+ while (1) {
+ mem = kvm_lookup_overlapping_slot(s, start_addr, start_addr + size);
+ if (!mem) {
+ break;
+ }
+
+ if (flags < IO_MEM_UNASSIGNED && start_addr >= mem->start_addr &&
+ (start_addr + size <= mem->start_addr + mem->memory_size) &&
+ (phys_offset - start_addr == mem->phys_offset - mem->start_addr)) {
+ /* The new slot fits into the existing one and comes with
+ * identical parameters - nothing to be done. */
+ return;
+ }
+
+ old = *mem;
+
+ /* unregister the overlapping slot */
+ mem->memory_size = 0;
+ err = kvm_set_user_memory_region(s, mem);
+ if (err) {
+ fprintf(stderr, "%s: error unregistering overlapping slot: %s\n",
+ __func__, strerror(-err));
+ abort();
+ }
+
+ /* Workaround for older KVM versions: we can't join slots, even not by
+ * unregistering the previous ones and then registering the larger
+ * slot. We have to maintain the existing fragmentation. Sigh.
+ *
+ * This workaround assumes that the new slot starts at the same
+ * address as the first existing one. If not or if some overlapping
+ * slot comes around later, we will fail (not seen in practice so far)
+ * - and actually require a recent KVM version. */
+ if (s->broken_set_mem_region &&
+ old.start_addr == start_addr && old.memory_size < size &&
+ flags < IO_MEM_UNASSIGNED) {
+ mem = kvm_alloc_slot(s);
+ mem->memory_size = old.memory_size;
+ mem->start_addr = old.start_addr;
+ mem->phys_offset = old.phys_offset;