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, 2 insertions, 2 deletions

diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index cf567d8033d..65a51432c8e 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -78,7 +78,7 @@ static int kvm_iommu_map_memslots(struct kvm *kvm)
         int i, r = 0;
         struct kvm_memslots *slots;
 
-        slots = kvm->memslots;
+        slots = rcu_dereference(kvm->memslots);
 
         for (i = 0; i < slots->nmemslots; i++) {
                 r = kvm_iommu_map_pages(kvm, &slots->memslots[i]);
@@ -214,7 +214,7 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm)
         int i;
         struct kvm_memslots *slots;
 
-        slots = kvm->memslots;
+        slots = rcu_dereference(kvm->memslots);
 
         for (i = 0; i < slots->nmemslots; i++) {
                 kvm_iommu_put_pages(kvm, slots->memslots[i].base_gfn,