open-iov.git/kernel/gsp_phys_gpu.h, branch stallfree

vgsp: bounded GR launch completion (GR-STALL), r220 hold storm fix, churn caps

2026-10-18T16:10:03+00:00

Every GR launch now either completes or fails fast with a distinguishable dmesg line; no host wait in the launch/consume path can run forever. - gsp_phys_gr_wait_max_ms (new param, default 60000, clamp [10000,600000], 0 = built-in per-ladder bounds only): absolute per-launch submit budget. Checked in the GR poll loop (after the release acks) and in the retirement-retry loop; on expiry the submit fails out ('vgsp-gr: GR-STALL-wait-max ... action=fail') or the retry loop stops ('GR-STALL-retry ... action=proceed'), so the chain of individually bounded ladder phases can no longer hold the single-inflight work item (and the client's launch wait) for the ladder sum. - gsp_sema_service: pass-top svc_fwd_outcome_check() completes a forwarded GR request that no hold owns. A GR push with no push-level release records engages no release hold, so a backend failure (ladder timeout, abort) left the QMD completion word unwritten and the client waited to its own timeout (r219/r222, qmd_rel frozen at the previous value). The check authors the word in software (full resolver, forward-only, latched once) and logs 'GR-STALL-backend ... action=proceed'. It also covers a *successful* submit whose release0 could not target the guest page (engine completion landed on the module semaphore only) - the work item records gr_rel_unobserved for that. - Consume tail: a GR capture consumed without ever being forwarded (a data-stall / busy-defer / no-capture hold fell through) now authors its QMD completion release, latched per capture, and logs 'GR-STALL-hold'. - r220 hold-storm fix (196 s re-hold): the m150/m156 data-stall hold window is keyed to the GPFIFO slot index, and a pin-batch rewind replays the same launch at different slots, so the window re-armed on every pass; the absolute per-launch backstop could never fire because its record fields were excluded from the pump snapshot write-back list (the GRFIX NOTE record leak) and the fill gate defaulted off. The four bound fields are now written back and svc_gr_hold_bound_expired is effective on the default path (cap gsp_phys_gr_hold_max_ms, default 3000 ms, keyed to the launch push VA via svc_gr_launch_va so nothing re-arms it across rewinds); the busy-defer hold site consults the same bound. On expiry the entry is consumed with the software completion and logs 'GR-STALL-hold-bound'. - Hold expiry/failure edges log 'GR-STALL-fwd-hold' / 'GR-STALL-fwd-fail' with waited_ms for held forwarded launches. - Anti-degradation under pin churn/leftover clients: svc_rescue_scan_range (up to 6 GB of guest-RAM reads on the service thread) is capped at 3 s per range with RESCUE-SCAN-CAP logging; the ledger eviction burst triggers a logged wholesale cache reset (LEDGER-RESET cap-and-degrade, 256 evictions); pending-ring overflow is counted and surfaced (PENDING-OVF, pend_ovf in the drain line). New diag tokens: gr_swrel/pend_ovf, ledger resets, rescue scan_capped, work_gr stall_wait_max/stall_retry/wait_max_ms. Green behavior: normal launches complete in ~0.2-11 s and never approach the budget; the hold bound only fires where the old path could stall forever. make kernel green; only pre-existing warnings. (cherry picked from commit dc3650105f163631bb826ae3685a7d6e9025bfe8)

vgsp: m91 - first-fault capture + QMD instruction-cache invalidate for the SM I-fetch lottery

2026-10-18T16:10:03+00:00

m91-class recap: the first attempt of a mid-sequence forwarded GR launch raises SM warp exceptions ("Illegal Instruction Encoding", "Out Of Range Register") on garbage instruction bytes while a retry of the IDENTICAL QMD and identical shadow content succeeds (r219: fault at +2.5 s, fast re-arm recovered 3 ms later; r223 same pattern). The host retry path only replays the mode-35 lane-enable tail + channel/TSG schedules + doorbell and re-publishes the same method block on a fresh ring entry: no shadow re-copy, no QMD re-read, no cache/TLB invalidate exists anywhere in the ladder. Plain re-submission of byte-identical content flipping the outcome names stale engine-side fetch state at first dispatch, not a content or programming error: the window-0 shadow pool alternates two 8-page banks by submit epoch, so a program VA's bytes change every two launches, and every captured guest QMD carries the QMD v2.3 cache-control word (word 5) with INVALIDATE_INSTRUCTION_CACHE (bit 30) clear - the client driver arms that bit only under its forced-invalidate mode. Two changes: 1. FAULT-CAP (diagnostic, inert until a fault): when a forwarded launch's fault epoch advanced across its window, emit one "vgsp-m91: FAULT-CAP" line per launch (capped at 20 per module-load cycle, then one suppression notice) with: fault-epoch delta, QMD address + first 64 B, live program pair (w48/w49) + resolved engine-visible VA/PA, the first 64 B at that code address, retry decision (fast re-arm / resched/fresh-entry / none) + outcome (ok vs timeout), and the newest relay-decoded 0x1006 note (exceptType/chid/errString). A fault-free launch costs one epoch read and one compare (greens unaffected statically: no prints, no content reads, no engine access). 2. QMD icache invalidate (fix, param-gated default-on gsp_phys_gr_icache_inv=1): set QMD v2.3 word 5 bit 30 in the forwarded QMD (forcing an instruction refetch at dispatch) only when the QMD carries the client driver's standard cache-control signature (word 5 bits 26..29 set) so an unknown QMD revision is never touched; 0 restores the exact pre-change QMD for a one-flip A/B. The bit cannot alter instruction bytes or data - it only invalidates cached fetch state (the same field the client driver sets under forced invalidate) - so green launches keep their semantics; the only cost is a per-launch refetch. Expected next-cycle evidence: zero FAULT-CAP lines with the multi-page client set green confirms the stale-fetch mechanism; any FAULT-CAP content policies the remaining candidates (shadow-VA reuse distance, cross-cycle context state left by killed clients). Doc: 03-architecture/13-vexecution- plane.md m91-class section. (cherry picked from commit 682a5559b1dbbd482d8fe6bdabbc46220ce0d5de)

