drm/i915: Simplify testing for am-I-the-kernel-context?

The kernel context (dev_priv->kernel_context) is unique in that it is
not associated with any user filp - it is the only one with
ctx->file_priv == NULL. This is a simpler test than comparing it against
dev_priv->kernel_context which involves some pointer dancing.

In checking that this is true, we notice that the gvt context is
allocating itself a i915_hw_ppgtt it doesn't use and not flagging that
its file_priv should be invalid.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170106152013.24684-5-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e604672..f671d05 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4230,7 +4230,7 @@ static void assert_kernel_context_is_current(struct drm_i915_private *dev_priv)
        enum intel_engine_id id;
 
        for_each_engine(engine, dev_priv, id)
-               GEM_BUG_ON(engine->last_retired_context != dev_priv->kernel_context);
+               GEM_BUG_ON(!i915_gem_context_is_kernel(engine->last_retired_context));
 }
 
 int i915_gem_suspend(struct drm_i915_private *dev_priv)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 07ac811..40a6939 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -413,14 +413,17 @@ i915_gem_context_create_gvt(struct drm_device *dev)
        if (ret)
                return ERR_PTR(ret);
 
-       ctx = i915_gem_create_context(to_i915(dev), NULL);
+       ctx = __create_hw_context(to_i915(dev), NULL);
        if (IS_ERR(ctx))
                goto out;
 
+       ctx->file_priv = ERR_PTR(-EBADF);
        i915_gem_context_set_closed(ctx); /* not user accessible */
        i915_gem_context_clear_bannable(ctx);
        i915_gem_context_set_force_single_submission(ctx);
        ctx->ring_size = 512 * PAGE_SIZE; /* Max ring buffer size */
+
+       GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
 out:
        mutex_unlock(&dev->struct_mutex);
        return ctx;
@@ -472,6 +475,8 @@ int i915_gem_context_init(struct drm_i915_private *dev_priv)
        ctx->priority = I915_PRIORITY_MIN; /* lowest priority; idle task */
        dev_priv->kernel_context = ctx;
 
+       GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));
+
        DRM_DEBUG_DRIVER("%s context support initialized\n",
                        i915.enable_execlists ? "LR" :
                        dev_priv->hw_context_size ? "HW" : "fake");
@@ -524,6 +529,8 @@ void i915_gem_context_fini(struct drm_i915_private *dev_priv)
 
        lockdep_assert_held(&dev_priv->drm.struct_mutex);
 
+       GEM_BUG_ON(!i915_gem_context_is_kernel(dctx));
+
        context_close(dctx);
        dev_priv->kernel_context = NULL;
 
@@ -549,6 +556,8 @@ int i915_gem_context_open(struct drm_device *dev, struct drm_file *file)
        ctx = i915_gem_create_context(to_i915(dev), file_priv);
        mutex_unlock(&dev->struct_mutex);
 
+       GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
+
        if (IS_ERR(ctx)) {
                idr_destroy(&file_priv->context_idr);
                return PTR_ERR(ctx);
@@ -968,6 +977,8 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
        if (IS_ERR(ctx))
                return PTR_ERR(ctx);
 
+       GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
+
        args->ctx_id = ctx->user_handle;
        DRM_DEBUG("HW context %d created\n", args->ctx_id);
 

diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index 89f6764..0ac750b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -246,6 +246,11 @@ static inline bool i915_gem_context_is_default(const struct i915_gem_context *c)
        return c->user_handle == DEFAULT_CONTEXT_HANDLE;
 }
 
+static inline bool i915_gem_context_is_kernel(struct i915_gem_context *ctx)
+{
+       return !ctx->file_priv;
+}
+
 /* i915_gem_context.c */
 int __must_check i915_gem_context_init(struct drm_i915_private *dev_priv);
 void i915_gem_context_lost(struct drm_i915_private *dev_priv);

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index a9eefb1..6db246a 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -786,7 +786,7 @@ static int execlists_context_pin(struct intel_engine_cs *engine,
        flags = PIN_GLOBAL;
        if (ctx->ggtt_offset_bias)
                flags |= PIN_OFFSET_BIAS | ctx->ggtt_offset_bias;
-       if (ctx == ctx->i915->kernel_context)
+       if (i915_gem_context_is_kernel(ctx))
                flags |= PIN_HIGH;
 
        ret = i915_vma_pin(ce->state, 0, GEN8_LR_CONTEXT_ALIGN, flags);

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index e84d488..0971ac3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1974,7 +1974,7 @@ static int intel_ring_context_pin(struct intel_engine_cs *engine,
                unsigned int flags;
 
                flags = 0;
-               if (ctx == ctx->i915->kernel_context)
+               if (i915_gem_context_is_kernel(ctx))
                        flags = PIN_HIGH;
 
                ret = context_pin(ctx, flags);
@@ -1989,7 +1989,7 @@ static int intel_ring_context_pin(struct intel_engine_cs *engine,
         * as during eviction we cannot allocate and pin the renderstate in
         * order to initialise the context.
         */
-       if (ctx == ctx->i915->kernel_context)
+       if (i915_gem_context_is_kernel(ctx))
                ce->initialised = true;
 
        i915_gem_context_get(ctx);