Arm Limited

Marc Zyngier

Jason Parker

Hakan Persson

Matt Evans

Martin Weidmann

Timothy Nicholas Hay

William James Deacon

An apparatus comprises processing circuitry which has a hypervisor execution mode for execution of a hypervisor for managing one or more virtual processors executing on the processing circuitry, and at least one less privileged execution mode than the hypervisor execution mode. In response to a conditional yield to hypervisor instruction executed in the at least one less privileged execution mode, an instruction decoder controls the processing circuitry to determine whether at least one trap condition is satisfied, and when the at least one trap condition is determined to be satisfied, to switch the processing circuitry to the hypervisor execution mode; and store, in at least one storage element accessible to instructions executed in the hypervisor execution mode, at least one item of scheduling hint information for estimating whether the at least one trap condition is still satisfied.

Conditional yield to hypervisor instruction

There is provided a data processing apparatus that includes processing circuitry for executing instructions relating to an active virtual processor in a plurality of virtual processors. Exception control circuitry receives an external exception associated with a target virtual processor in the plurality of virtual processors and when the target virtual processor is other than the active virtual processor, it issues a doorbell exception to cause a scheduling operation to schedule the target virtual processor to be the active virtual processor. Storage circuitry stores an indication of a set of masked virtual processors and the scheduling operation is adapted to disregard doorbell exceptions in respect of the set of masked virtual processors.

External exception handling

A data processing system includes one or more processors that each execute one or more operating systems. Each operating system includes one or more applications. An accelerator provides a shared resource for a plurality of the applications and has one or more input/output interfaces for the submission of tasks to the accelerator from an application. A hypervisor manages the allocation of the input/output interfaces to the one or more operating systems and a hypervisor interface enables communication between the hypervisor and the accelerator. The system is capable of being configured such that an operating system that has been allocated an input/output interface is capable of communicating with the accelerator via the input/output interface independently of the hypervisor. A memory management unit is capable of providing an isolated region of a memory for use by the operating system while the operating system retains its allocated input/output interface.

Data processing system and method having an operating system that communicates with an accelerator independently of a hypervisor

A data processing system comprises one or more processors that each execute one or more operating systems. Each operating system includes one or more applications. The system also comprises an accelerator that provides a shared resource for a plurality of the applications, an input/output module comprising one or more input/output interfaces for the submission of tasks to the accelerator, a hypervisor that manages the allocation of the input/output interfaces to the one or more operating systems and a storage area accessible by the hypervisor and the accelerator. The accelerator is capable of writing one or more selected pieces of information representative of one or more scheduling statistics of the accelerator periodically to the storage area without having received a request for the one or more selected pieces of information from the hypervisor.

Methods of and data processing systems for handling an accelerator's scheduling statistics

A data processing system includes one or more processors that each execute one or more operating systems that include one or more applications; an accelerator that provides a shared resource for a plurality of the applications; a storage area accessible by the processors and the accelerator; and one or more input/output interfaces for control of, or the submission of tasks to, the accelerator. To initialize one of the input/output interfaces, one of the one or more processors is capable of sending a first signal to the accelerator; the accelerator is capable of writing one or more selected pieces of information representative of one or more capabilities of the accelerator to the storage area and sending a second signal to the processor; the processor is capable of reading the one or more selected pieces of information from the storage area; and the accelerator is capable of configuring the input/output interface.

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Cambridge, United Kingdom

Marc Zyngier