KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update

Use two steps for memslot deletion: mark the slot invalid (which stops
instantiation of new shadow pages for that slot, but allows destruction),
then instantiate the new empty slot.

Also simplifies kvm_handle_hva locking.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index f73de631e3ee..f51e684dd238 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -504,12 +504,12 @@ out:
 static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
                                       struct kvm_assigned_pci_dev *assigned_dev)
 {
-        int r = 0;
+        int r = 0, idx;
         struct kvm_assigned_dev_kernel *match;
         struct pci_dev *dev;
 
         mutex_lock(&kvm->lock);
-        down_read(&kvm->slots_lock);
+        idx = srcu_read_lock(&kvm->srcu);
 
         match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
                                       assigned_dev->assigned_dev_id);
@@ -573,7 +573,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
         }
 
 out:
-        up_read(&kvm->slots_lock);
+        srcu_read_unlock(&kvm->srcu, idx);
         mutex_unlock(&kvm->lock);
         return r;
 out_list_del:
@@ -585,7 +585,7 @@ out_put:
         pci_dev_put(dev);
 out_free:
         kfree(match);
-        up_read(&kvm->slots_lock);
+        srcu_read_unlock(&kvm->srcu, idx);
         mutex_unlock(&kvm->lock);
         return r;
 }