[Qemu-devel] [PATCH 0/8] Various USB fixes and improvements (update 2)

[Max Krasnyansky <maxk@kernel.org>]

This is an updated version of the USB patches I sent out yesterday.
It includes changes and fixes suggested by Anthony.

This time I also did more testing with XP running on top of QEMU/KQEMU
(used to be QEMU/KVM).

Max Krasnyansky (8):
  husb: support for USB host device auto disconnect.
  husb: support for USB host device auto connect.
  usb:  generic packet handler cleanup and documentation
  uhci: rewrite UHCI emulator, fully async operation with multiple
        outstanding transactions
  husb: rewrite Linux host USB layer, fully async operation
  husb: remove disconnect detection timer
  husb: fixup printfs and stuff based on the review comments
  uhci: fixes for save/load-vm

 hw/usb-uhci.c |  905 ++++++++++++++++++++++++++++++++++-----------------------
 hw/usb.c      |  265 +++++++++--------
 hw/usb.h      |   37 +++-
 usb-linux.c   |  645 +++++++++++++++++++++++-----------------
 vl.c          |   83 +++---
 5 files changed, 1138 insertions(+), 797 deletions(-)

----
Here is the original description.

This patch series started when I tried to share USB ports between 
four instances of Windows XP running on the same Linux box (under KVM).
I quickly realized that current USB support is not very flexible. We do
not handle devices disconnects, there is not way to assign certain USB
ports to VM instance, etc.

Once I fixed that I discovered that USB devices that I absolutely need
in the VMs (Xilinx and Altera USB dongles) do not really work with
QEMU. VMs were getting stuck, applications unhappy, etc.
So I endded up rewriting UHCI and Linux host USB layers to make them 
fully async and to support multiple outstanding transactions.

The result is quite nice. We can now assign USB buses to VM instances 
and devices are automatically connected to the VMs. Just do 
    usb_add host:N.*
in the console or -usbdevice command line option (N is the bus number).
Also when device is disconnected from the host it's automatically removed
from the guest.

Host USB devices operate in fully async mode (except the control transfers).
All the stalls and jerkiness due to long synchronous transactions is gone.
I can easily hook up four different USB devices (mouse, CF card reader, 
phone, Xilinx dongle) and everything is working perfectly. Mouse movements
are silky smooth :).

I did some profiling with OProfile and we seems to be doing ok while XP is 
pumping ~10 MBytes over USB (reported by one of the apps I'm using). UHCI 
stuff is well below VNC for example.

There is more work to be done (async control transfers for example). But I 
think this is way better than what we have now and is ready for more testing
by wider audience. 

Most of the testing so far was done with KVM flavor of QEMU. I did test 
generic i386-softmmu target a bit, it's too slow for any serious testing 
with XP. I did full compile (all targets) too and it went fine.