drm/i915: Better reset handling for contexts

This patch adds to changes for contexts on reset:
Sets last context to default - this will prevent the context switch
happening after a reset. That switch is not possible because the
rings are hung during reset and context switch requires reset. This
behavior will need to be reworked in the future, but this is what we
want for now.

In the future, we'll also want to reset the guilty context to
uninitialized. We should wait for ARB_Robustness related code to land
for that.

This is somewhat for paranoia.  Because we really don't know what the
GPU was doing when it hung, or the state it was in (mid context write,
for example), later restoring the context is a bad idea. By setting the
flag to not initialized, the next load of that context will not restore
the state, and thus on the subsequent switch away from the context will
overwrite the old data.

NOTE: This code needs a fixup when we actually have multiple VMs. The
issue that can occur is inactive objects in a VM will need to be
destroyed before the last context unref. This can now happen via the
fake switch introduced in this patch (and it other ways in the future)

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2b16c29ea571d0604f685b42b5e97580c0fd7024..40acdde5f224d3f30261c9b9dd1c5421b3475e14 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2225,6 +2225,7 @@ i915_gem_obj_ggtt_pin(struct drm_i915_gem_object *obj,
 /* i915_gem_context.c */
 int __must_check i915_gem_context_init(struct drm_device *dev);
 void i915_gem_context_fini(struct drm_device *dev);
+void i915_gem_context_reset(struct drm_device *dev);
 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
 int i915_switch_context(struct intel_ring_buffer *ring,

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 254f575b259c3808d08e8ace0ac243d3c42154ed..fe17c62c7b092ff0d96378cb82b6e0101024e8ce 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2412,6 +2412,8 @@ void i915_gem_reset(struct drm_device *dev)
 
        i915_gem_cleanup_ringbuffer(dev);
 
+       i915_gem_context_reset(dev);
+
        i915_gem_restore_fences(dev);
 }
 

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 5f8bc06e8594151cbe46ba316b2767f554b08a4d..509e460e982ea5be6cb98ca03d39962d41c9549b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -255,6 +255,49 @@ err_destroy:
        return ret;
 }
 
+void i915_gem_context_reset(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       struct intel_ring_buffer *ring;
+       int i;
+
+       if (!HAS_HW_CONTEXTS(dev))
+               return;
+
+       /* Prevent the hardware from restoring the last context (which hung) on
+        * the next switch */
+       for (i = 0; i < I915_NUM_RINGS; i++) {
+               struct i915_hw_context *dctx;
+               if (!(INTEL_INFO(dev)->ring_mask & (1<<i)))
+                       continue;
+
+               /* Do a fake switch to the default context */
+               ring = &dev_priv->ring[i];
+               dctx = ring->default_context;
+               if (WARN_ON(!dctx))
+                       continue;
+
+               if (!ring->last_context)
+                       continue;
+
+               if (ring->last_context == dctx)
+                       continue;
+
+               if (i == RCS) {
+                       WARN_ON(i915_gem_obj_ggtt_pin(dctx->obj,
+                                                     get_context_alignment(dev),
+                                                     false, false));
+                       /* Fake a finish/inactive */
+                       dctx->obj->base.write_domain = 0;
+                       dctx->obj->active = 0;
+               }
+
+               i915_gem_context_unreference(ring->last_context);
+               i915_gem_context_reference(dctx);
+               ring->last_context = dctx;
+       }
+}
+
 int i915_gem_context_init(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;