KVM: Mapping IOMMU pages after updating memslot

In kvm_iommu_map_pages(), we need to know the page size via call
kvm_host_page_size(). And it will check whether the target slot
is valid before return the right page size.
Currently, we will map the iommu pages when creating a new slot.
But we call kvm_iommu_map_pages() during preparing the new slot.
At that time, the new slot is not visible by domain(still in preparing).
So we cannot get the right page size from kvm_host_page_size() and
this will break the IOMMU super page logic.
The solution is to map the iommu pages after we insert the new slot
into domain.

Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Tested-by: Patrick Lu <patrick.lu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d20c32..9ca014d 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -873,21 +873,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
                        goto out_free;
        }
 
-       /*
-        * IOMMU mapping:  New slots need to be mapped.  Old slots need to be
-        * un-mapped and re-mapped if their base changes.  Since base change
-        * unmapping is handled above with slot deletion, mapping alone is
-        * needed here.  Anything else the iommu might care about for existing
-        * slots (size changes, userspace addr changes and read-only flag
-        * changes) is disallowed above, so any other attribute changes getting
-        * here can be skipped.
-        */
-       if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
-               r = kvm_iommu_map_pages(kvm, &new);
-               if (r)
-                       goto out_slots;
-       }
-
        /* actual memory is freed via old in kvm_free_physmem_slot below */
        if (change == KVM_MR_DELETE) {
                new.dirty_bitmap = NULL;
@@ -901,6 +886,20 @@ int __kvm_set_memory_region(struct kvm *kvm,
        kvm_free_physmem_slot(&old, &new);
        kfree(old_memslots);
 
+       /*
+        * IOMMU mapping:  New slots need to be mapped.  Old slots need to be
+        * un-mapped and re-mapped if their base changes.  Since base change
+        * unmapping is handled above with slot deletion, mapping alone is
+        * needed here.  Anything else the iommu might care about for existing
+        * slots (size changes, userspace addr changes and read-only flag
+        * changes) is disallowed above, so any other attribute changes getting
+        * here can be skipped.
+        */
+       if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
+               r = kvm_iommu_map_pages(kvm, &new);
+               return r;
+       }
+
        return 0;
 
 out_slots: