Hello, Evgenie Muzychenko, you wrote: I eat> Hello, lpd, you wrote: lpd>> Calls to user-mode a host all the same transit through a host kernel. I eat> That such "calls to user-mode a host" and for what it by all means to transit through its kernel? At least in kvm, the majority of virtual devices (except drivers vhost, emulated by a host kernel) are emulated user-level by the program on a host. VM at first switches in kernel-mode a host, generates event which waits user-level the emulator; after that user-level the emulator is added in queue of the scheduler and it processes request to the device when in it the context switches. How much it will be decelerated because of correction meltdown/spectre I not undertake to judge.