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From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>,
	Mika Kuoppala <mika.kuoppala@intel.com>,
	"# v4 . 10+" <stable@vger.kernel.org>
Subject: [PATCH 1/2] drm/i915/execlists: Wrap tail pointer after reset tweaking
Date: Mon, 27 Mar 2017 04:28:14 +0100	[thread overview]
Message-ID: <20170327032815.19504-1-chris@chris-wilson.co.uk> (raw)

If the request->wa_tail is 0 (because it landed exactly on the end of
the ringbuffer), when we reconstruct request->tail following a reset we
fill in an illegal value (-8 or 0x001ffff8). As a result, RING_HEAD is
never able to catch up with RING_TAIL and the GPU spins endlessly. If
the ring contains a couple of breadcrumbs, even our hangcheck is unable
to catch the busy-looping as the ACTHD and seqno continually advance.

Fixes: a3aabe86a340 ("drm/i915/execlists: Reinitialise context image after GPU hang")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: <stable@vger.kernel.org> # v4.10+
---
 drivers/gpu/drm/i915/intel_lrc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 3fdabba0a32d..c8dd848d2ebe 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1302,6 +1302,7 @@ static void reset_common_ring(struct intel_engine_cs *engine,
 
 	/* Reset WaIdleLiteRestore:bdw,skl as well */
 	request->tail = request->wa_tail - WA_TAIL_DWORDS * sizeof(u32);
+	request->tail &= request->ring->size - 1;
 	GEM_BUG_ON(!IS_ALIGNED(request->tail, 8));
 }
 
-- 
2.11.0

WARNING: multiple messages have this Message-ID (diff)
From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Cc: Mika Kuoppala <mika.kuoppala@intel.com>,
	"# v4 . 10+" <stable@vger.kernel.org>
Subject: [PATCH 1/2] drm/i915/execlists: Wrap tail pointer after reset tweaking
Date: Mon, 27 Mar 2017 04:28:14 +0100	[thread overview]
Message-ID: <20170327032815.19504-1-chris@chris-wilson.co.uk> (raw)

If the request->wa_tail is 0 (because it landed exactly on the end of
the ringbuffer), when we reconstruct request->tail following a reset we
fill in an illegal value (-8 or 0x001ffff8). As a result, RING_HEAD is
never able to catch up with RING_TAIL and the GPU spins endlessly. If
the ring contains a couple of breadcrumbs, even our hangcheck is unable
to catch the busy-looping as the ACTHD and seqno continually advance.

Fixes: a3aabe86a340 ("drm/i915/execlists: Reinitialise context image after GPU hang")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: <stable@vger.kernel.org> # v4.10+
---
 drivers/gpu/drm/i915/intel_lrc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 3fdabba0a32d..c8dd848d2ebe 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1302,6 +1302,7 @@ static void reset_common_ring(struct intel_engine_cs *engine,
 
 	/* Reset WaIdleLiteRestore:bdw,skl as well */
 	request->tail = request->wa_tail - WA_TAIL_DWORDS * sizeof(u32);
+	request->tail &= request->ring->size - 1;
 	GEM_BUG_ON(!IS_ALIGNED(request->tail, 8));
 }
 
-- 
2.11.0

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             reply	other threads:[~2017-03-27  3:28 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-27  3:28 Chris Wilson [this message]
2017-03-27  3:28 ` [PATCH 1/2] drm/i915/execlists: Wrap tail pointer after reset tweaking Chris Wilson
2017-03-27  3:28 ` [PATCH 2/2] drm/i915: Assert that the request->tail fits within the ring Chris Wilson
2017-03-27  3:45 ` ✓ Fi.CI.BAT: success for series starting with [1/2] drm/i915/execlists: Wrap tail pointer after reset tweaking Patchwork
2017-03-27 10:44 ` [Intel-gfx] [PATCH 1/2] " Mika Kuoppala
2017-03-27 10:44   ` Mika Kuoppala
2017-03-27 11:00   ` [Intel-gfx] " Chris Wilson
2017-03-27 11:00     ` Chris Wilson
2017-03-27 11:07     ` [Intel-gfx] " Mika Kuoppala
2017-03-27 11:07       ` Mika Kuoppala
2017-03-27 11:19       ` [Intel-gfx] " Chris Wilson
2017-03-27 11:19         ` Chris Wilson

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