virtio_console: add virtio console device

[jstarks]

Add a new virtio console device that bridges a guest serial port (/dev/hvc0) to any SerialIo backend.

The device uses two virtio queues — receiveq (host→guest) and transmitq (guest→host) — and supports the F_SIZE feature for reporting console dimensions. Multiport (F_MULTIPORT) is not supported.

The implementation handles backend disconnect/reconnect: when the SerialIo backend disconnects, TX descriptors are drained without forwarding until the backend reconnects.

Key changes:

• virtio: add peek/consume API to VirtioQueue, allowing devices to inspect a descriptor chain before deciding whether to consume it. This complements the existing callback-based API and simplifies the console worker loop.

• virtio: add VirtioDevice::enable() return type change from () to anyhow::Result<()>, allowing devices to report enablement failures to the transport layer.

• virtio_console: new crate with device implementation, resolver, spec constants, and integration tests (9 tests covering TX, RX, large payloads, disconnect/reconnect, and disable/re-enable).

• openvmm_entry: wire up --virtio-console CLI flag to instantiate the device with a serial backend.

[github-actions]

⚠️ Unsafe Code Detected

This PR modifies files containing unsafe Rust code. Extra scrutiny is required during review.

For more on why we check whole files, instead of just diffs, check out the Rustonomicon

[Copilot]

Pull request overview

Adds a new virtio-console device implementation (virtio device ID 3) that bridges a guest console (/dev/hvc0) to an existing SerialIo backend, and wires it into OpenVMM’s resource/CLI plumbing. It also extends the virtio queue API to support “peek then consume” descriptor handling and allows VirtioDevice::enable() to report failures.

Changes:

• Introduce new virtio_console crate (device implementation, resolver, spec constants, and integration tests).
• Extend virtio queue handling with a peek/consume API and refactor shared payload-reading helpers; change VirtioDevice::enable() to return anyhow::Result<()>.
• Add --virtio-console CLI flag and resource wiring so the device can be instantiated with a serial backend.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
vm/devices/virtio/virtio_resources/src/lib.rs	Adds a VirtioConsoleHandle resource type for configuring the new device.
vm/devices/virtio/virtio_console/src/lib.rs	Implements the virtio-console device and its async worker loop using peek/consume queues.
vm/devices/virtio/virtio_console/src/resolver.rs	Adds a resolver that instantiates VirtioConsoleDevice from resources.
vm/devices/virtio/virtio_console/src/spec.rs	Defines virtio-console device ID, feature bit, and config layout helpers.
vm/devices/virtio/virtio_console/src/tests.rs	Adds integration tests for RX/TX, disconnect/reconnect, and disable/re-enable scenarios.
vm/devices/virtio/virtio_console/Cargo.toml	Declares the new crate and dependencies.
vm/devices/virtio/virtio/src/queue.rs	Adds core support for peeking at available descriptors without advancing indices.
vm/devices/virtio/virtio/src/common.rs	Adds PeekedWork + helpers and exposes VirtioQueue::{try_peek,poll_peek,peek}.
openvmm/openvmm_resources/src/lib.rs	Registers the new VirtioConsoleResolver.
openvmm/openvmm_resources/Cargo.toml	Adds virtio_console dependency.
openvmm/openvmm_entry/src/cli_args.rs	Adds --virtio-console CLI flag.
openvmm/openvmm_entry/src/lib.rs	Wires CLI flag into VM config construction and adds the virtio-console device resource.
Cargo.toml	Adds virtio_console to workspace members/deps.
Cargo.lock	Records the new workspace crate in the lockfile.

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[github-actions]

At least one Petri test failed.

[github-actions]

At least one Petri test failed.

[Copilot]

Pull request overview

Adds a new virtio-console device to OpenVMM that bridges a guest virtio console (/dev/hvc0) to the existing SerialIo backend ecosystem, plus the resource plumbing and CLI/docs wiring needed to instantiate it from openvmm_entry.

Changes:

• Introduce virtio_console crate (device implementation, resolver, spec constants, integration tests).
• Extend virtio queue API with peek/consume support and change VirtioDevice::enable to return anyhow::Result<()>.
• Wire --virtio-console into openvmm_entry, register the resolver, and update the Guide CLI reference.