vgsp: m179 GR no-write robustness - dedicated re-execution budget + specific zero-write test + loud classified accept

2026-10-18T04:26:02+00:00

The r200-r202 memcpy_roundtrip/multikernel all-wrong class: a forwarded GR launch retires with zero tracked engine writes (NOWRITE, qmd_rel satisfied), the m153 outcome-retry loop either never ran (it shared the timeout ladder's attempt counter, which the fast re-arm / fresh entries had already consumed) or exhausted, and the accept path silently restored the release words, handing the client an all-wrong output with a fabricated completion. Changes (kernel/gsp_phys_booter.c, gsp_phys_gpu.c, gsp_phys_gpu.h): 1. gsp_phys_gr_nowrite_retries (default 3, clamped [0,4]): the no-write re-execution loop now has a DEDICATED budget, independent of the timeout ladder's attempts. Each retry keeps the existing backoff mechanics (zero release words, fresh qmdwin/win0 bank, refill bounce, rebuild PB, re-publish + resched, fresh-ack poll, fetch witness, retire wait). Worst case stays within the 8-entry GPFIFO ring (initial + fast re-arm + 2 fresh entries + 3 retries = 7 publishes). 2. Specific zero-write test: gsp_phys_gr_output_retire_wait() now reports n_tracked (the number of data entries that resolve to a bounce page); the no-write retry/accept path only triggers when n_tracked > 0, so a launch whose data entries resolve nothing can no longer false-positive as a lost launch. 3. The accept (last resort after the budget) is now LOUD (pr_warn) and classified by the QMD fetch sentinel: NOWRITE-CONFIRMED = deposit never reached the engine (sweep/hold-faked-ack class); NOWRITE-AMBIGUOUS = engine consumed the deposit, zero tracked writes may be a legitimately read-only kernel. It also runs when the retry master gate is off, so a zero-write outcome is never silent. 4. Ordering: explicit wmb() after the retry's fresh qmdwin deposit (the first-attempt path and the publish tail already carry the barriers; dma_wmb before GP_PUT advance + wmb before the doorbell in gsp_phys_rmcall_publish_locked) - deposit->kick order is now explicit on both paths. 5. Frame bound: the ~370-byte struct gsp_phys_fault_info moved to static scratch (the function's documented single-inflight contract, same as methods[]/qmd[]) with a per-submission memset; this clears the pre-existing >1024-byte frame warning in the submit function instead of growing it. Fast re-arm (gsp_phys_gr_retry_fast) and the timeout ladder are untouched. Build: make kernel -j - green, vgsp.ko; no warnings in touched code.

vgsp: m178 GR launch reliability + diagnostics; tools: pin latching robustness

2026-10-17T23:18:50+00:00

Kernel: authorship instrumentation + swrel gate for in-flight GR release VAs; first-poll shortening + fast extended re-arm (params gr_retry_fast=1, gr_first_poll_ms=2500); per-attempt win0 bank recompute + shadow recopy in the outcome-retry loop; poll-break/deposit-readback diagnostics; C1-C10 sema diagnostics (crel-entry, relx, opdef-clear, walk, pub-adv, hold-fallback, busy-defer, CAND-OVERWRITE, inline recs); busy-defer hold instead of software-release consume; counter fast path; QMD word 48/49 skip. Tools: heartbeat thread, scanner-alive probe on reinstall, full periodic re-assert, #nopid handling, per-client reset fix (debounce), dead-pid drop, supervisor grace+threshold.

