kvm: nVMX: Fetch VM_INSTRUCTION_ERROR from vmcs02 on vmx->fail

When forwarding a hardware VM-entry failure to L1, fetch the
VM_INSTRUCTION_ERROR field from vmcs02 before loading vmcs01.

(Note that there is an implicit assumption that the VM-entry failure was
on the first VM-entry to vmcs02 after nested_vmx_run; otherwise, L1 is
going to be very confused.)

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Feiner <pfeiner@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/vmx.c

@@ -10755,6 +10755,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+	u32 vm_inst_error = 0;
 
 	/* trying to cancel vmlaunch/vmresume is a bug */
 	WARN_ON_ONCE(vmx->nested.nested_run_pending);
@@ -10767,6 +10768,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 				 vmcs12->vm_exit_msr_store_count))
 		nested_vmx_abort(vcpu, VMX_ABORT_SAVE_GUEST_MSR_FAIL);
 
+	if (unlikely(vmx->fail))
+		vm_inst_error = vmcs_read32(VM_INSTRUCTION_ERROR);
+
 	vmx_load_vmcs01(vcpu);
 
 	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
@@ -10843,7 +10847,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	 */
 	if (unlikely(vmx->fail)) {
 		vmx->fail = 0;
-		nested_vmx_failValid(vcpu, vmcs_read32(VM_INSTRUCTION_ERROR));
+		nested_vmx_failValid(vcpu, vm_inst_error);
 	} else
 		nested_vmx_succeed(vcpu);
 	if (enable_shadow_vmcs)