Open-IOV vGPU-IO: host-side GSP emulation for unmodified NVIDIA guest drivers https://git.vgpu.io/open-iov.git/atom?h=golden-replay 2026-10-02T15:28:49+00:00 2026-10-02T15:28:49+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T15:28:49+00:00 urn:sha1:c17da06d6cd8b9c69449904637bf37729a962989 - docs/eng-ops.md gains Part II, live physical-backend engineering operations: hard rules, the full module-parameter matrix, the routine supervised cycle and clean-release checklist, the debugfs inventory, how to read gsp-phys-state, a debugging scenario catalogue (CTXNOTVALID/promote wedge, fail-safe WPR2, unload hangs, guest wedges, MMU/PTE and PBDMA faults, relay symptoms), a hazard register (crash causes and debugging side effects), the physical-backend OODA loop, and the work-context map with porting flows - architecture, implementation, operations, orientation, getting-started, portability, ecosystem and reference docs corrected to the current state: CUDA driver-API smoke green, CE-class work forwarding and engine-authored releases plus fault relay in place (default off), GR execution blocked on engine-context validity, the promote wedge and designed locked fail-safe, and P5 wave-2 subsumed - internal-reference cleanup in tracked docs (no analysis-source or local-archive references); historical architecture document bannered - README reading list and STATE-CURRENT frontier refreshed; new pages (runbook, green-eye user guide, porting sequence, porting/packaging notes) linked from the tree Link check: scripts/check-docs-links.py passes (56 files, no broken links). 2026-10-02T10:55:42+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T10:55:42+00:00 urn:sha1:b75e316bd42cc34397e5f66b93f4c85181ad18c8 - new default-off gsp_phys_work_defer_release: a forwarded guest push's releases are recorded and its GPFIFO entry is held (no consume, no GP_GET write, no counter publish/stall) until the work item publishes completion; the service thread then delivers the releases, with a fallback on failure/timeout (500 ms cap enforced every pump pass)/ pause/quiesce/channel-delete - new default-off gsp_phys_work_hw_primary: the software copy is skipped for forwarded ops, so the physical engine authors the data; a once-only software copy runs before the releases on any hardware failure or when the request cannot be queued - release-apply helpers extracted; exactly-once latches; channel-delete and teardown handling; counters and a work_guard state line - live: deferred-release run engaged=75 applied=75 timeouts=0 with the full smoke green; hardware-primary run req=100 ok=100 verify_ok=100 fallback=0 copy_skipped=119 copy_fail=0, smoke ALL OK 64/64 (guest read data the engine authored), with 19 fail-closed inline software fallbacks under single-inflight contention; a range-unregistered run proved the fallback (121 skipped copies, all recovered, smoke green) - defaults off; the software path and all existing guards unchanged 2026-10-02T09:04:44+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T09:04:44+00:00 urn:sha1:6e7bad0791d9ff64531e1d670bfafa59a4c7fb63 - the sema service captures the first eligible copy per push from the software resolver's own operands (the real push shape mixes guest RAM with emulated-VRAM shadow addresses, including physical destinations) - HPA resolution: guest RAM through the shared guest-RAM file page cache, emulated VRAM through the mapping of its kernel shadow - new scratch page-table pool: 16 zeroed page-table pages with their page-directory entries built before any engine access, handing out one whole 128-byte GMMU PTE fetch line per copy pair (16 PTEs, 512 pairs per boot, never reused; a PTE written into an already-fetched line is not observed and there is no invalidate path) - the backend submits the copy on the module-owned channel and verifies the result host-side; every miss falls back to the ladder shadow copy, and the software pump remains authoritative - live (full smoke, both parameters on): req=42 ok=42 verify_ok=42 verify_fail=0 fallback=0, guest payload roundtrip ALL OK 64/64, clean latched release; defaults stay off 2026-10-02T07:31:06+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T07:24:35+00:00 urn:sha1:d2de7bf1d6bb7d0931085f87da6c3013cd7f1aca - file-backed guest RAM (launcher memory-backend-file share=on) and in-kernel GPA->HPA translation through the shared file page cache (read_cache_page + page_to_phys + pfn_valid), opened O_LARGEFILE; new default-off gsp_phys_guest_mem parameter - debugfs gsp-phys-guest-ram (path + gpa/off/size ranges) and gsp-phys-guest-gpa (one pinned GPA per boot); rm-call triggers 6/7 run host->guest and guest->host 4 KiB CE copies; trigger 8 is a PTE self-test through a fresh slot - guest page-table slots are pre-built during ladder stage 3: runtime PTE writes into an already-walked page-table line are not observed without a TLB invalidate - guest RAM layout (q35 4.2, 4 GiB): below-4G GPA == file offset, above-4G offset = GPA - 0x80000000 (2 GiB PCI hole) - tests: tools/test/gpage_test.c guest probe; docs + STATE-CURRENT record the live green (G2H/W2G with semaphore release, guest observed the write, smoke ALL OK 64/64, clean latched release) 2026-10-02T06:13:03+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T06:13:03+00:00 urn:sha1:a9998b380c16ff7e9f6d26953643a3f204735efa 2026-10-02T06:07:55+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T06:07:55+00:00 urn:sha1:fdce9fec4d95e5e7141939d55e333e734122aa6e - STATE-CURRENT snapshot moves to the P3 frontier: the host-freeze latch and readiness gates are validated, the static identity overlay and the read-only control forwarding are landed and live-verified - the physical-backend guest-wiring design is now marked P0-P3 implemented with the P2/P3 acceptance results 2026-10-02T00:58:32+00:00 Arthur Hanson Rasmusson arthur@vgpu.io 2026-10-02T00:58:32+00:00 urn:sha1:684dbe2e5c01b7f27e6fe15242b318057454ac5a - STATE-CURRENT snapshot 2026-10-01 21:05: the host RM-client ladder now allocates VAS+PDB+TSG+channel and executes a real 4 KiB VA-mode CE copy (semaphore released, dst==src) on the physical engine; next is wiring the live session into the guest-facing mdev/vfio path. - docs/03-architecture/11-physical-backend-guest-wiring.md: phased design (P0-P6) for bridging the physical backend into the guest-facing emulation, with the seam table, lifecycle changes and static-config flow. - docs/README.md: reading order updated for the new document; execution status refreshed.