Stalling of DMA operations in order to do memory migration using a migration in progress bit in the translation control entry mechanism

An apparatus for stalling direct memory access operations, the apparatus comprising:

• an input/output bridge for receiving a request for a direct memory access to a physical page in system memory from an input/output adapter;
• and
• a translation control entry migration control connected to the input/output bridge, wherein the translation control entry migration control comprises a migration control state machine;
• wherein the migration control state machine examines a migration in progress bit in a translation control entry pointing to the physical page in response to the input/output bridge receiving the request, wherein the migration in progress bit indicates whether a migration of the physical page referenced in the translation control entry to another location in system memory is in progress;
• and
• wherein the migration control state machine stalls, for the physical page being migrated, the direct memory access from the input/output adapter while continuing other direct memory access operations from the input/output adapter and from other input/output adapters to other physical pages in system memory if the migration in progress bit indicates a migration of the physical page is in progress.

A data processing system for stalling direct memory access operations, the data processing system comprising:

• a bus;
• a storage device connected to the bus, wherein the storage device contains computer usable code;
• at least one managed device connected to the bus;
• and
• a processing unit connected to the bus, wherein the processing unit executes the computer usable code to examine a migration in progress (MIP) bit in a translation control entry (TCE) holding register that is set to a value to indicate whether a page address in the TCE is associated with a physical page in migration;
• determine, based on the value of the MIP bit, whether a page address referenced in a TCE table corresponds with a physical page being migrated to another location in a system memory;
• and stall, only for the physical page being migrated, all DMA operations from an input/output (I/O) adapter corresponding only to the physical page being migrated, responsive to the value of the MIP bit being set to indicate that the physical page being migrated corresponds to the referenced page address in the TCE.