Looks like the 9p kernel module is broken in some kernels (3.5, 3.11). I ungraded by guest to 3.10.9 and things started working! :)
I just went with a hunch and have no bug reports or anything to share. Now when I googled it,I see there are few other facing the similar problem and have solved it in a similar fashion. https://bugs.archlinux.org/task/36992
-HTH