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    SubjectRe: [PATCH v10 48/50] KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event
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    On Wed, Oct 18, 2023, Ashish Kalra wrote:
    > > static int snp_handle_ext_guest_request(struct vcpu_svm *svm)
    > > {
    > > struct kvm_vcpu *vcpu = &svm->vcpu;
    > > struct kvm *kvm = vcpu->kvm;
    > > struct kvm_sev_info *sev;
    > > unsigned long exitcode;
    > > u64 data_gpa;
    > >
    > > if (!sev_snp_guest(vcpu->kvm)) {
    > > ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, SEV_RET_INVALID_GUEST);
    > > return 1;
    > > }
    > >
    > > data_gpa = vcpu->arch.regs[VCPU_REGS_RAX];
    > > if (!IS_ALIGNED(data_gpa, PAGE_SIZE)) {
    > > ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, SEV_RET_INVALID_ADDRESS);
    > > return 1;
    > > }
    > >
    > > vcpu->run->hypercall.nr = KVM_HC_SNP_GET_CERTS;
    > > vcpu->run->hypercall.args[0] = data_gpa;
    > > vcpu->run->hypercall.args[1] = vcpu->arch.regs[VCPU_REGS_RBX];
    > > vcpu->run->hypercall.flags = KVM_EXIT_HYPERCALL_LONG_MODE;
    > > vcpu->arch.complete_userspace_io = snp_complete_ext_guest_request;
    > > return 0;
    > > }
    > >
    >
    > IIRC, the important consideration here is to ensure that getting the
    > attestation report and retrieving the certificates appears atomic to the
    > guest. When SNP live migration is supported we don't want a case where the
    > guest could have migrated between the call to obtain the certificates and
    > obtaining the attestation report, which can potentially cause failure of
    > validation of the attestation report.

    Where does "obtaining the attestation report" happen? I see the guest request
    and the certificate stuff, I don't see anything about attestation reports (though
    I'm not looking very closely).

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