Cc: Arnaldo Carvalho de Melo <[email protected]>
    Cc: Jiri Olsa <[email protected]>
    Cc: Linus Torvalds <[email protected]>
    Cc: Peter Zijlstra <[email protected]>
    Cc: Stephane Eranian <[email protected]>
    Cc: Thomas Gleixner <[email protected]>
    Cc: Vince Weaver <[email protected]>
    Cc: [email protected]
    Link: 
http://lkml.kernel.org/r/[email protected]
    Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c 
b/arch/x86/kernel/cpu/perf_event_intel_pt.c
index 42169283448b..868e1194337f 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
@@ -139,9 +139,6 @@ static int __init pt_pmu_hw_init(void)
        long i;
 
        attrs = NULL;
-       ret = -ENODEV;
-       if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT))
-               goto fail;
 
        for (i = 0; i < PT_CPUID_LEAVES; i++) {
                cpuid_count(20, i,
@@ -1130,6 +1127,10 @@ static __init int pt_init(void)
        int ret, cpu, prior_warn = 0;
 
        BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE);
+
+       if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT))
+               return -ENODEV;
+
        get_online_cpus();
        for_each_online_cpu(cpu) {
                u64 ctl;
--
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