[Intel-gfx] [PATCH] drm/i915: Extend LRC pinning to cover GPU context writeback
Daniel Vetter
daniel at ffwll.ch
Thu Dec 3 01:44:36 PST 2015
On Wed, Dec 02, 2015 at 05:02:07PM -0800, Yu Dai wrote:
> I tested this with GuC submission enabled and it fixes the issue I found
> during GPU reset.
>
> Reviewed-by: Alex Dai <yu.dai at intel.com>
Queued for -next, thanks for the patch.
-Daniel
>
> On 12/01/2015 06:48 AM, Nick Hoath wrote:
> >Use the first retired request on a new context to unpin
> >the old context. This ensures that the hw context remains
> >bound until it has been written back to by the GPU.
> >Now that the context is pinned until later in the request/context
> >lifecycle, it no longer needs to be pinned from context_queue to
> >retire_requests.
> >This fixes an issue with GuC submission where the GPU might not
> >have finished writing back the context before it is unpinned. This
> >results in a GPU hang.
> >
> >v2: Moved the new pin to cover GuC submission (Alex Dai)
> > Moved the new unpin to request_retire to fix coverage leak
> >v3: Added switch to default context if freeing a still pinned
> > context just in case the hw was actually still using it
> >v4: Unwrapped context unpin to allow calling without a request
> >v5: Only create a switch to idle context if the ring doesn't
> > already have a request pending on it (Alex Dai)
> > Rename unsaved to dirty to avoid double negatives (Dave Gordon)
> > Changed _no_req postfix to __ prefix for consistency (Dave Gordon)
> > Split out per engine cleanup from context_free as it
> > was getting unwieldy
> > Corrected locking (Dave Gordon)
> >v6: Removed some bikeshedding (Mika Kuoppala)
> > Added explanation of the GuC hang that this fixes (Daniel Vetter)
> >v7: Removed extra per request pinning from ring reset code (Alex Dai)
> > Added forced ring unpin/clean in error case in context free (Alex Dai)
> >
> >Signed-off-by: Nick Hoath <nicholas.hoath at intel.com>
> >Issue: VIZ-4277
> >Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> >Cc: David Gordon <david.s.gordon at intel.com>
> >Cc: Chris Wilson <chris at chris-wilson.co.uk>
> >Cc: Alex Dai <yu.dai at intel.com>
> >Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> >---
> > drivers/gpu/drm/i915/i915_drv.h | 1 +
> > drivers/gpu/drm/i915/i915_gem.c | 7 +-
> > drivers/gpu/drm/i915/intel_lrc.c | 136 ++++++++++++++++++++++++++++++++-------
> > drivers/gpu/drm/i915/intel_lrc.h | 1 +
> > 4 files changed, 118 insertions(+), 27 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> >index d5cf30b..e82717a 100644
> >--- a/drivers/gpu/drm/i915/i915_drv.h
> >+++ b/drivers/gpu/drm/i915/i915_drv.h
> >@@ -889,6 +889,7 @@ struct intel_context {
> > struct {
> > struct drm_i915_gem_object *state;
> > struct intel_ringbuffer *ringbuf;
> >+ bool dirty;
> > int pin_count;
> > } engine[I915_NUM_RINGS];
> >diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> >index e955499..69e9d96 100644
> >--- a/drivers/gpu/drm/i915/i915_gem.c
> >+++ b/drivers/gpu/drm/i915/i915_gem.c
> >@@ -1354,6 +1354,9 @@ static void i915_gem_request_retire(struct drm_i915_gem_request *request)
> > {
> > trace_i915_gem_request_retire(request);
> >+ if (i915.enable_execlists)
> >+ intel_lr_context_complete_check(request);
> >+
> > /* We know the GPU must have read the request to have
> > * sent us the seqno + interrupt, so use the position
> > * of tail of the request to update the last known position
> >@@ -2765,10 +2768,6 @@ static void i915_gem_reset_ring_cleanup(struct drm_i915_private *dev_priv,
> > struct drm_i915_gem_request,
> > execlist_link);
> > list_del(&submit_req->execlist_link);
> >-
