Comment 5 for bug 994378

this patch fixed the bug:
commit 338b522ca43cfd32d11a370f4203bcd089c6c877
Author: Kan Liang <email address hidden>
Date: Mon Jul 14 12:25:56 2014 -0700

    perf/x86/intel: Protect LBR and extra_regs against KVM lying

    With -cpu host, KVM reports LBR and extra_regs support, if the host has
    support.

    When the guest perf driver tries to access LBR or extra_regs MSR,
    it #GPs all MSR accesses,since KVM doesn't handle LBR and extra_regs support.
    So check the related MSRs access right once at initialization time to avoid
    the error access at runtime.

    For reproducing the issue, please build the kernel with CONFIG_KVM_INTEL = y
    (for host kernel).
    And CONFIG_PARAVIRT = n and CONFIG_KVM_GUEST = n (for guest kernel).
    Start the guest with -cpu host.
    Run perf record with --branch-any or --branch-filter in guest to trigger LBR
    Run perf stat offcore events (E.g. LLC-loads/LLC-load-misses ...) in guest to
    trigger offcore_rsp #GP

    Signed-off-by: Kan Liang <email address hidden>
    Signed-off-by: Peter Zijlstra <email address hidden>
    Cc: Andi Kleen <email address hidden>
    Cc: Arnaldo Carvalho de Melo <email address hidden>
    Cc: Linus Torvalds <email address hidden>
    Cc: Maria Dimakopoulou <email address hidden>
    Cc: Mark Davies <email address hidden>
    Cc: Paul Mackerras <email address hidden>
    Cc: Stephane Eranian <email address hidden>
    Cc: Yan, Zheng <email address hidden>
    Link: http://<email address hidden>
    Signed-off-by: Ingo Molnar <email address hidden>