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Microsoft patents safety check for hardware moved between virtual systems

This patent describes a method for safely moving a hardware device between different virtual environments. Before the device is allowed to access new data, the system places it in an isolated 'probation' mode to test its behavior and clean its software.

Why it mattersThis improves security for data centers by ensuring that reused hardware components are checked for faults or malicious changes before they are assigned to new tasks.

In the filing’s own words

Probation of direct memory access (DMA) device used for direct device assignment. A virtualization computer system identifies a peripheral device as being removed from a direct assignment to a first operating context of a virtualization environment. The peripheral device is DMA capable. The virtualization computer system assigns the peripheral device to a second operating context of the virtualization environment and initiates a device validation against the peripheral device. Based on the device validation indicating that the peripheral device is normal, the virtualization computer system reassigns the peripheral device to a third operating context of the virtualization environment. Based on the device validation indicating that the peripheral device is abnormal, the virtualization computer system excludes the peripheral device from assignment to a third operating context of the virtualization environment.

What exactly they claim (claim 1)

1. A method implemented in a computer system that includes a processor system, comprising: identifying a peripheral device as being removed from a direct assignment to a first operating context of a virtualization environment, wherein the peripheral device is direct memory access (DMA) capable; assigning the peripheral device to a second operating context of the virtualization environment, the second operating context being a probationary operating context that is isolated from memory and data accessible to the first operating context of the virtualization environment; while the peripheral device is assigned to the second operating context: initiating a device validation against the peripheral device, including monitoring a DMA-related signal generated by an input/output memory management unit (IOMMU) to characterize a DMA behavior of the peripheral device; and initiating a cleaning operation on the peripheral device responsive to the device validation, including replacing a firmware on the peripheral device; and reassigning the peripheral device to a third operating context of the virtualization environment after initiating the cleaning operation on the peripheral device.

Facts

Company
Microsoft (Microsoft Technology Licensing, LLC)
Official title
Probation of direct memory access device used for direct device assignment
Patent number
US12769685B2
Application number
18499028
Filed
Oct 31, 2023
Granted
Oct 20, 2026
Inventors
3
Claims
20

Classified under

G06F 13/28 Physics & computingG06F 2213/28 Physics & computing
Read the full filing (official PDF) ↗ Open in the Patent Tracker

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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.