On 03/01/2019 04:38 AM, Cornelia Huck wrote:
[This is the Linux kernel part, git tree is available at
https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw.git vfio-ccw-eagain-caps-v3
The companion QEMU patches are available at
https://github.com/cohuck/qemu vfio-ccw-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 introduces capabilities (similar to what vfio-pci uses)
and exposes a new async region for handling hsch/csch.
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.
Hi Connie,
Thanks for the updated branches! I promise that I'll get back to
reviewing them "soon," though I've been on some other tangents as of late.
In terms of testing, Farhan and I have been playing around with some
exercisers/data pushers both with and without your new code, and things
seem to be okay. Some of the problems we've reproduced without this
code (and would fall into the area Pierre's FSM code would address), and
some seem wholly unrelated. We're looking into them, but didn't want a
whole week to go by without you hearing anything on this series.
If I have nothing meaningful tomorrow, enjoy your weekend!
- Eric
Changes v3->v4:
- shrunk the capability offset, we don't need to accommodate as much as pci
- make checks in patch 1 more consistent and less buggy
- rebased on top of my current vfio-ccw branch
Changes v2->v3:
- Unb0rked patch 1, improved scope
- Split out the new mutex from patch 2 into new patch 3; added missing
locking and hopefully improved description
- Patch 2 now reworks the state handling by splitting the BUSY state
into CP_PROCESSING and CP_PENDING
- Patches 3 and 5 adapted on top of the reworked patches; hsch/csch
are allowed in CP_PENDING, but not in CP_PROCESSING (did not add
any R-b due to that)
- Added missing free in patch 5
- Probably some small changes I forgot to note down
Changes v1->v2:
- New patch 1: make it safe to use the cp accessors at any time; this
should avoid problems with unsolicited interrupt handling
- New patch 2: handle concurrent accesses to the io region; the idea is
to return -EAGAIN to userspace more often (so it can simply retry)
- also handle concurrent accesses to the async io region
- change VFIO_REGION_TYPE_CCW
- merge events for halt and clear to a single async event; this turned out
to make the code quite a bit simpler
- probably some small changes I forgot to note down
Cornelia Huck (6):
vfio-ccw: make it safe to access channel programs
vfio-ccw: rework ssch state handling
vfio-ccw: protect the I/O region
vfio-ccw: add capabilities chain
s390/cio: export hsch to modules
vfio-ccw: add handling for async channel instructions
drivers/s390/cio/Makefile | 3 +-
drivers/s390/cio/ioasm.c | 1 +
drivers/s390/cio/vfio_ccw_async.c | 88 ++++++++++++
drivers/s390/cio/vfio_ccw_cp.c | 21 ++-
drivers/s390/cio/vfio_ccw_cp.h | 2 +
drivers/s390/cio/vfio_ccw_drv.c | 57 ++++++--
drivers/s390/cio/vfio_ccw_fsm.c | 143 +++++++++++++++++-
drivers/s390/cio/vfio_ccw_ops.c | 215 +++++++++++++++++++++++-----
drivers/s390/cio/vfio_ccw_private.h | 48 ++++++-
include/uapi/linux/vfio.h | 4 +
include/uapi/linux/vfio_ccw.h | 12 ++
11 files changed, 537 insertions(+), 57 deletions(-)
create mode 100644 drivers/s390/cio/vfio_ccw_async.c
