Messages in this thread | | | Date | Mon, 9 Jan 2023 16:13:27 -0400 | From | Jason Gunthorpe <> | Subject | Re: [PATCH 1/2] KVM: async kvm_destroy_vm for vfio devices |
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On Mon, Jan 09, 2023 at 03:10:36PM -0500, Matthew Rosato wrote: > Currently it is possible that the final put of a KVM reference comes from > vfio during its device close operation. This occurs while the vfio group > lock is held; however, if the vfio device is still in the kvm device list, > then the following call chain could result in a deadlock: > > kvm_put_kvm > -> kvm_destroy_vm > -> kvm_destroy_devices > -> kvm_vfio_destroy > -> kvm_vfio_file_set_kvm > -> vfio_file_set_kvm > -> group->group_lock/group_rwsem > > Avoid this scenario by adding kvm_put_kvm_async which will perform the > kvm_destroy_vm asynchronously if the refcount reaches 0. > > Fixes: 421cfe6596f6 ("vfio: remove VFIO_GROUP_NOTIFY_SET_KVM") > Reported-by: Alex Williamson <alex.williamson@redhat.com> > Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> > --- > drivers/gpu/drm/i915/gvt/kvmgt.c | 6 +++++- > drivers/s390/crypto/vfio_ap_ops.c | 7 ++++++- > include/linux/kvm_host.h | 3 +++ > virt/kvm/kvm_main.c | 22 ++++++++++++++++++++++ > 4 files changed, 36 insertions(+), 2 deletions(-)
Why two patches?
It looks OK to me
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
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