WIP: crypto: Add a native feature flag

[smalis-msft]

Binaries who care about having specifically the native backend need a way to ensure a different backend isn't being silently chosen instead.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a crypto/native feature flag intended to prevent consumers from accidentally building against an unintended crypto backend by requiring an explicit backend choice.

Changes:

• Introduces a new native feature in support/crypto, and updates build.rs backend-selection logic to account for it.
• Updates several crates to enable crypto/native (and in some cases vendored) explicitly.
• Adjusts openvmm_entry to depend on crypto with native enabled and updates metadata comments accordingly.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
vm/vmgs/vmgstool/Cargo.toml	Extends the encryption feature to force crypto/native (and vendored).
vm/vmgs/vmgs_lib/Cargo.toml	Enables crypto/native (and vendored) on the crypto dependency.
vm/devices/firmware/firmware_uefi/Cargo.toml	Pins crypto to the native feature and adds a TODO comment.
support/crypto/build.rs	Adds native to backend feature detection and changes backend-selection failure behavior.
support/crypto/Cargo.toml	Defines the new native feature.
openvmm/openvmm_entry/Cargo.toml	Makes crypto non-optional and enables native; updates a metadata comment.

Comments suppressed due to low confidence (1)

support/crypto/build.rs:1

• This changes the contract from 'no backend selected => pick platform default' to 'no backend selected => hard error'. That’s a breaking behavior change (especially for transitive dependents) and is stricter than the PR description implies (it asks for a way for binaries that care, not a new requirement for everyone). Consider restoring the previous default-selection behavior when backend_count == 0 (treat it like native), or alternatively make native a default feature in support/crypto/Cargo.toml so existing dependents continue to build without needing an explicit feature.

// Copyright (c) Microsoft Corporation.