2017-06-27 21:40 GMT+08:00 Paolo Bonzini <pbonzini@xxxxxxxxxx>: > > > On 22/06/2017 04:06, Wanpeng Li wrote: >> From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> >> >> Add an async_page_fault field to vcpu->arch.exception to identify an async >> page fault, and constructs the expected vm-exit information fields. Force >> a nested VM exit from nested_vmx_check_exception() if the injected #PF >> is async page fault. Extending the userspace interface KVM_GET_VCPU_EVENTS >> and KVM_SET_VCPU_EVENTS for live migration. > > I am not sure what would happen if new kernel (that can produce > async_page_fault=1) runs on top of old userspace (that can consume it). > > I think it would be safer to make the new field "nested_apf", and only > set it if in guest_mode, like > > vcpu->arch.exception.nested_apf = > is_guest_mode(vcpu) && fault->async_page_fault; > if (vcpu->arch.exception.nested_apf) > vcpu->arch.apf.nested_apf_token = fault->address; > else > vcpu->arch.cr2 = fault->address; I have already added the same logic in kvm_inject_page_fault in patch 3/4, in addition, there is a guarantee it is in guest mode when we set svm->vmcb->control.xxxx in nested_svm_check_exception, how about just as what we do in nested_vmx_check_exception? + if (svm->vcpu.arch.exception.async_page_fault) + svm->vmcb->control.exit_info_2 = svm->vcpu.arch.apf.nested_apf_token; + else + svm->vmcb->control.exit_info_2 = svm->vcpu.arch.cr2; Regards, Wanpeng Li
