Allocate MMIO ranges & GSIs

[andreeaflorescu]

Implement an abstraction for generating unique MMIO configurations (address ranges and interrupt numbers).

At the moment the vmm-reference only supports configuring one block device and one network device on the MMIO bus. Each of these devices have a predefined interrupt number and MMIO range assigned. As we add the RTC & Serial Console devices on the MMIO bus (for the aarch64 support) handling these in a static way becomes challenging. The legacy devices are typically using a fixed GSI for interrupts (i.e. serial port 1 uses GSI 4), and the static initialization is not allowing us to extend the vmm-reference to have more than one device type.

There were some discussions at some point to implement a SystemAllocator in rust-vmm. We should see what is the best way of upstreaming this functionality such that it can be reused by multiple VMMs. As a starting point, we can provide a POC in vmm-reference, and in parallel propose a new crate (or update vm-device).

The system allocator is also needed for adding PCI support.

(This issue should be moved to where we are going to implement the vm-allocator).

[AlexandruCihodaru]

What about integrating vm-allocator?

[andreeaflorescu]

What about integrating vm-allocator?

I think this is the right path forward, this issue was created before we implemented the vm-allocator crate.