KVM: nVMX: Fix nested vmexit ack intr before load vmcs01

An external interrupt will cause a vmexit with reason "external interrupt"
when L2 is running.  L1 will pick up the interrupt through vmcs12 if
L1 set the ack interrupt bit.  Commit 77b0f5d6 (KVM: nVMX: Ack and write
vector info to intr_info if L1 asks us to) retrieves the interrupt that
belongs to L1 before vmcs01 is loaded.

This will lead to problems in the next patch, which would write to SVI
of vmcs02 instead of vmcs01 (SVI of vmcs02 doesn't make sense because
L2 runs without APICv).
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Tested-by: NLiu, RongrongX <rongrongx.liu@intel.com>
Tested-by: NFelipe Reyes <freyes@suse.com>
Fixes: 77b0f5d6
Cc: stable@vger.kernel.org
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
[Move tracepoint as well. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -8754,6 +8754,8 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info,
 		       exit_qualification);
 
+	vmx_load_vmcs01(vcpu);
+
 	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
 	    && nested_exit_intr_ack_set(vcpu)) {
 		int irq = kvm_cpu_get_interrupt(vcpu);
@@ -8769,8 +8771,6 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 				       vmcs12->vm_exit_intr_error_code,
 				       KVM_ISA_VMX);
 
-	vmx_load_vmcs01(vcpu);
-
 	vm_entry_controls_init(vmx, vmcs_read32(VM_ENTRY_CONTROLS));
 	vm_exit_controls_init(vmx, vmcs_read32(VM_EXIT_CONTROLS));
 	vmx_segment_cache_clear(vmx);