Migrating memory MMIO from a source I/O adapter of a source computing system to a destination I/O adapter of a destination computing system, includes: collecting, by a source hypervisor of the source computing system, MMIO mapping information, where the source hypervisor supports a logical partition on the source computing system and the logical partition is configured for MMIO operations with the source I/O adapter through an MMU; placing, by a destination hypervisor of the destination computing system, the destination I/O adapter in an error state; migrating the logical partition from the source computing system to the destination computing system; configuring, by the destination hypervisor of the destination computing system, the destination computing system for MMIO with the LPAR utilizing the MMIO mapping information collected by the source hypervisor; and restarting the logical partition on the destination computing system, including recovering, by the logical partition, from the error state.