[PATCH] drm/i915: Fix context/engine cleanup order

[Nick Hoath <nicholas.hoath@intel.com>]

Swap the order of context & engine cleanup, so that it is now
contexts, then engines.
This allows the context clean up code to do things like confirm
that ring->dev->struct_mutex is locked without a NULL pointer
dereference.
This came about as a result of the 'intel_ring_initialized() must
be simple and inline' patch now using ring->dev as an initialised
flag.
Rename the cleanup function to reflect what it actually does.
Also clean up some very annoying whitespace issues at the same time.
Previous code did a kunmap() on the wrong page, and didn't account for
the fact that the HWSP and the default context are the different offsets
within the same object.

v2: Also make the fix in i915_load_modeset_init, not just
    in i915_driver_unload (Chris Wilson)
v3: Folded in Dave Gordon's fix for HWSP kunmap issues.

Signed-off-by: Nick Hoath <nicholas.hoath@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Gordon <david.s.gordon@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_dma.c         |  4 +--
 drivers/gpu/drm/i915/i915_drv.h         |  2 +-
 drivers/gpu/drm/i915/i915_gem.c         | 23 ++++++-------
 drivers/gpu/drm/i915/i915_gem_context.c |  9 ++++--
 drivers/gpu/drm/i915/intel_lrc.c        | 57 +++++++++++++++++++++++----------
 5 files changed, 62 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 84e2b20..4dad121 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -449,8 +449,8 @@ static int i915_load_modeset_init(struct drm_device *dev)
 
 cleanup_gem:
 	mutex_lock(&dev->struct_mutex);
-	i915_gem_cleanup_ringbuffer(dev);
 	i915_gem_context_fini(dev);
+	i915_gem_cleanup_engines(dev);
 	mutex_unlock(&dev->struct_mutex);
 cleanup_irq:
 	intel_guc_ucode_fini(dev);
@@ -1188,8 +1188,8 @@ int i915_driver_unload(struct drm_device *dev)
 
 	intel_guc_ucode_fini(dev);
 	mutex_lock(&dev->struct_mutex);
-	i915_gem_cleanup_ringbuffer(dev);
 	i915_gem_context_fini(dev);
+	i915_gem_cleanup_engines(dev);
 	mutex_unlock(&dev->struct_mutex);
 	intel_fbc_cleanup_cfb(dev_priv);
 	i915_gem_cleanup_stolen(dev);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5edd393..e317f88 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3016,7 +3016,7 @@ int i915_gem_init_rings(struct drm_device *dev);
 int __must_check i915_gem_init_hw(struct drm_device *dev);
 int i915_gem_l3_remap(struct drm_i915_gem_request *req, int slice);
 void i915_gem_init_swizzling(struct drm_device *dev);
-void i915_gem_cleanup_ringbuffer(struct drm_device *dev);
+void i915_gem_cleanup_engines(struct drm_device *dev);
 int __must_check i915_gpu_idle(struct drm_device *dev);
 int __must_check i915_gem_suspend(struct drm_device *dev);
 void __i915_add_request(struct drm_i915_gem_request *req,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 8e2acde..04a22db 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4823,7 +4823,7 @@ i915_gem_init_hw(struct drm_device *dev)
 
 		ret = i915_gem_request_alloc(ring, ring->default_context, &req);
 		if (ret) {
-			i915_gem_cleanup_ringbuffer(dev);
+			i915_gem_cleanup_engines(dev);
 			goto out;
 		}
 
@@ -4836,7 +4836,7 @@ i915_gem_init_hw(struct drm_device *dev)
 		if (ret && ret != -EIO) {
 			DRM_ERROR("PPGTT enable ring #%d failed %d\n", i, ret);
 			i915_gem_request_cancel(req);
-			i915_gem_cleanup_ringbuffer(dev);
+			i915_gem_cleanup_engines(dev);
 			goto out;
 		}
 
@@ -4844,7 +4844,7 @@ i915_gem_init_hw(struct drm_device *dev)
 		if (ret && ret != -EIO) {
 			DRM_ERROR("Context enable ring #%d failed %d\n", i, ret);
 			i915_gem_request_cancel(req);
-			i915_gem_cleanup_ringbuffer(dev);
+			i915_gem_cleanup_engines(dev);
 			goto out;
 		}
 
@@ -4919,7 +4919,7 @@ out_unlock:
 }
 
 void
-i915_gem_cleanup_ringbuffer(struct drm_device *dev)
+i915_gem_cleanup_engines(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_engine_cs *ring;
@@ -4928,13 +4928,14 @@ i915_gem_cleanup_ringbuffer(struct drm_device *dev)
 	for_each_ring(ring, dev_priv, i)
 		dev_priv->gt.cleanup_ring(ring);
 
-    if (i915.enable_execlists)
-            /*
-             * Neither the BIOS, ourselves or any other kernel
-             * expects the system to be in execlists mode on startup,
-             * so we need to reset the GPU back to legacy mode.
-             */
-            intel_gpu_reset(dev);
+	if (i915.enable_execlists) {
+		/*
+		 * Neither the BIOS, ourselves or any other kernel
+		 * expects the system to be in execlists mode on startup,
+		 * so we need to reset the GPU back to legacy mode.
+		 */
+		intel_gpu_reset(dev);
+	}
 }
 
 static void
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 900ffd0..7df3c7a 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -431,17 +431,22 @@ void i915_gem_context_fini(struct drm_device *dev)
 		i915_gem_object_ggtt_unpin(dctx->legacy_hw_ctx.rcs_state);
 	}
 
