guide: document StorVSP channels and subchannels

[mattkur]

The existing storvsp page mentions subchannels in a bullet point but has no coverage of the negotiation sequence, worker model, CPU affinity, performance tradeoffs, or configuration.

Changes

• New Guide page: devices/vmbus/storvsp_channels.md covering subchannel negotiation (mermaid sequence diagram), the one-worker-per-channel model, CPU affinity and VP targeting, IDE accelerator comparison, subchannel scaling illustrations (0 subs through 64 VPs), poll mode mechanics, the slow-disk head-of-line blocking problem, cooperative executor impact, sidecar behavior, configuration (CLI + OpenHCL VTL2 settings + guest kernel params), Hyper-V behavioral differences, and inspect output.
• Updated storvsp.md with cross-link to the new page.
• Updated storage.md with cross-link from sub-channel allocation mention.
• Updated storage_configuration.md with scsi_sub_channels fixed settings documentation.
• Updated ide.md with new IDE accelerator section explaining the StorVSP-backed VMBus path and why it doesn't support subchannels.
• Added Guide cross-link to storvsp crate-level rustdoc.

Addresses #2954, touches #2955. Can be reviewed independently from the VMBus channels (#2977) and CPU scheduling (#2975) PRs.

[Copilot]

Pull request overview

This PR expands OpenVMM Guide documentation around StorVSP’s VMBus channel/subchannel behavior (negotiation, worker/affinity/perf characteristics, and configuration) and adds cross-links from related storage and IDE docs, plus a rustdoc pointer back to the Guide.

Changes:

• Add a new Guide reference page documenting StorVSP channels/subchannels in depth, including diagrams, perf notes, configuration, and inspect output.
• Cross-link the new page from existing StorVSP, storage pipeline, OpenHCL storage configuration, and IDE documentation.
• Add a crate-level rustdoc link from the storvsp crate to the new Guide page.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
vm/devices/storage/storvsp/src/lib.rs	Adds a rustdoc link to the new Guide page for channel/subchannel details.
Guide/src/reference/emulated/legacy_x86/ide.md	Documents the StorVSP-backed IDE accelerator and links to StorVSP channel/subchannel docs.
Guide/src/reference/devices/vmbus/storvsp_channels.md	New, detailed reference page for StorVSP channels/subchannels (negotiation, workers, affinity, perf, config, inspect).
Guide/src/reference/devices/vmbus/storvsp.md	Adds a cross-link to the new channels/subchannels page.
Guide/src/reference/architecture/openhcl/storage_configuration.md	Documents fixed settings and links to the new StorVSP channels/subchannels page.
Guide/src/reference/architecture/devices/storage.md	Links “sub-channel allocation” text to the new StorVSP channels/subchannels page.
Guide/src/SUMMARY.md	Adds the new page to the Guide navigation under VMBus → storvsp.

[Copilot]

Pull request overview

Adds substantially expanded Guide coverage for StorVSP’s channel/subchannel behavior (negotiation, workers, affinity, performance, and configuration) and links it from related storage docs and rustdoc.

Changes:

• Add a new Guide reference page documenting StorVSP channels/subchannels in depth.
• Cross-link the new page from existing StorVSP/storage/IDE documentation.
• Add a crate-level rustdoc link from storvsp to the corresponding Guide page.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
vm/devices/storage/storvsp/src/lib.rs	Adds rustdoc link to the new Guide page for channels/subchannels context.
Guide/src/reference/emulated/legacy_x86/ide.md	Documents the StorVSP-backed IDE accelerator and links to the new page for subchannel details.
Guide/src/reference/devices/vmbus/storvsp_channels.md	New in-depth reference page on negotiation, worker model, affinity, perf tradeoffs, config, and inspect examples.
Guide/src/reference/devices/vmbus/storvsp.md	Adds a cross-link to the new channels/subchannels page.
Guide/src/reference/architecture/openhcl/storage_configuration.md	Documents fixed settings including scsi_sub_channels and links to the new page.
Guide/src/reference/architecture/devices/storage.md	Links “sub-channel allocation” to the new StorVSP channels/subchannels page.
Guide/src/SUMMARY.md	Adds the new page to the mdBook table of contents under StorVSP.

[Copilot]

Pull request overview

This PR expands the OpenVMM Guide’s StorVSP documentation by adding a dedicated reference page explaining StorVSP’s VMBus channel/subchannel model, how it maps to worker execution and VP targeting, and how to configure/tune it across OpenVMM and OpenHCL.

Changes:

• Adds a new Guide page documenting StorVSP channels/subchannels (negotiation, worker model, CPU affinity, scaling, poll mode, configuration, inspect output).
• Cross-links the new page from existing StorVSP/storage docs and adds an IDE-accelerator (StorVSP-backed) section.
• Adds a crate-level rustdoc link from the storvsp crate to the new Guide documentation.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vm/devices/storage/storvsp/src/lib.rs	Adds rustdoc link pointing readers to the new Guide page for channel/subchannel behavior.
Guide/src/reference/emulated/legacy_x86/ide.md	Documents the StorVSP-backed IDE accelerator and explains why it does not use subchannels.
Guide/src/reference/devices/vmbus/storvsp_channels.md	New in-depth reference page for StorVSP channels/subchannels, including diagrams and configuration guidance.
Guide/src/reference/devices/vmbus/storvsp.md	Adds a link from the StorVSP overview page to the new channels/subchannels page.
Guide/src/reference/architecture/openhcl/storage_configuration.md	Documents scsi_sub_channels in fixed VTL2 settings and links to the new StorVSP channels page.
Guide/src/reference/architecture/devices/storage.md	Links sub-channel allocation mention to the new StorVSP channels page.
Guide/src/SUMMARY.md	Adds the new page to the mdBook navigation under VMBus → storvsp.