Assert that slots_lock is held in kvm_dirty_ring_reset() and add a comment to explain _why_ slots needs to be held for the duration of the reset. Link: https://lore.kernel.org/all/aCSns6Q5oTkdXUEe@xxxxxxxxxx Suggested-by: James Houghton <jthoughton@xxxxxxxxxx> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- virt/kvm/dirty_ring.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c index 54734025658a..1ba02a06378c 100644 --- a/virt/kvm/dirty_ring.c +++ b/virt/kvm/dirty_ring.c @@ -122,6 +122,14 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring, unsigned long mask = 0; struct kvm_dirty_gfn *entry; + /* + * Ensure concurrent calls to KVM_RESET_DIRTY_RINGS are serialized, + * e.g. so that KVM fully resets all entries processed by a given call + * before returning to userspace. Holding slots_lock also protects + * the various memslot accesses. + */ + lockdep_assert_held(&kvm->slots_lock); + while (likely((*nr_entries_reset) < INT_MAX)) { if (signal_pending(current)) return -EINTR; -- 2.49.0.1112.g889b7c5bd8-goog
