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>

1 files changed, 14 insertions, 15 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d20c320a33d..9ca014da134d 100644
--- 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: