Microsoft patents secure storage layer for virtual machines

1. A method implemented in a computer system that includes a processor system, comprising: loading a container image as a first filesystem volume for use by a guest operating system (OS) of a virtual machine (VM), including: obtaining a root integrity hash that corresponds to the container image; determining that data of the container image has a valid integrity state, including validating a first hash tree stored within the container image based on the root integrity hash; and creating the first filesystem volume as a read-only volume from the container image based on the data of the container image having the valid integrity state; loading a virtual disk image as a second filesystem volume for use by the guest OS, including: generating an ephemeral encryption key, the ephemeral encryption key being stored exclusively within a memory of the VM; creating a filesystem on the virtual disk image, creating the filesystem including: enabling an encryption feature of the filesystem, the encryption feature of the filesystem being configured to encrypt data written to the filesystem based on the ephemeral encryption key; and enabling an integrity protection feature of the filesystem, the integrity protection feature being configured to create a writable second hash tree that stores hashes representing data written to the filesystem; and creating the second filesystem volume as a read-write volume from the filesystem, wherein: when a data block is written to the second filesystem volume, the data block is encrypted based on the ephemeral encryption key, and a hash representing the data block is added to the writable second hash tree; and when the data block is read from the second filesystem volume, the data block is validated using the hash representing the data block; creating a third filesystem volume as a union of the first filesystem volume and the second filesystem volume, wherein writes to the third filesystem volume are directed to the second filesystem volume; and exposing the third filesystem volume as a system volume for the guest OS.