Patent ID: 7574537

Claim:
A method in a computer system for migrating data pages that are subject to DMA access by temporarily disabling selected DMA operations within a physical I/O adapter, wherein the computer system includes an I/O controller, the method comprising: determining whether to disable data access DMA operations of said physical I/O adapter; setting, by the I/O controller, a mode bit included within the I/O controller which sets an operating mode of said physical I/O adapter to a particular mode utilizing, according to said determination of whether to disable data access DMA operations, wherein the I/O controller sets the mode bit when data access DMA operations are to be disabled; and disabling only data access DMA operations of said physical I/O adapter when said mode bit is set, wherein the I/O controller processes administrative services DMA operations but does not process data access DMA operations continue to be performed while said data access DMA operations of said physical I/O adapter are disabled, and further wherein said administrative services DMA operations are DMA operations that are performed by said physical I/O adapter to access registers that are included within said physical I/O adapter; including, in the physical I/O adapter, a plurality of virtual I/O adapters, wherein each one of the plurality of virtual I/O adapters is a logical representation of the physical I/O adapter, and wherein each one of the plurality of virtual I/O adapters acts independently from all other ones of the plurality of virtual I/O adapters; including, in each one of the plurality virtual I/O adapters, a queue pair, wherein the queue pair includes a send work queue for managing send messages for its virtual I/O adapter and a receive work queue for managing receive messages for its virtual I/O adapter; and including, within the physical I/O adapter, a plurality of DMA channels, wherein each one of the virtual I/O adapters has a dedicated DMA channel.