Confidential virtual machine using state-seperated storage architecture

Patent metadata

Field	Value
Publication number	US-12574262-B2
Application number	US-202418590626-A
Country	US
Kind code	B2
Filing date	Feb 28, 2024
Priority date	Feb 28, 2024
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

Abstract

Examples of the present disclosure describe systems and methods for implementing a confidential virtual machine generation system. In examples, read-only and read-write volumes are generated to store operating system binaries and user-generated content, respectively, on filesystems indexed using hash trees. The hash values of the roots of the two hash trees are stored in a location accessed as part of loading an operating system. The example system accesses the roots of the two hash trees to access the current state of read-only and read-write volumes and verify the states using a checksum. The verified states are merged to generate an operating system image associated image with the confidential virtual machine. Additionally, the system merges the namespaces of filesystems of read-only and read-write volumes into a single filesystem namespace concealing multiple volumes.

First claim

What is claimed is:

1 . A system comprising:
a processor unit; and memory coupled to the processing unit, the memory comprising computer executable instructions that, when executed, perform operations comprising:
determining a current state of a read-only volume by accessing a first root of a first hash tree, wherein the first hash tree stores a history of a state of the read-only volume;
determining a current state of a read-write volume by accessing a second root of a second hash tree, wherein the second hash tree stores a history of a state of the read-write volume;
validating operating system binaries in the current state of the read-only volume;
validating user-generated content in the current state of the read-write volume;
merging the operating system binaries and the user-generated content to generate an image of an operating system associated with a confidential virtual machine; and
merging a first namespace of the read-only volume and a second namespace of the read-write volume into a unified single filesystem namespace.

2 . The system of claim 1 , wherein the operations further comprise:
identifying an update to the operating system, wherein the update includes an updated operating system binary of the operating system binaries stored on the read-only volume; and storing the update to the read-write volume as the user-generated content.

3 . The system of claim 2 , the operations further comprise:
accessing the update stored in the read-write volume; validating the update of the operating system binaries by matching a signature provided along with the update and a signature associated with the read-write volume; merging the one or more system binaries in the read-only volume with the update operating system binary in the read-write volume to generate an updated operating system; generating an image of the updated operating system; mounting the image of the updated operating system on the read-only volume; and rebooting the confidential virtual machine to load the updated operating system.

4 . The system of claim 2 , wherein identifying an update to the operating system further comprises:
contacting an update server to request a download of the updated operating system.

5 . The system of claim 3 , wherein rebooting the confidential virtual machine to load the updated operating system further comprises:
identifying updates performed using a transformer, wherein the transformer updates filesystem layout of the read-write volume; changing boot flow from loading the updated operating system to boot a minimal operating system to invoke the transformer; and changing the boot flow from the minimal operating system to boot the updated operating system.

6 . The system of claim 5 , wherein changing the boot flow for loading the updated operating system to boot a minimal operating system to invoke the transformer further comprises:
based on an output of the transformer, rolling back the update to the operating system, wherein the operations comprise: mounting the operating system on the read-only volume; and rebooting the confidential virtual machine to load the operating system.

7 . The system of claim 5 , wherein changing the boot flow from the minimal operating system to boot the updated operating system further comprises:
transmitting a result of loading the updated operating system; and deleting the operating system.

8 . The system of claim 2 , wherein identifying an update to the operating system further comprises:
installing an optional package present on the read-only volume; and updating a registry to include changes to the second namespace of the read-only volume.

9 . The system of claim 8 , wherein the operations further comprise:
merging the operating system binaries and registry entries to generate a second updated operating system associated with the confidential virtual machine; and rebooting the confidential virtual machine to load the second updated operating system.

10 . The system of claim 1 , wherein the operations further comprise:
booting the confidential virtual machine to load the image of the operating system; and presenting the unified single filesystem namespace for interacting with the confidential virtual machine, wherein filesystem namespaces of the read-only volume and the read-write volume are concealed during the presenting.

11 . The system of claim 1 , wherein a hash value of the first root of the first hash tree includes a unique identifier identifying the read-only volume.

12 . The system of claim 1 , wherein a hash value of the first root of the first hash tree includes value of a monotonically increasing virtual clock.

13 . The system of claim 1 , wherein generating the read-write volume to store the user-generated content includes encrypting the read-write volume.

14 . The system of claim 1 , wherein operations further comprise:
generating a registry to manage metadata of the operating system; and overlaying the registry on the read-only volume and the read-write volume.

15 . The system of claim 1 , wherein storing hash values of the first root of the first hash tree and the second root of the second hash tree in a storage further comprises:
storing the first root in a first location that is accessible by unlocking the first location; and storing the second root in a second location different from the first location.

16 . A computer-implemented method for setting up a confidential virtual machine, the method comprising:
generating a read-only volume to store operating system binaries on a first filesystem indexed using a first hash tree; generating a read-write volume to store user-generated content on a second filesystem indexed using a second hash tree; storing hash values of a first root of the first hash tree and a second root of the second hash tree in a storage accessed as part of loading the operating system binaries; instantiating the confidential virtual machine by:
accessing the first root of the first hash tree to determine a current state of the read-only volume;
accessing the second root of the second hash tree to determine the current state of the read-write volume;
verifying the operating system binaries in the current state of the read-only volume;
verifying the user-generated content in the current state of the read-write volume;
merging the operating system binaries and the user-generated content to generate an image of a first operating system image associated with the confidential virtual machine; and
merging a first namespace of the read-only volume and a second namespace of the read-write volume into a unified single filesystem namespace.

17 . The computer implemented method of claim 16 , wherein the method further comprises:
booting the confidential virtual machine to load the image of an operating system; and presenting the unified single filesystem namespace for interacting with the confidential virtual machine, wherein filesystem namespaces of the read-only volume and the read-write volume are concealed during the presenting.

18 . A system comprising:
a processing unit; and memory coupled to the processing unit, the memory comprising computer executable instructions that, when executed perform operations comprising:
identifying operating system binaries to include in an operating system of a confidential virtual machine on a read-only volume;
identifying user-generated content to include in the operating system of the confidential virtual machine on a read-write volume;
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Assignees

• Microsoft Technology Licensing Llc

Inventors

• Das Rajsekhar
• Chagani Shaheed
• Bostanci Hakki Tunc
• Shankar Vinod R
• Parthasarathy Narayanan
• Chitnis Pushkar V
• Abdullateef Ahmad
• Wesemann Matthaus A
• Kishan Arun U

Classifications

• G06F9/45558

  Hypervisor-specific management and integration aspects · CPC title

• G06F8/65

  Updates (security arrangements therefor G06F21/57) · CPC title

• G06F21/57

  Certifying or maintaining trusted computer platforms, e.g. secure boots or power-downs, version controls, system software checks, secure updates or assessing vulnerabilities · CPC title

• G06F2009/45587

  Isolation or security of virtual machine instances · CPC title

• G06F21/575 Primary

  Secure boot · CPC title