> >- if (submit_req->ctx != ring->default_context)
> >- intel_lr_context_unpin(submit_req);
> >-
> > i915_gem_request_unreference(submit_req);
> > }
> > spin_unlock_irq(&ring->execlist_lock);
> >diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> >index 06180dc..b4d9c8f 100644
> >--- a/drivers/gpu/drm/i915/intel_lrc.c
> >+++ b/drivers/gpu/drm/i915/intel_lrc.c
> >@@ -566,9 +566,6 @@ static int execlists_context_queue(struct drm_i915_gem_request *request)
> > struct drm_i915_gem_request *cursor;
> > int num_elements = 0;
> >- if (request->ctx != ring->default_context)
> >- intel_lr_context_pin(request);
> >-
> > i915_gem_request_reference(request);
> > spin_lock_irq(&ring->execlist_lock);
> >@@ -732,6 +729,13 @@ intel_logical_ring_advance_and_submit(struct drm_i915_gem_request *request)
> > if (intel_ring_stopped(ring))
> > return;
> >+ if (request->ctx != ring->default_context) {
> >+ if (!request->ctx->engine[ring->id].dirty) {
> >+ intel_lr_context_pin(request);
> >+ request->ctx->engine[ring->id].dirty = true;
> >+ }
> >+ }
> >+
> > if (dev_priv->guc.execbuf_client)
> > i915_guc_submit(dev_priv->guc.execbuf_client, request);
> > else
> >@@ -958,12 +962,6 @@ void intel_execlists_retire_requests(struct intel_engine_cs *ring)
> > spin_unlock_irq(&ring->execlist_lock);
> > list_for_each_entry_safe(req, tmp, &retired_list, execlist_link) {
> >- struct intel_context *ctx = req->ctx;
> >- struct drm_i915_gem_object *ctx_obj =
> >- ctx->engine[ring->id].state;
> >-
> >- if (ctx_obj && (ctx != ring->default_context))
> >- intel_lr_context_unpin(req);
> > list_del(&req->execlist_link);
> > i915_gem_request_unreference(req);
> > }
> >@@ -1058,21 +1056,39 @@ reset_pin_count:
> > return ret;
> > }
> >-void intel_lr_context_unpin(struct drm_i915_gem_request *rq)
> >+static void __intel_lr_context_unpin(struct intel_engine_cs *ring,
> >+ struct intel_context *ctx)
> > {
> >- struct intel_engine_cs *ring = rq->ring;
> >- struct drm_i915_gem_object *ctx_obj = rq->ctx->engine[ring->id].state;
> >- struct intel_ringbuffer *ringbuf = rq->ringbuf;
> >-
> >+ struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
> >+ struct intel_ringbuffer *ringbuf = ctx->engine[ring->id].ringbuf;
> > if (ctx_obj) {
> > WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
> >- if (--rq->ctx->engine[ring->id].pin_count == 0) {
> >+ if (--ctx->engine[ring->id].pin_count == 0) {
> > intel_unpin_ringbuffer_obj(ringbuf);
> > i915_gem_object_ggtt_unpin(ctx_obj);
> > }
> > }
> > }
> >+void intel_lr_context_unpin(struct drm_i915_gem_request *rq)
> >+{
> >+ __intel_lr_context_unpin(rq->ring, rq->ctx);
> >+}
> >+
> >+void intel_lr_context_complete_check(struct drm_i915_gem_request *req)
> >+{
> >+ struct intel_engine_cs *ring = req->ring;
> >+
> >+ if (ring->last_context && ring->last_context != req->ctx &&
> >+ ring->last_context->engine[ring->id].dirty) {
> >+ __intel_lr_context_unpin(
> >+ ring,
> >+ ring->last_context);
> >+ ring->last_context->engine[ring->id].dirty = false;
> >+ }
> >+ ring->last_context = req->ctx;
> >+}
> >+
> > static int intel_logical_ring_workarounds_emit(struct drm_i915_gem_request *req)
> > {
> > int ret, i;
> >@@ -2367,6 +2383,76 @@ populate_lr_context(struct intel_context *ctx, struct drm_i915_gem_object *ctx_o
> > }
> > /**
> >+ * intel_lr_context_clean_ring() - clean the ring specific parts of an LRC
> >+ * @ctx: the LR context being freed.
> >+ * @ring: the engine being cleaned
> >+ * @ctx_obj: the hw context being unreferenced
> >+ * @ringbuf: the ringbuf being freed
> >+ *
> >+ * Take care of cleaning up the per-engine backing
> >+ * objects and the logical ringbuffer.
