diff options
Diffstat (limited to 'virt/kvm/kvm_main.c')
| -rw-r--r-- | virt/kvm/kvm_main.c | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d54f6578a849..0f1f1c7c7a36 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -874,30 +874,30 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm, int as_id, struct kvm_memslots *slots) { struct kvm_memslots *old_memslots = __kvm_memslots(kvm, as_id); - u64 gen; + u64 gen = old_memslots->generation; - /* - * Set the low bit in the generation, which disables SPTE caching - * until the end of synchronize_srcu_expedited. - */ - WARN_ON(old_memslots->generation & 1); - slots->generation = old_memslots->generation + 1; + WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); + slots->generation = gen | KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS; rcu_assign_pointer(kvm->memslots[as_id], slots); synchronize_srcu_expedited(&kvm->srcu); /* - * Increment the new memslot generation a second time. This prevents - * vm exits that race with memslot updates from caching a memslot - * generation that will (potentially) be valid forever. - * + * Increment the new memslot generation a second time, dropping the + * update in-progress flag and incrementing then generation based on + * the number of address spaces. This provides a unique and easily + * identifiable generation number while the memslots are in flux. + */ + gen = slots->generation & ~KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS; + + /* * Generations must be unique even across address spaces. We do not need * a global counter for that, instead the generation space is evenly split * across address spaces. For example, with two address spaces, address - * space 0 will use generations 0, 4, 8, ... while * address space 1 will + * space 0 will use generations 0, 4, 8, ... while address space 1 will * use generations 2, 6, 10, 14, ... */ - gen = slots->generation + KVM_ADDRESS_SPACE_NUM * 2 - 1; + gen += KVM_ADDRESS_SPACE_NUM * 2; kvm_arch_memslots_updated(kvm, gen); |