Re: [PATCH] KVM: Handle MSR_IA32_PERF_CTL
From: Radim KrÄmÃÅ
Date: Tue May 31 2016 - 10:57:31 EST
2016-05-31 17:38+0300, Dmitry Bilunov:
> 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: Dmitry Bilunov <kmeaw@xxxxxxxxxxxxxx>
Applied, thank you.
> arch/x86/kvm/x86.c | 1 +
> 1 file changed, 1 insertion(+)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c805cf4..d0a5b4b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2314,6 +2314,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> case MSR_AMD64_NB_CFG:
> case MSR_FAM10H_MMIO_CONF_BASE:
> case MSR_AMD64_BU_CFG2:
> + case MSR_IA32_PERF_CTL:
> msr_info->data = 0;
> case MSR_K7_EVNTSEL0 ... MSR_K7_EVNTSEL3: