Virtual mode execution manager

A method, comprising:

• executing a first virtual machine in a first execution mode on a microprocessor, the first virtual machine in the first execution mode using a first subset of a plurality of peripherals that are hardware devices;
• executing a second virtual machine in a second execution mode on the microprocessor, the second virtual machine in the second execution mode using a second subset of the plurality of peripherals;
• sending an indication to mode entry logic circuitry that the first virtual machine is to be changed to execute in a third execution mode, the third execution mode using a third subset of the plurality of peripherals;
• sending a mode change request from the mode entry logic circuitry to virtual execution mode manager circuitry embodied within a hardware device coupled to the microprocessor to execute a state machine generating interrupts to the microprocessor, and in bidirectional communication with the plurality of peripherals, the mode change request indicating that the first virtual machine is to change mode to the third execution mode;
• sending clock gate requests from the virtual execution mode manager circuitry to the third subset of the plurality of peripherals;
• in response to the third subset of the plurality of peripherals completing current tasks, placing the third subset into a clock-gated mode, and sending clock-gate acknowledgements back to the virtual execution mode manager circuitry;
• sending a mode change acknowledgement from the virtual execution mode manager circuitry to the mode entry logic circuitry indicating that the first virtual machine is ready to be changed to the third execution mode;
• changing the first virtual machine to the third execution mode;
• sending a mode change completed indication from the mode entry logic circuitry to the virtual execution mode manager circuitry to indicate that mode change is complete;
• and
• generating an interrupt in response to receipt of the mode change completed indication.

A microcontroller, comprising:

• a microprocessor executing a plurality of virtual machines;
• virtual execution mode manager circuitry comprising a hardware device coupled to the microprocessor and configured to execute a state machine that generates interrupts to the microprocessor;
• a plurality of peripherals, with different ones of the plurality of virtual machines using different subsets of the plurality of peripherals during execution in different modes modes, the plurality of peripherals being hardware devices in bidirectional communication with the hardware device of the virtual execution mode manager circuitry;
• mode change logic circuitry configured to:
• receive a mode change request from the microprocessor, the mode change request indicating which of the plurality of virtual machines are to change execution mode;
• and
• send the mode change request to the virtual execution mode manager circuitry;
• and
• the virtual execution mode manager circuitry configured to, for each virtual machine having its execution mode changed, send clock gate requests to the subset of the plurality of peripherals corresponding to that virtual machine;
• wherein the subset the plurality of peripherals, in response to the clock gate requests, are configured to complete their current operations, enter into a clock-gated state, and send clock-gate acknowledgement signals to the virtual execution mode manager circuitry;
• wherein the virtual execution mode manager circuitry is further configured to, for each virtual machine having its execution mode changed, send a mode change acknowledgement to the mode entry logic circuitry indicating that the execution mode of that virtual machine is ready to be changed;
• wherein the mode change logic circuitry is further configured to, for each virtual machine having its execution mode changed, change the execution mode of that virtual machine, and send a mode change completion indication to the virtual execution mode manager circuitry;
• and
• wherein the virtual execution mode manager circuitry is further configured to, for each virtual machine whose execution mode has changed, generate an interrupt.