s390/vfio_ccw: Limit the number of channel program segments

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The processing of channel programs, and the CCWs within them, is done
recursively. As such, there is an arbitrary (but not architectural)
limit to the number of CCWs that can exist in a single channel program.

The vfio-ccw logic breaks these channel programs into segments whenever
it encounters a Transfer-In-Channel (TIC) CCW, and the combined number
of segments count towards the global limit. Impose an equivalent limit
to the number of segments until such logic can be made non-recursive.

Fixes: 0a19e61e6d ("vfio: ccw: introduce channel program interfaces")
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

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Eric Farman 2026-07-28 05:30:14 +02:00 • committed by Christian Borntraeger

parent 74186c2968

commit 5405c90d6a

2 changed files with 14 additions and 0 deletions

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6

drivers/s390/cio/vfio_ccw_cp.c

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8

drivers/s390/cio/vfio_ccw_cp.h

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