Wayland displaying using shared memory between virtual machines

[jkuro-tii]

Description of changes

Add memory sharing mechanism between virtual machines and use it for wayland/waypipe displaying.

Main changes:

Host

• Added the shared memory manager within QEMU.
• Direct Memory Mapping via SysBus:
  • Modified QEMU's code to map shared memory directly into the VM's memory address space using the SysBus interface.
• Option for Defining Shared Memory Manager:
  • Added an option to QEMU for defining a shared memory manager when running VMs.
• BigPages Area Allocation:
  • Allocated shared memory within the BigPages area for optimized memory usage.

GUI and app VMs

1. Linux Driver for Shared Memory and Interrupts:

   • Added a Linux driver to manage shared memory operations and interrupts and creating the /dev/ivshmem device.

2. Memsocket Application for Inter-VM Communication:

   • Introduced the memsocket application to facilitate socket data forwarding between VMs.

3. Integration with Waypipe:

   • Modified Waypipe service options to interface with the memsocket application, enabling seamless communication between VMs.

Checklist for things done

• Summary of the proposed changes in the PR description
• More detailed description in the commit message(s)
• Commits are squashed into relevant entities - avoid a lot of minimal dev time commits in the PR
• Contribution guidelines followed
• Ghaf documentation updated with the commit - https://tiiuae.github.io/ghaf/
• PR linked to architecture documentation and requirement(s) ticket id
• Test procedure described (or includes tests). Select one or more:
  • Tested on Lenovo X1 x86_64
  • Tested on Jetson Orin NX or AGX aarch64
  • Tested on Polarfire riscv64
• Author has run nix flake check --accept-flake-config and it passes
• All automatic Github Action checks pass - see actions
• Author has added reviewers and removed PR draft status

Testing

Run Chromium and other wayland enabled application. Verify that they execute and display properly.
Run performance tests described in documentation

Jira ticket:

https://ssrc.atlassian.net/browse/SP-3805

Documentation:

https://ssrc.atlassian.net/wiki/spaces/~62552e6ffdb60b006927ad98/blog/2022/09/29/612958326/Memory+sharing+between+virtual+machines
https://ssrc.atlassian.net/wiki/spaces/~62552e6ffdb60b006927ad98/pages/825720835/Wayland+displaying+with+shared+memory

Summary of performance

Playing YouTube is smooth, up to a resolution of 2160p. 
CPU consumption by the memsocket application is below 5%, usually 3-6%.
iperf results are presented in documentation

[jenninikko]

Are you planning to add documentation to the repository?

[jkuro-tii]

Updates:

• Refactored Nix code by consolidating most host and VM configuration changes into a single file, improving maintainability.

• Added support for shared memory on the host system, enabling any application utilizing Unix Sockets (e.g. gRPC) to seamlessly run on both the host and within a virtual machine (VM).

• Implemented the shared memory driver in the NixOS build as a kernel module instead of a kernel patch, simplifying maintenance and eliminating the need for kernel rebuilding.

• Replaced the hardcoded ghaf user ID (1000) with a configurable parameter, increasing flexibility.