[This is the QEMU part, git tree is available at https://github.com/cohuck/qemu vfio-ccw-caps
The companion Linux kernel patches are available at https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw.git vfio-ccw-eagain-caps] Currently, vfio-ccw only relays START SUBCHANNEL requests to the real device. This tends to work well for the most common 'good path' scenarios; however, as we emulate {HALT,CLEAR} SUBCHANNEL in QEMU, things like clearing pending requests at the device is currently not supported. This may be a problem for e.g. error recovery. This patch series makes use of the newly introduced async command region to issue hsch/csch; if it is not present, continue to emulate hsch/csch, as before. Note that the kernel side now returns -EAGAIN to trigger a retry in more cases; QEMU should already be fine with that. [I'm not quite happy with how this async processing hooks up in css.c; ideas welcome.] Lightly tested (I can interact with a dasd as before, and reserve/release seems to work well.) Not sure if there is a better way to test this, ideas welcome. Changes v1->v2: - update kernel header to v2 of kernel patches - rebased on master Cornelia Huck (2): vfio-ccw: new capability chain support vfio-ccw: support async command subregion hw/s390x/css.c | 27 ++++++-- hw/vfio/ccw.c | 109 ++++++++++++++++++++++++++++++++- include/hw/s390x/s390-ccw.h | 3 + linux-headers/linux/vfio.h | 4 ++ linux-headers/linux/vfio_ccw.h | 12 ++++ 5 files changed, 149 insertions(+), 6 deletions(-) -- 2.17.2
