diff options
Diffstat (limited to 'Documentation/virt/kvm/locking.rst')
| -rw-r--r-- | Documentation/virt/kvm/locking.rst | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/Documentation/virt/kvm/locking.rst b/Documentation/virt/kvm/locking.rst index 1fc860c007a3..5d27da356836 100644 --- a/Documentation/virt/kvm/locking.rst +++ b/Documentation/virt/kvm/locking.rst @@ -16,14 +16,25 @@ The acquisition orders for mutexes are as follows: - kvm->slots_lock is taken outside kvm->irq_lock, though acquiring them together is quite rare. +- Unlike kvm->slots_lock, kvm->slots_arch_lock is released before + synchronize_srcu(&kvm->srcu). Therefore kvm->slots_arch_lock + can be taken inside a kvm->srcu read-side critical section, + while kvm->slots_lock cannot. + +- kvm->mn_active_invalidate_count ensures that pairs of + invalidate_range_start() and invalidate_range_end() callbacks + use the same memslots array. kvm->slots_lock and kvm->slots_arch_lock + are taken on the waiting side in install_new_memslots, so MMU notifiers + must not take either kvm->slots_lock or kvm->slots_arch_lock. + On x86: - vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock -- kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock is - taken inside kvm->arch.mmu_lock, and cannot be taken without already - holding kvm->arch.mmu_lock (typically with ``read_lock``, otherwise - there's no need to take kvm->arch.tdp_mmu_pages_lock at all). +- kvm->arch.mmu_lock is an rwlock. kvm->arch.tdp_mmu_pages_lock and + kvm->arch.mmu_unsync_pages_lock are taken inside kvm->arch.mmu_lock, and + cannot be taken without already holding kvm->arch.mmu_lock (typically with + ``read_lock`` for the TDP MMU, thus the need for additional spinlocks). Everything else is a leaf: no other lock is taken inside the critical sections. |