Merge branch 'dual'

2026-10-16T17:33:02+00:00

vgsp-dual: stage B+C minimal per-mdev separation (G1-G3, G5, G6, G7, G8a)

2026-10-15T21:53:52+00:00

Goal 1.0: two mdevs + two QEMU guests running CUDA simultaneously. Single-mdev behaviour is kept identical: the legacy guest-RAM record still serves the first/only open mdev, the channel table degenerates to the historical key, and the session flush fires at the same last-channel-closed transition. - G6: guest-RAM backing {file, path, ranges} per mdev (legacy record + up to 4 vgpu-bound records); debugfs gsp-phys-guest-ram accepts an mdev UUID as an extra first token and keeps the 4-token form; records released on mdev cleanup and physical release. - G7: gsp_phys_gpa_to_hpa_vgpu(vgpu, gpa, *hpa); NULL keeps the historical first-open resolution. Forwarding operands pass the request's vgpu; the single-guest boot-ladder pin passes NULL. - G1: the sema-service thread services every open mdev each pass. - G2: channel table keyed by (vgpu, h_object); per-guest ranks; counter/scrub/opdef/pump snapshot+writeback matches per vgpu; scrubber records per guest. - G3: per-guest session records drive the flush; the shared learned tables (staged G4) are only flushed when no guest has live channels. - G5: hold/abort keyed by (vgpu, handle); dead-owner guards on the hold resolution paths; single-inflight serialization kept. - G8a: guest-GPA pin refused while more than one mdev is open. Build: make -j8 clean success (vgsp.ko). No module load. See DUAL-REPORT.md for the per-item status and live-validation plan.

vgsp-gr: B-2 planted 64 MiB data-bounce region for large GR operands

2026-10-15T21:51:17+00:00

Replace the 205-page / 68-pages-per-pointer GR operand window with a boot-planted 16384-page (64 MiB) region at VA 0x0a000000 (PD0 80..111): one dual PD0 entry per 2 MB window backed by one fresh 4 KB PT page, every leaf PTE written at stage 3 before any engine fetch (the GMMU has no PTE invalidate, so no leaf is rewritten at runtime). The 208-page window, mail slot 206 and marker 207 stay as-is (mail injection and copy diagnostics unchanged) but carry no operand data when the grown region is on. Sema service: reloc base and page cap derive from the shared header constants; per-pointer span becomes a 4096-page runaway guard; a total cap hit is fail-closed (launch stalled for the bounded hold, loud CAP-HIT log, no silent truncation); the launch's own param/bank pages are skipped as data candidates (budget hygiene). Copy-in, copy-out, retirement wait and the window diagnostic index the active region through one helper/chunk selector; checksum and dedup scratch move off the kernel stack. gsp_phys_gr_data_region=0 (insmod, boot-fixed) flips the whole path back to the legacy 205-page window for A/B trialing.

vgsp-gr: m152 scratch-PT alias cache + extended pool; m153 outcome-verifying launch retry

2026-10-15T14:20:13+00:00

m152: the Tier-2 shadow alias pool consumed one never-reused 128 B fetch line per mapping per launch (512 lines/boot), so a normal launch mix exhausted it permanently: every later launch that needed a new mapping was refused (the deterministic r152 'launch refused: no Tier-1 mapping' loop). Two fixes: (a) an HPA-keyed alias cache in map_shadow_locked that returns the existing never-rewritten VA for a page already mapped, so repeat launches of the same buffers/sem pages consume nothing; a hit reports line_out = ~0 so contiguity bookkeeping never extends an old line; (b) a 48-window extension pool at VA 0x04000000 (PD0 indices 32..79, one 48-page PT chunk) raising capacity to 2048 lines/boot. m153: the intermittent per-boot mis-execution classes (engine wrote nothing; or wrote into a lower operand window while the output operand stayed untouched - both complete with qmd_rel/ch_rel satisfied, live evidence in r152 smiley: passes wrote b into the a window / nothing / correct-after-10s-retry) are now detected by the m151 retirement wait and retried: refill the bounce window from the guest inputs, re-publish the same method block on a fresh ring entry, re-issue schedule, re-poll, re-wait - bounded by the timeout path's attempt budget. Gate param gsp_phys_rmcall_gr_nowrite_retry (default 1).

vgsp: m113 - re-register the VAS page directory after planting data (re-commit probe)

2026-10-07T19:33:31+00:00

All late engine-tree writes are invisible to the SM walker (only the commit-time snapshot resolves); the mail injection at a main-window fresh slot also fails (m112). Probe whether UNSET+SET_PAGE_DIRECTORY on the ladder VAS after planting forces the server walker to re-snapshot the tree; gated by gr_recommit.

vgsp: m106 - pre-install the data PT window pool in stage 3 (pre-commit)

2026-10-07T19:05:08+00:00

Post-commit UPDATE_PDE_2 installs are accepted (status 0x0) but ineffective (m94's scratch windows, m101-m105's reloc windows: the SM never resolves them), while the stage-3 ctx-window installs are honoured. Add a fixed 32-window pool at GSP_PHYS_RMCALL_VA_GR_DATA_BASE (0x100000000 + k<<21, inside the server-managed region), each backed by a module PT page installed through UPDATE_PDE_2 during stage 3; the engine data map then only writes leaf PTEs into those fresh PT pages at launch (the P6b-proven 'direct leaf write into a walker-installed fresh table' pattern). The mail injection uses the reserved last window (k=31); service data windows cap at 31 and use the same fixed layout.