On Fri, 3 Feb 2023 16:50:25 -0500 Matthew Rosato <mjrosato@xxxxxxxxxxxxx> wrote: > 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(-) > Applied to vfio next branch for v6.3. Thanks, Alex
