The way that KVM handles debugfs init/destroy is somewhat sloppy. Even though debugfs is stood up after kvm_create_vm(), it is torn down from kvm_destroy_vm(). There exists a window where we need to tear down a VM before debugfs is created, requiring delicate handling. This series cleans up the debugfs lifecycle by fully tying it to the VM's init/destroy pattern. First two patches hoist some unrelated stats initialization to a more appropriate place for kvm and kvm_vcpu. Second two patches are the meat of the series, changing around the initialization order to get an FD early and wiring in debugfs initialization to kvm_create_vm(). Lastly, patch 5 is essentially a revert of Sean's fix [1] for a NULL deref in debugfs, though I stopped short of an outright revert since that one went to stable and is still entirely correct. Applies cleanly to v5.18-rc5, since [1] is currently missing from kvm/queue or kvm/next. Tested with KVM selftests and the reproducer mentioned in [1] on an Intel Skylake machine. [1] 5c697c367a66 ("KVM: Initialize debugfs_dentry when a VM is created to avoid NULL deref") v1: http://lore.kernel.org/r/20220415201542.1496582-1-oupton@xxxxxxxxxx v1 -> v2: - Don't conflate debugfs+stats. Initialize stats_id outside of the context of debugfs (Sean) - Pass around the FD as a string to avoid subsequent KVM changes inappropriately using the FD (Sean) Oliver Upton (5): KVM: Shove vm stats_id init into kvm_create_vm() KVM: Shove vcpu stats_id init into kvm_vcpu_init() KVM: Get an fd before creating the VM KVM: Actually create debugfs in kvm_create_vm() KVM: Hoist debugfs_dentry init to kvm_create_vm_debugfs() (again) virt/kvm/kvm_main.c | 96 +++++++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 47 deletions(-) -- 2.36.1.124.g0e6072fb45-goog