Reviewed changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
vm/devices/virtio/virtio_resources/src/lib.rs	Adds VirtioConsoleHandle resource type for instantiating the device.
vm/devices/virtio/virtio_console/src/lib.rs	Implements the virtio-console device and async worker loop.
vm/devices/virtio/virtio_console/src/resolver.rs	Adds a resource resolver that constructs the device from a serial backend resource.
vm/devices/virtio/virtio_console/src/spec.rs	Defines virtio-console constants and config layout helper.
vm/devices/virtio/virtio_console/src/tests.rs	Adds integration-style tests driving real virtio rings in guest memory.
vm/devices/virtio/virtio_console/Cargo.toml	New crate manifest and dependencies.
vm/devices/virtio/virtio/src/queue/split.rs	Refactors split-queue availability checks to support peek without consuming.
vm/devices/virtio/virtio/src/queue.rs	Adds core peek/advance APIs (currently split-focused) and refactors work construction.
vm/devices/virtio/virtio/src/common.rs	Adds shared payload read helpers and introduces PeekedWork + VirtioQueue::peek().
openvmm/openvmm_resources/src/lib.rs	Registers the new virtio-console resolver.
openvmm/openvmm_resources/Cargo.toml	Adds dependency on virtio_console.
openvmm/openvmm_entry/src/lib.rs	Instantiates virtio-console via --virtio-console and adds the device to virtio bus.
openvmm/openvmm_entry/src/cli_args.rs	Adds the new --virtio-console CLI flag.
Guide/src/reference/openvmm/management/cli.md	Documents --virtio-console alongside other serial options.
Cargo.toml	Adds virtio_console to workspace members/deps.
Cargo.lock	Locks the new crate and dependency graph updates.

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[jstarks]

Pulled peek changes out to #2992, will rebase once those are in.

[Copilot]

Pull request overview

Adds a new virtio_console device to bridge a guest virtio-console port (/dev/hvc0) to existing SerialIo backends, with supporting virtio API updates and OpenVMM CLI plumbing.

Changes:

• Introduces virtio_console crate (device implementation, resolver, spec constants, and integration tests).
• Extends virtio core APIs (device enable() now returns anyhow::Result<()>; adds queue peek/consume API).
• Wires a new --virtio-console CLI flag and updates the Guide CLI reference.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
vm/devices/virtio/virtio_resources/src/lib.rs	Adds a VirtioConsoleHandle resource definition for the new device.
vm/devices/virtio/virtio_console/src/lib.rs	Implements the virtio-console device + worker loop.
vm/devices/virtio/virtio_console/src/resolver.rs	Adds resource resolver to instantiate VirtioConsoleDevice from resources.
vm/devices/virtio/virtio_console/src/spec.rs	Defines virtio-console device ID, feature bits, and config layout.
vm/devices/virtio/virtio_console/src/tests.rs	Adds integration tests covering RX/TX, large payloads, disconnect/reconnect, and re-enable.
vm/devices/virtio/virtio_console/Cargo.toml	New crate manifest for virtio_console.
vm/devices/virtio/virtio/src/common.rs	Updates virtio device trait docs (and enable() result signature).
openvmm/openvmm_resources/src/lib.rs	Registers the virtio-console resolver.
openvmm/openvmm_resources/Cargo.toml	Adds virtio_console dependency.
openvmm/openvmm_entry/src/lib.rs	Instantiates virtio-console device when --virtio-console is provided.
openvmm/openvmm_entry/src/cli_args.rs	Adds the --virtio-console CLI flag.
Guide/src/reference/openvmm/management/cli.md	Documents the new CLI flag and serial backend usage.
Cargo.toml	Adds virtio_console to workspace dependencies.
Cargo.lock	Adds lockfile entry for virtio_console.

Comments suppressed due to low confidence (1)

Guide/src/reference/openvmm/management/cli.md:53

• The doc says the BACKEND argument is the same for all serial devices, but the list below omits options that are accepted by SerialConfigCli (e.g. file=<path> and term[=<program>][,name=<windowtitle>]). Either expand this list to match the actual accepted values or soften the wording so it doesn’t imply the list is complete.

