8.1 Marking - What about the tunnel on R5?

The question reads as follows:

8.1 Marking

• The first step in your end-to-end QoS policy is to ensure that all traffic is properly classified. To do so, configure all VoIP signaling and payload traffic initiated from VLANs 4 and 5 to be marked with a DSCP value of CS5 for critical. All non VoIP traffic should be marked with a DSCP value of CS1 for routine.
• Ensure that traffic received by R4 and R5 on any other ports is marked with the DSCP value of CS1.

In the current topology on router R5 there is a tunnel that goes to R1.  The tunnel comes in on interface Ser0/0/0.35 of R5. The book solution for R5 reads as follows:

R5:
ip access-list extended VOIP
 permit tcp any any eq 1720
 permit udp any any range 16384 32767
!
class-map match-all VOIP
 match access-group name VOIP
!
policy-map MARK_VOIP
 class VOIP
  set dscp cs5
 class class-default
  set dscp cs1
!
policy-map SET_DSCP_CS1
 class class-default
  set dscp cs1
!
interface FastEthernet0/0
 service-policy input MARK_VOIP
!
interface FastEthernet0/1
 service-policy input SET_DSCP_CS1
!
interface Serial0/0/0.35 point-to-point
 service-policy input SET_DSCP_CS1

What I'm trying to understand is what happens to the packets that comes into the tunnel interface on R5.  The gre packet is marked correctly inbound (Ser0/0/0.35)  but what happens when the packet is delievered to the tunnel interface.  Will the packets QoS marking come from the GRE header or will it have the marking of the pre-encapsulated packet from R3? 

I'm leaning to think the pre-encapsulated packet will not be affected by R5's QoS markings on Ser0/0/0.35. 

This is making me think 2 ways:

1) you could use a service-policy inbound on the tunnel interface to correctly do the markings

or

2) the markings must be done before the packet is sent to R5

Is my thought pattern correct here or am I completely off base?

Andy