Hi Alex, Here is the latest group_lock vs kvm lock deadlock fix + a non-fix follow-on to remove the kvm argument from vfio_device_open and vfio_device_first_open. Changes from v3: * Remove device->group->kvm reference in vfio_main by passing the kvm in (Kevin) * Slight re-organization to make it easier for cdev to build upon this later and keep symmetry between get/put (Alex) * Add follow-on patch that removes unused kvm argument (Yi) Changes from v2: * Relocate the new functions back to vfio_main and externalize to call from group (Kevin) since cdev will need this too * s/vfio_kvm_*_kvm/vfio_device_*_kvm/ and only pass device as input. Handle new kvm_ref_lock directly inside vfio_device_get_kvm (Alex) * Add assert_lockdep_held for dev_set lock (Alex) * Internalize error paths for vfio_device_get_kvm_safe and now return void - either device->kvm is set with a ref taken or is NULL (Alex) * Other flow suggestions to make the call path cleaner - Thanks! (Alex) * Can't pass group->kvm to vfio_device_open, as it references the value outside of new lock. Pass device->kvm to minimize changes in this fix (Alex, Yi) Changes from v1: * use spin_lock instead of spin_lock_irqsave (Jason) * clear device->kvm_put as part of vfio_kvm_put_kvm (Yi) * Re-arrange code to avoid referencing the group contents from within vfio_main (Kevin) which meant moving most of the code in this patch to group.c along with getting/dropping of the dev_set lock Matthew Rosato (2): vfio: fix deadlock between group lock and kvm lock vfio: no need to pass kvm pointer during device open drivers/vfio/group.c | 44 +++++++++++++++++++++---- drivers/vfio/vfio.h | 18 +++++++++-- drivers/vfio/vfio_main.c | 70 +++++++++++++++++++++++++++++++++------- include/linux/vfio.h | 2 +- 4 files changed, 113 insertions(+), 21 deletions(-) -- 2.39.1