-	for (i = 0; i < I915_NUM_RINGS; i++) {
+	for (i = I915_NUM_RINGS; --i >= 0;) {
 		struct intel_engine_cs *ring = &dev_priv->ring[i];
 
 		if (ring->last_context)
 			i915_gem_context_unreference(ring->last_context);
 
-		ring->default_context = NULL;
 		ring->last_context = NULL;
 	}
 
 	i915_gem_context_unreference(dctx);
+
+	for (i = I915_NUM_RINGS; --i >= 0;) {
+		struct intel_engine_cs *ring = &dev_priv->ring[i];
+
+		ring->default_context = NULL;
+	}
 }
 
 int i915_gem_context_enable(struct drm_i915_gem_request *req)
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 7644c48..ad12304 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -226,9 +226,8 @@ enum {
 #define CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT  0x17
 
 static int intel_lr_context_pin(struct drm_i915_gem_request *rq);
-static void lrc_setup_hardware_status_page(struct intel_engine_cs *ring,
-		struct drm_i915_gem_object *default_ctx_obj);
-
+static void lrc_setup_hardware_status_page(struct intel_engine_cs *ring);
+static void lrc_teardown_hardware_status_page(struct intel_engine_cs *ring);
 
 /**
  * intel_sanitize_enable_execlists() - sanitize i915.enable_execlists
@@ -1473,8 +1472,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *ring)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u8 next_context_status_buffer_hw;
 
-	lrc_setup_hardware_status_page(ring,
-				ring->default_context->engine[ring->id].state);
+	lrc_setup_hardware_status_page(ring);
 
 	I915_WRITE_IMR(ring, ~(ring->irq_enable_mask | ring->irq_keep_mask));
 	I915_WRITE(RING_HWSTAM(ring->mmio_base), 0xffffffff);
@@ -1905,10 +1903,9 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *ring)
 	i915_cmd_parser_fini_ring(ring);
 	i915_gem_batch_pool_fini(&ring->batch_pool);
 
-	if (ring->status_page.obj) {
-		kunmap(sg_page(ring->status_page.obj->pages->sgl));
-		ring->status_page.obj = NULL;
-	}
+	/* Status page should have gone already */
+	WARN_ON(ring->status_page.page_addr);
+	WARN_ON(ring->status_page.obj);
 
 	lrc_destroy_wa_ctx_obj(ring);
 	ring->dev = NULL;
@@ -2370,7 +2367,7 @@ void intel_lr_context_free(struct intel_context *ctx)
 {
 	int i;
 
-	for (i = 0; i < I915_NUM_RINGS; i++) {
+	for (i = I915_NUM_RINGS; --i >= 0;) {
 		struct drm_i915_gem_object *ctx_obj = ctx->engine[i].state;
 
 		if (ctx_obj) {
@@ -2379,6 +2376,11 @@ void intel_lr_context_free(struct intel_context *ctx)
 			struct intel_engine_cs *ring = ringbuf->ring;
 
 			if (ctx == ring->default_context) {
+				/*
+				 * The HWSP is part of the default context
+				 * object in LRC mode.
+				 */
+				lrc_teardown_hardware_status_page(ring);
 				intel_unpin_ringbuffer_obj(ringbuf);
 				i915_gem_object_ggtt_unpin(ctx_obj);
 			}
@@ -2413,24 +2415,45 @@ static uint32_t get_lr_context_size(struct intel_engine_cs *ring)
 	return ret;
 }
 
-static void lrc_setup_hardware_status_page(struct intel_engine_cs *ring,
-		struct drm_i915_gem_object *default_ctx_obj)
+static void lrc_setup_hardware_status_page(struct intel_engine_cs *ring)
 {
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+	struct intel_context *dctx = ring->default_context;
+	struct drm_i915_gem_object *dctx_obj = dctx->engine[ring->id].state;
+	u64 dctx_addr = i915_gem_obj_ggtt_offset(dctx_obj);
 	struct page *page;
 
-	/* The HWSP is part of the default context object in LRC mode. */
-	ring->status_page.gfx_addr = i915_gem_obj_ggtt_offset(default_ctx_obj)
-			+ LRC_PPHWSP_PN * PAGE_SIZE;
-	page = i915_gem_object_get_page(default_ctx_obj, LRC_PPHWSP_PN);
+	/*
+	 * The HWSP is part of the default context object in LRC mode.
+	 * Note that it doesn't contribute to the refcount!
+	 */
+	page = i915_gem_object_get_page(dctx_obj, LRC_PPHWSP_PN);
 	ring->status_page.page_addr = kmap(page);
-	ring->status_page.obj = default_ctx_obj;
+	ring->status_page.gfx_addr = dctx_addr + LRC_PPHWSP_PN * PAGE_SIZE;
+	ring->status_page.obj = dctx_obj;
 
 	I915_WRITE(RING_HWS_PGA(ring->mmio_base),
 			(u32)ring->status_page.gfx_addr);
 	POSTING_READ(RING_HWS_PGA(ring->mmio_base));
 }
 
+/* This should be called before the default context is destroyed */
+static void lrc_teardown_hardware_status_page(struct intel_engine_cs *ring)
+{
+	struct intel_context *dctx = ring->default_context;
+	struct drm_i915_gem_object *dctx_obj = dctx->engine[ring->id].state;
+	struct page *page;
+
+	if (ring->status_page.page_addr) {
+		page = i915_gem_object_get_page(dctx_obj, LRC_PPHWSP_PN);
+		kunmap(page);
+		ring->status_page.page_addr = NULL;
+	}
+
+	ring->status_page.obj = NULL;
+}
+
+
 /**
  * intel_lr_context_deferred_alloc() - create the LRC specific bits of a context
  * @ctx: LR context to create.
-- 
1.9.1

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