> >+ */
> >+static void
> >+intel_lr_context_clean_ring(struct intel_context *ctx,
> >+ struct intel_engine_cs *ring,
> >+ struct drm_i915_gem_object *ctx_obj,
> >+ struct intel_ringbuffer *ringbuf)
> >+{
> >+ int ret;
> >+
> >+ WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
> >+
> >+ if (ctx == ring->default_context) {
> >+ intel_unpin_ringbuffer_obj(ringbuf);
> >+ i915_gem_object_ggtt_unpin(ctx_obj);
> >+ }
> >+
> >+ if (ctx->engine[ring->id].dirty) {
> >+ struct drm_i915_gem_request *req = NULL;
> >+
> >+ /**
> >+ * If there is already a request pending on
> >+ * this ring, wait for that to complete,
> >+ * otherwise create a switch to idle request
> >+ */
> >+ if (list_empty(&ring->request_list)) {
> >+ int ret;
> >+
> >+ ret = i915_gem_request_alloc(
> >+ ring,
> >+ ring->default_context,
> >+ &req);
> >+ if (!ret)
> >+ i915_add_request(req);
> >+ else
> >+ DRM_DEBUG("Failed to ensure context saved");
> >+ } else {
> >+ req = list_first_entry(
> >+ &ring->request_list,
> >+ typeof(*req), list);
> >+ }
> >+ if (req) {
> >+ ret = i915_wait_request(req);
> >+ if (ret != 0) {
> >+ /**
> >+ * If we get here, there's probably been a ring
> >+ * reset, so we just clean up the dirty flag.&
> >+ * pin count.
> >+ */
> >+ ctx->engine[ring->id].dirty = false;
> >+ __intel_lr_context_unpin(
> >+ ring,
> >+ ctx);
> >+ }
> >+ }
> >+ }
> >+
> >+ WARN_ON(ctx->engine[ring->id].pin_count);
> >+ intel_ringbuffer_free(ringbuf);
> >+ drm_gem_object_unreference(&ctx_obj->base);
> >+}
> >+
> >+/**
> > * intel_lr_context_free() - free the LRC specific bits of a context
> > * @ctx: the LR context to free.
> > *
> >@@ -2378,7 +2464,7 @@ void intel_lr_context_free(struct intel_context *ctx)
> > {
> > int i;
> >- for (i = 0; i < I915_NUM_RINGS; i++) {
> >+ for (i = 0; i < I915_NUM_RINGS; ++i) {
> > struct drm_i915_gem_object *ctx_obj = ctx->engine[i].state;
> > if (ctx_obj) {
> >@@ -2386,13 +2472,10 @@ void intel_lr_context_free(struct intel_context *ctx)
> > ctx->engine[i].ringbuf;
> > struct intel_engine_cs *ring = ringbuf->ring;
> >- if (ctx == ring->default_context) {
> >- intel_unpin_ringbuffer_obj(ringbuf);
> >- i915_gem_object_ggtt_unpin(ctx_obj);
> >- }
> >- WARN_ON(ctx->engine[ring->id].pin_count);
> >- intel_ringbuffer_free(ringbuf);
> >- drm_gem_object_unreference(&ctx_obj->base);
> >+ intel_lr_context_clean_ring(ctx,
> >+ ring,
> >+ ctx_obj,
> >+ ringbuf);
> > }
> > }
> > }
> >@@ -2554,5 +2637,12 @@ void intel_lr_context_reset(struct drm_device *dev,
> > ringbuf->head = 0;
> > ringbuf->tail = 0;
> >+
> >+ if (ctx->engine[ring->id].dirty) {
> >+ __intel_lr_context_unpin(
> >+ ring,
> >+ ctx);
> >+ ctx->engine[ring->id].dirty = false;
> >+ }
> > }
> > }
> >diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
> >index 4e60d54..cbc42b8 100644
> >--- a/drivers/gpu/drm/i915/intel_lrc.h
> >+++ b/drivers/gpu/drm/i915/intel_lrc.h
> >@@ -86,6 +86,7 @@ void intel_lr_context_reset(struct drm_device *dev,
> > struct intel_context *ctx);
> > uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
> > struct intel_engine_cs *ring);
> >+void intel_lr_context_complete_check(struct drm_i915_gem_request *req);
> > /* Execlists */
> > int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists);
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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