On 27/06/2017 03:47, Wanpeng Li wrote: > - wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED); > + pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT | KVM_ASYNC_PF_ENABLED; > + wrmsr_safe(MSR_KVM_ASYNC_PF_EN, pa & 0xffffffff, pa >> 32); > __this_cpu_write(apf_reason.enabled, 1); Better: pa |= KVM_ASYNC_PF_ENABLED; /* Async page fault support for L1 hypervisor is optional. */ if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) < 0) wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); Thanks, Paolo