The `BACKEND` argument is the same for all serial devices:

  * `none`: Serial output is dropped.
  * `console`: Serial input is read and output is written to the console.
  * `stderr`: Serial output is written to stderr.
  * `listen=PATH`: A named pipe (on Windows) or Unix socket (on Linux) is set
      up to listen on the given path. Serial input and output is relayed to this
      pipe/socket.
  * `listen=tcp:IP:PORT`: As with `listen=PATH`, but listen for TCP
      connections on the given IP address and port. Typically IP will be
      127.0.0.1, to restrict connections to the current host.

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[chris-oo]

see comments

[Copilot]

Pull request overview

Adds a new virtio-console device (virtio device ID 3) that bridges a guest console (/dev/hvc0) to an arbitrary SerialIo backend, wiring it into OpenVMM’s resource system and CLI.

Changes:

• Introduces new virtio_console crate with device implementation, resolver, spec constants, and integration tests.
• Adds a new virtio-console resource handle in virtio_resources and registers the resolver in openvmm_resources.
• Adds --virtio-console <BACKEND> CLI flag and updates the OpenVMM Guide CLI reference.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
vm/devices/virtio/virtio_resources/src/lib.rs	Adds VirtioConsoleHandle resource definition for virtio-console devices.
vm/devices/virtio/virtio_console/src/lib.rs	Implements the virtio-console device and worker logic.
vm/devices/virtio/virtio_console/src/spec.rs	Defines virtio-console spec constants and config layout.
vm/devices/virtio/virtio_console/src/resolver.rs	Adds resource resolver to instantiate the device from resources.
vm/devices/virtio/virtio_console/src/tests.rs	Adds integration tests exercising TX/RX, disconnect/reconnect, and re-enable flows.
vm/devices/virtio/virtio_console/Cargo.toml	Declares the new crate and its dependencies.
vm/devices/virtio/virtio/src/common.rs	Updates virtio device trait documentation around enable/disable behavior.
openvmm/openvmm_resources/src/lib.rs	Registers the virtio-console resolver.
openvmm/openvmm_resources/Cargo.toml	Adds virtio_console dependency.
openvmm/openvmm_entry/src/cli_args.rs	Adds --virtio-console CLI option.
openvmm/openvmm_entry/src/lib.rs	Wires CLI flag into VM config by adding the virtio-console device.
Guide/src/reference/openvmm/management/cli.md	Documents the new --virtio-console flag and shared serial backend syntax.
Cargo.toml	Adds virtio_console to workspace members/dependencies.
Cargo.lock	Adds lockfile entries for the new crate.

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[Copilot]

Pull request overview

Adds a new virtio_console device to bridge a guest virtio console (/dev/hvc0) to an existing SerialIo backend, wiring it into resource resolution and the openvmm_entry CLI.

Changes:

• Introduces the virtio_console crate (device, resolver, spec constants, integration tests).
• Registers virtio-console as a virtio resource and resolver, and wires up --virtio-console CLI flag.
• Updates the Guide CLI reference to document --virtio-console.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vm/devices/virtio/virtio_resources/src/lib.rs	Adds a VirtioConsoleHandle resource type for instantiating the device with a serial backend.
vm/devices/virtio/virtio_console/src/lib.rs	Implements the virtio-console device and worker loop (TX/RX, disconnect handling).
vm/devices/virtio/virtio_console/src/spec.rs	Defines virtio-console device/spec constants and config-space layout helper.
vm/devices/virtio/virtio_console/src/resolver.rs	Adds a resource resolver to build the device from a serial backend resource.
vm/devices/virtio/virtio_console/src/tests.rs	Adds integration tests that drive real virtio queues against a mock serial backend.
vm/devices/virtio/virtio_console/Cargo.toml	Adds the new crate’s dependencies and workspace lints.
vm/devices/virtio/virtio/src/common.rs	Updates VirtioDevice docs for enable/disable lifecycle expectations.
openvmm/openvmm_resources/src/lib.rs	Registers the virtio-console resolver.
openvmm/openvmm_resources/Cargo.toml	Adds virtio_console dependency.
openvmm/openvmm_entry/src/lib.rs	Instantiates virtio-console when --virtio-console is provided.
openvmm/openvmm_entry/src/cli_args.rs	Adds --virtio-console CLI option.
Guide/src/reference/openvmm/management/cli.md	Documents the new --virtio-console flag.
Cargo.toml / Cargo.lock	Adds the new crate to the workspace and lockfile.

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