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Diffstat (limited to 'drivers/gpu/drm/i915/gem/i915_gem_busy.c')
-rw-r--r--drivers/gpu/drm/i915/gem/i915_gem_busy.c139
1 files changed, 139 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
new file mode 100644
index 000000000000..6ad93a09968c
--- /dev/null
+++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
@@ -0,0 +1,139 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2014-2016 Intel Corporation
+ */
+
+#include "gt/intel_engine.h"
+
+#include "i915_gem_ioctls.h"
+#include "i915_gem_object.h"
+
+static __always_inline u32 __busy_read_flag(u8 id)
+{
+ if (id == (u8)I915_ENGINE_CLASS_INVALID)
+ return 0xffff0000u;
+
+ GEM_BUG_ON(id >= 16);
+ return 0x10000u << id;
+}
+
+static __always_inline u32 __busy_write_id(u8 id)
+{
+ /*
+ * The uABI guarantees an active writer is also amongst the read
+ * engines. This would be true if we accessed the activity tracking
+ * under the lock, but as we perform the lookup of the object and
+ * its activity locklessly we can not guarantee that the last_write
+ * being active implies that we have set the same engine flag from
+ * last_read - hence we always set both read and write busy for
+ * last_write.
+ */
+ if (id == (u8)I915_ENGINE_CLASS_INVALID)
+ return 0xffffffffu;
+
+ return (id + 1) | __busy_read_flag(id);
+}
+
+static __always_inline unsigned int
+__busy_set_if_active(const struct dma_fence *fence, u32 (*flag)(u8 id))
+{
+ const struct i915_request *rq;
+
+ /*
+ * We have to check the current hw status of the fence as the uABI
+ * guarantees forward progress. We could rely on the idle worker
+ * to eventually flush us, but to minimise latency just ask the
+ * hardware.
+ *
+ * Note we only report on the status of native fences.
+ */
+ if (!dma_fence_is_i915(fence))
+ return 0;
+
+ /* opencode to_request() in order to avoid const warnings */
+ rq = container_of(fence, const struct i915_request, fence);
+ if (i915_request_completed(rq))
+ return 0;
+
+ /* Beware type-expansion follies! */
+ BUILD_BUG_ON(!typecheck(u8, rq->engine->uabi_class));
+ return flag(rq->engine->uabi_class);
+}
+
+static __always_inline unsigned int
+busy_check_reader(const struct dma_fence *fence)
+{
+ return __busy_set_if_active(fence, __busy_read_flag);
+}
+
+static __always_inline unsigned int
+busy_check_writer(const struct dma_fence *fence)
+{
+ if (!fence)
+ return 0;
+
+ return __busy_set_if_active(fence, __busy_write_id);
+}
+
+int
+i915_gem_busy_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *file)
+{
+ struct drm_i915_gem_busy *args = data;
+ struct drm_i915_gem_object *obj;
+ struct reservation_object_list *list;
+ unsigned int seq;
+ int err;
+
+ err = -ENOENT;
+ rcu_read_lock();
+ obj = i915_gem_object_lookup_rcu(file, args->handle);
+ if (!obj)
+ goto out;
+
+ /*
+ * A discrepancy here is that we do not report the status of
+ * non-i915 fences, i.e. even though we may report the object as idle,
+ * a call to set-domain may still stall waiting for foreign rendering.
+ * This also means that wait-ioctl may report an object as busy,
+ * where busy-ioctl considers it idle.
+ *
+ * We trade the ability to warn of foreign fences to report on which
+ * i915 engines are active for the object.
+ *
+ * Alternatively, we can trade that extra information on read/write
+ * activity with
+ * args->busy =
+ * !reservation_object_test_signaled_rcu(obj->resv, true);
+ * to report the overall busyness. This is what the wait-ioctl does.
+ *
+ */
+retry:
+ seq = raw_read_seqcount(&obj->base.resv->seq);
+
+ /* Translate the exclusive fence to the READ *and* WRITE engine */
+ args->busy =
+ busy_check_writer(rcu_dereference(obj->base.resv->fence_excl));
+
+ /* Translate shared fences to READ set of engines */
+ list = rcu_dereference(obj->base.resv->fence);
+ if (list) {
+ unsigned int shared_count = list->shared_count, i;
+
+ for (i = 0; i < shared_count; ++i) {
+ struct dma_fence *fence =
+ rcu_dereference(list->shared[i]);
+
+ args->busy |= busy_check_reader(fence);
+ }
+ }
+
+ if (args->busy && read_seqcount_retry(&obj->base.resv->seq, seq))
+ goto retry;
+
+ err = 0;
+out:
+ rcu_read_unlock();
+ return err;
+}