KVM: nVMX: Verify VMCS shadowing VMCS link pointer
Intel SDM considers these checks to be part of "Checks on Guest Non-Register State". Note that it is legal for vmcs->vmcs_link_pointer to be -1ull when VMCS shadowing is enabled. In this case, any VMREAD/VMWRITE to shadowed-field sets the ALU flags for VMfailInvalid (i.e. CF=1). Signed-off-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -11755,6 +11755,33 @@ static int check_vmentry_prereqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
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return 0;
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}
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static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
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struct vmcs12 *vmcs12)
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{
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int r;
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struct page *page;
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struct vmcs12 *shadow;
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if (vmcs12->vmcs_link_pointer == -1ull)
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return 0;
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if (!page_address_valid(vcpu, vmcs12->vmcs_link_pointer))
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return -EINVAL;
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page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->vmcs_link_pointer);
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if (is_error_page(page))
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return -EINVAL;
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r = 0;
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shadow = kmap(page);
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if (shadow->hdr.revision_id != VMCS12_REVISION ||
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shadow->hdr.shadow_vmcs != nested_cpu_has_shadow_vmcs(vmcs12))
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r = -EINVAL;
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kunmap(page);
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kvm_release_page_clean(page);
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return r;
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}
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static int check_vmentry_postreqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
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u32 *exit_qual)
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{
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@ -11766,8 +11793,7 @@ static int check_vmentry_postreqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
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!nested_guest_cr4_valid(vcpu, vmcs12->guest_cr4))
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return 1;
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if (!nested_cpu_has_shadow_vmcs(vmcs12) &&
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vmcs12->vmcs_link_pointer != -1ull) {
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if (nested_vmx_check_vmcs_link_ptr(vcpu, vmcs12)) {
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*exit_qual = ENTRY_FAIL_VMCS_LINK_PTR;
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return 1;
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}
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