netvsp: adding MANA VF keepalive diagnostic traces

[erfrimod]

• Tracing keepalive capabilities
• Tracing network settings save and number of saved MANA devices
• Adding debug traces for VFIO missing saved state
• Tracing keepalive mode, enablement, and saved state prior to NIC creation

[Copilot]

Pull request overview

This PR adds additional diagnostic tracing around MANA VF keepalive and network settings save/restore flows in Underhill (OpenHCL), improving observability during servicing and NIC creation.

Changes:

• Log keepalive mode/enablement, saved-state presence, and DMA client mode prior to Underhill NIC creation.
• Add traces for servicing-state resolution per NIC (including counts of saved MANA devices).
• Improve netvsp/VFIO traces for restore vs. new-device creation and successful keepalive state save, plus add save instrumentation and a saved-count trace.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
openhcl/underhill_core/src/worker.rs	Adds info-level traces for keepalive inputs prior to NIC creation and for resolving servicing saved state per NIC.
openhcl/underhill_core/src/emuplat/netvsp.rs	Adds/extends VFIO device creation/restore traces and logs successful keepalive state save.
openhcl/underhill_core/src/dispatch/mod.rs	Adds servicing-request capability flag traces and instruments/logs network settings save with saved-device counts.

[github-actions]

5 Petri tests failed (2 unstable)

[erfrimod]

Validated on tip:

PreciseTimeStamp	Level	TaskName	Fields
2026-07-14 19:23:24.2848429	4	Event	{"message":"received servicing request from host","correlation_id":"7a74faa3-acdb-4b0d-a955-900815a081d9","timeout_hint_ms":200000,"servicing_deadline":"Instant { tv_sec: 393, tv_nsec: 756744322 }","enable_nvme_keepalive":true,"enable_mana_keepalive":true}
2026-07-14 19:23:24.2876217	4	Span Enter	{"mana_keepalive_mode_enabled":true}
2026-07-14 19:23:24.2884209	4	Event	{"message":"MANA device state successfully saved for keepalive","vtl2_vfid":1095647565,"pci_id":"d186:00:00.0"}
2026-07-14 19:23:24.2884216	4	Span Exit
2026-07-14 19:23:24.2884221	4	Event	{"message":"mana device state saved for keepalive","mana_devices_saved":1}
2026-07-14 19:23:24.4125468	4	Event	{"message":"MANA keepalive: resolved saved state for NIC","pci_id":"d186:00:00.0","instance_id":"414e414d-d186-42f4-b4ac-c96bc0ef6468","has_servicing_mana_state":true,"num_mana_devices":1,"has_nic_servicing_state":true}
2026-07-14 19:23:24.4125634	4	Event	{"message":"checking for MANA VF keepalive prior to creating underhill NIC","pci_id":"d186:00:00.0","instance_id":"414e414d-d186-42f4-b4ac-c96bc0ef6468","keepalive_mode":"EnabledHostAndPrivatePoolPresent","keepalive_enabled":true,"has_saved_mana_state":true,"saved_mana_state_pci_id":"d186:00:00.0","dma_clients_mode":"Split"}