KVM: fix userspace ABI breakage

The following part of commit 9ef621d3


(KVM: Support mixed endian machines) changed on the size of a struct
that is exported to userspace:

include/linux/kvm.h:

@@ -318,14 +318,14 @@ struct kvm_trace_rec {
 	__u32 vcpu_id;
 	union {
 		struct {
-			__u32 cycle_lo, cycle_hi;
+			__u64 cycle_u64;
 			__u32 extra_u32[KVM_TRC_EXTRA_MAX];
 		} cycle;
 		struct {
 			__u32 extra_u32[KVM_TRC_EXTRA_MAX];
 		} nocycle;
 	} u;
-};
+} __attribute__((packed));

Packing a struct was the correct idea, but it packed the wrong struct.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>