On 9/14/19 1:25 AM, Chris Wilson wrote:
Before we execute a batch, we must first issue any and all TLB invalidations so that batch picks up the new page table entries. Tigerlake's preparser is weakening our post-sync CS_STALL inside the invalidate pipe-control and allowing the loading of the batch buffer before we have setup its page table (and so it loads the wrong page and executes indefinitely). Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> Cc: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com> Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com> --- Suggestions welcome as this does not seem intended behaviour, so I suspect there is a strong pipecontrol flag we are missing.
When I discussed the pre-parser with the HW team the feedback I got was that the only way to make sure we don't race the memory update is to either leave enough CL of space or turn the parser off like you did below. That discussion was about actual physical memory access though and not TLB. Anyway, turning off the parser around the pipe control, if it fixes the problem, shouldn't be too bad since the main performance advantage of the parser is expected inside the user batch. The alternative would probably be to stop invalidating the TLBs from within the ring and switch to MMIO invalidations when lite-restoring a new request in the ring (the CS will implicitly stop the parser and invalidate everything on a full ctx switch).
Daniele
--- drivers/gpu/drm/i915/gt/intel_lrc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index a3f0e4999744..a9e690c303cc 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -2796,11 +2796,14 @@ static int gen11_emit_flush_render(struct i915_request *request, flags |= PIPE_CONTROL_QW_WRITE; flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;- cs = intel_ring_begin(request, 6);+ cs = intel_ring_begin(request, 8); if (IS_ERR(cs)) return PTR_ERR(cs);+ *cs++ = MI_ARB_CHECK | 1 << 8 | 1;cs = gen8_emit_pipe_control(cs, flags, scratch_addr); + *cs++ = MI_ARB_CHECK | 1 << 8; + intel_ring_advance(request, cs); }
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