regarding 2): latest betas of ChromeOS disable hyperthreading if one enables builtin Linux VM. Seems overzealous to me, as the OS is not multi-tenant usually
I thought that Chrome OS disabled this by default, as MDS crosses privileges boundaries in addition to the VM/host one?
By default on my ChromeOS 81 beta HyperThreading is getting disabled only after you start the linux vm. HT stays disabled until you reboot. There is scheduler flag in chrome://flags, but IME it does nothing