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RFC vfio-ccw: support for {halt,clear} subchannel

Cornelia Huck kvm linux-s390 lkml qemu-devel 1 version In review

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  1. v1 RFC Latest2 patches 27 repliesIn review

Patches in v1 No applies recorded yet

#Subject and filesSizeRepliesApplied
1/2s390/cio: export hsch to modulesdrivers/s390/cio/ioasm.c+1 -01 reply
2/2vfio-ccw: support for halt/clear subchanneldrivers/s390/cio/vfio_ccw_drv.c drivers/s390/cio/vfio_ccw_fsm.c+92 -1226 replies

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PatchPierre Morel
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Read the v1 thread

Cover letter [PATCH RFC 0/2] vfio-ccw: support for {halt,clear} subchannel

Hi,

this (RFC) is an initial stab at passing the halt and clear subchannel operations to the host device. Today, host userspace is emulating those two operations, but we really want to execute them on the host device (e.g. for error recovery situations).

The nice thing about this approach is that is independent from userspace
changes: Unless userspace forwards halt/clear requests, we behave as before. Conversely, userspace can simply try to submit halt/clear, and old kernels will simply indicate that it is not supported.

This survives triggering clear subchannel in the guest (hacked in by myself) together with an update QEMU (to be posted in a moment).

Obviously, this needs some more work. Better support for async handling comes to mind. We probably also want to support other channel I/O instructions.

Cornelia Huck (2):
s390/cio: export hsch to modules
vfio-ccw: support for halt/clear subchannel

 drivers/s390/cio/ioasm.c        |  1 +
 drivers/s390/cio/vfio_ccw_drv.c | 10 ++++-
 drivers/s390/cio/vfio_ccw_fsm.c | 94 ++++++++++++++++++++++++++++++++++++-----
 3 files changed, 93 insertions(+), 12 deletions(-)
Signature · 1 line
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