+
+ /* 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 (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;
+ mem->flags = 0;
+
+ err = kvm_set_user_memory_region(s, mem);
+ if (err) {
+ fprintf(stderr, "%s: error updating slot: %s\n", __func__,
+ strerror(-err));
+ abort();
+ }
+
+ start_addr += old.memory_size;
+ phys_offset += old.memory_size;
+ size -= old.memory_size;
+ continue;
+ }
+
+ /* register prefix slot */
+ if (old.start_addr < start_addr) {
+ mem = kvm_alloc_slot(s);
+ mem->memory_size = start_addr - old.start_addr;
+ mem->start_addr = old.start_addr;
+ mem->phys_offset = old.phys_offset;
+ mem->flags = 0;
+
+ err = kvm_set_user_memory_region(s, mem);
+ if (err) {
+ fprintf(stderr, "%s: error registering prefix slot: %s\n",
+ __func__, strerror(-err));
+ abort();
+ }
+ }
+
+ /* register suffix slot */
+ if (old.start_addr + old.memory_size > start_addr + size) {
+ ram_addr_t size_delta;
+
+ mem = kvm_alloc_slot(s);
+ mem->start_addr = start_addr + size;
+ size_delta = mem->start_addr - old.start_addr;
+ mem->memory_size = old.memory_size - size_delta;
+ mem->phys_offset = old.phys_offset + size_delta;
+ mem->flags = 0;
+
+ err = kvm_set_user_memory_region(s, mem);
+ if (err) {
+ fprintf(stderr, "%s: error registering suffix slot: %s\n",
+ __func__, strerror(-err));
+ abort();
+ }
+ }