On Mon, Aug 24, 2026 at 12:30 PM Denis Pisarev <[email protected]> wrote: > > Hi, > > v3 addresses the two findings from the sashiko-bot review of v2. > Failure data and trigger isolation are unchanged (bugzilla 219492): > S4 resume on Cezanne (gmc_v9, GFXOFF) wedges KIQ TLB flushes at > 80-140/hour for 9+ hours with sched.ready true throughout; holding > GFXOFF off across the S4 cycle produces zero errors. > > 1. [High] "VFs and interrupt contexts silently drop TLB flushes once > the threshold is reached" - correct, and fixed. In v3 the latch > only reroutes bare metal process context to MMIO. VFs and IRQ > contexts keep submitting to KIQ exactly as before this patch, with > per-failure logging, because they have no MMIO alternative; there > is no longer any code path that drops a flush without attempting > and logging. > > 2. [High] "KIQ and MMIO race on the same invalidation engine if KIQ > recovers" - this remains the documented open question; no code > change in v3. Our analysis: once latched, this path submits no new > KIQ commands, so the exposure is limited to already-queued stale > commands and the recovery transition window. The engine serializes > requests internally, so the realistic worst case is a lost flush > request caught by the existing ACK timeout ("Timeout waiting for VM > flush ACK!"), not silent state corruption. If maintainers consider > a fence necessary (or a dedicated invalidate engine for the MMIO > path), guidance on the preferred mechanism would be welcome. > > Full patch history: v1 (initial fallback+counter), v2 (GFXOFF hold, > per-instance counter, irqsave, VF/IRQ restrictions, MES error > propagation) - all from bot review; v3 (this one) fixes the VF/IRQ > drop regression the bot found in v2. > > Also still open from the cover letters: the alternative direction of > fixing the S4 resume ordering itself (RLC/ME vs GFXOFF) instead of a > runtime fallback. Happy to run tracing on the affected hardware. >
If that's a problem, that should be fixed. That said, did you have any success with the branch I proposed? Alex > Patch 1/1 follows. > > Denis Pisarev > > Denis Pisarev (1): > drm/amdgpu: fall back to MMIO TLB invalidation when KIQ is > unresponsive > > drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 + > drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h | 2 + > drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 18 ++-- > drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h | 2 +- > drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 123 +++++++++++++++++++----- > 5 files changed, 114 insertions(+), 33 deletions(-) > > -- > 2.55.0 >
