[Qemu-ppc] Bug with REPORT LUNS in IBM VSCSI

[Nathan Whitehorn]

I'm having some trouble with the VSCSI emulation in the pSeries machine. 
It seems that the emulated SCSI target device on the SRP IT_nexus 
properly distributes SCSI commands to its children but does not report 
them in response to a REPORT LUNS request. This happens because it 
forwards REPORT LUNs to target 0 on its child bus instead of answering 
the command itself. This prevents at least FreeBSD from seeing any QEMU 
SCSI device that is not internally a LUN on QEMU target 0.

I can try to draw up a patch, but it would be nice to know if a fix is 
already in progress first. There seemed to be some patches two years ago 
from Paolo Bonzini to add proper support for hierarchical LUNs, but they 
seem to have never been committed.
-Nathan