> Host is supposed to have multiple guests, so this feels like you are > going to prepare for each guest different DTS with different connection > ID. This feels like poor design. DTS is supposed to be relatively static > configuration, not runtime choice vmguestid+1.
> The guest cannot access other configuration channels, can it? If it can, > it would mean it can eavesdrop on other guests? So obviously it cannot. > Therefore from guest point of view this is completely redundant. Guest > cannot use any other value, thus guest should not configure it. The > guest has only one channel and uses only this one which gets to right > place to the host. Thank you for your feedback. Let me explain the connection ID in more detail: 1. Message Port Architecture: - The connection ID specifies which Hyper-V hypervisor message port (mailbox slot) to use for communication between the host and guest - The hypervisor has multiple message ports, but historically VMBus only used one - With the introduction of VTL2 (Virtual Trust Level 2), the control plane can now be hosted in VTL2, requiring different message ports for communication 2. Control Plane Communication: - The VMBus control plane on the host needs to communicate with the VMBus driver in the guest - When the control plane is hosted in VTL2, it requires a different message port than the standard communication path - The connection ID tells the guest whether to use the standard or alternate message port for this control plane communication 3. Message Processing: - Each message is tagged with an ID - If the guest uses an incorrect ID, the host won't recognize the message and will drop it - This is not about choosing between multiple available channels - it's about using the correct mailbox slot for communication 4. Security and Isolation: - Each guest has its private hypervisor mailbox - Multiple guests using the same connection ID cannot interfere with each other - The connection ID is more like a "root ID" that helps enumerate devices on the bus, not a channel selector between guests 5. Dynamic Nature: - The connection ID is specified when the guest starts running - The host can change it during VM lifecycle events (reset/reboot) - This is why the VMBus driver needs to know the connection ID every time the kernel starts - The ID might be different from what it was during the last guest run Thanks, Hardik
