Ironically the revenge of microkernels, as most cloud workloads run on type 1 hypervisors.
It gets a bit blurry on AArch64 without and with VHE (Virtual Host Extensions) as without VHE (< ARMv8.1) the kernel runs in EL1 ("kernel mode") most of the time and escalates to EL2 ("hypervisor mode") only when needed, but with VHE it runs at EL2 all the time. (ref. https://lwn.net/Articles/650524/)
* VMM is treated as synonymous with hypervisor
* "Extended host" is defined as "A pseudo-machine [99], also called an extended machine [53] or a user machine [75], is a composite machine produced through a combination of hardware and software, in which the machine's apparent architecture has been changed slightly to make the machine more convenient to use. Typically these architectural changes have taken the form of removing I/O channels and devices, and adding system calls to perform I/O and and other operations"
In other words, type 1 ("bare machine hypervisor") runs in supervisor mode and type 2 runs in user mode. QEMU running in dynamic binary translation mode is a type 2 VMM.
KVM runs on a bare machine, but it delegates some services to a less privileged component such as QEMU or crosvm or Firecracker. This is not a type 2 hypervisor, it is a type 1 hypervisor that follows security principles such as privilege separation.
So it's true that "most cloud workloads run on type 1 hypervisors" (KVM is one) but not that most cloud vendors/workloads run on microkernel-like hypervisors, with the exception of Azure.
