• Dmitry Bilunov's avatar
    KVM: Handle MSR_IA32_PERF_CTL · 0c2df2a1
    Dmitry Bilunov authored
    Intel CPUs having Turbo Boost feature implement an MSR to provide a
    control interface via rdmsr/wrmsr instructions. One could detect the
    presence of this feature by issuing one of these instructions and
    handling the #GP exception which is generated in case the referenced MSR
    is not implemented by the CPU.
    KVM's vCPU model behaves exactly as a real CPU in this case by injecting
    a fault when MSR_IA32_PERF_CTL is called (which KVM does not support).
    However, some operating systems use this register during an early boot
    stage in which their kernel is not capable of handling #GP correctly,
    causing #DP and finally a triple fault effectively resetting the vCPU.
    This patch implements a dummy handler for MSR_IA32_PERF_CTL to avoid the
    Signed-off-by: default avatarDmitry Bilunov <kmeaw@yandex-team.ru>
    Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
x86.c 215 KB