As discussed in this thread:
https://lore.kernel.org/kvm/[email protected]/
Let's remove VFIO_GROUP_NOTIFY_SET_KVM and instead assume the association
has already been established prior to device_open. For the types today
that need a KVM (GVT, vfio-ap) these will fail if a KVM is not found.
Looking ahead, vfio-pci-zdev will optionally want the KVM association
(enable hardware assists) but it will not be a hard requirement (still
want to allow other, non-KVM userspace usage).
This is built on top of Jason's group locking series:
https://github.com/jgunthorpe/linux/commits/vfio_group_locking
And tested with s390x-pci (zdev-kvm series) and vfio-ap (GVT changes are
compile-tested only)
Changes for v2:
- gvt no longer needs release_work, get rid of it (Christoph)
- a few compile fixes for gvt
- update commit to mention fixes gvt oops (Jason)
- s/down_write/down_read/ in a few spots (Jason)
- avoid kvm build dependency by holding group read lock over device
open/close and put the onus on the driver to obtain a reference if
it will actually use the kvm pointer. Document the requirement,
use lockdep_assert to ensure lock is held during register_notifer;
today all callers are from driver open_device.
Matthew Rosato (1):
vfio: remove VFIO_GROUP_NOTIFY_SET_KVM
drivers/gpu/drm/i915/gvt/gtt.c | 4 +-
drivers/gpu/drm/i915/gvt/gvt.h | 3 -
drivers/gpu/drm/i915/gvt/kvmgt.c | 82 ++++++---------------------
drivers/s390/crypto/vfio_ap_ops.c | 38 ++++---------
drivers/s390/crypto/vfio_ap_private.h | 3 -
drivers/vfio/vfio.c | 75 ++++++++----------------
include/linux/vfio.h | 5 +-
7 files changed, 56 insertions(+), 154 deletions(-)
--
2.27.0