drm/i915: Seal busy-ioctl uABI and prevent leaking of internal ids
Tvrtko was looking through the execbuffer-ioctl and noticed that the
uABI was tightly coupled to our internal engine identifiers. Close
inspection also revealed that we leak those internal engine identifiers
through the busy-ioctl, and those internal identifiers already do not
match the user identifiers. Fortuitiously, there is only one user of the
set of busy rings from the busy-ioctl, and they only wish to choose
between the RENDER and the BLT engines.
Let's fix the userspace ABI while we still can.
v2: Update the uAPI documentation to explain the identifiers.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Testcase: igt/gem_busy
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1452876706-21620-1-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0ed731e..371bbb2 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4358,10 +4358,20 @@
if (ret)
goto unref;
- BUILD_BUG_ON(I915_NUM_RINGS > 16);
- args->busy = obj->active << 16;
- if (obj->last_write_req)
- args->busy |= obj->last_write_req->ring->id;
+ args->busy = 0;
+ if (obj->active) {
+ int i;
+
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ struct drm_i915_gem_request *req;
+
+ req = obj->last_read_req[i];
+ if (req)
+ args->busy |= 1 << (16 + req->ring->exec_id);
+ }
+ if (obj->last_write_req)
+ args->busy |= obj->last_write_req->ring->exec_id;
+ }
unref:
drm_gem_object_unreference(&obj->base);
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 7f47948..73d4347 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2085,6 +2085,7 @@
ring->name = "render ring";
ring->id = RCS;
+ ring->exec_id = I915_EXEC_RENDER;
ring->mmio_base = RENDER_RING_BASE;
logical_ring_default_irqs(ring, GEN8_RCS_IRQ_SHIFT);
@@ -2135,6 +2136,7 @@
ring->name = "bsd ring";
ring->id = VCS;
+ ring->exec_id = I915_EXEC_BSD;
ring->mmio_base = GEN6_BSD_RING_BASE;
logical_ring_default_irqs(ring, GEN8_VCS1_IRQ_SHIFT);
@@ -2150,6 +2152,7 @@
ring->name = "bsd2 ring";
ring->id = VCS2;
+ ring->exec_id = I915_EXEC_BSD;
ring->mmio_base = GEN8_BSD2_RING_BASE;
logical_ring_default_irqs(ring, GEN8_VCS2_IRQ_SHIFT);
@@ -2165,6 +2168,7 @@
ring->name = "blitter ring";
ring->id = BCS;
+ ring->exec_id = I915_EXEC_BLT;
ring->mmio_base = BLT_RING_BASE;
logical_ring_default_irqs(ring, GEN8_BCS_IRQ_SHIFT);
@@ -2180,6 +2184,7 @@
ring->name = "video enhancement ring";
ring->id = VECS;
+ ring->exec_id = I915_EXEC_VEBOX;
ring->mmio_base = VEBOX_RING_BASE;
logical_ring_default_irqs(ring, GEN8_VECS_IRQ_SHIFT);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index d4e33ac..9030e2b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2683,6 +2683,7 @@
ring->name = "render ring";
ring->id = RCS;
+ ring->exec_id = I915_EXEC_RENDER;
ring->mmio_base = RENDER_RING_BASE;
if (INTEL_INFO(dev)->gen >= 8) {
@@ -2831,6 +2832,7 @@
ring->name = "bsd ring";
ring->id = VCS;
+ ring->exec_id = I915_EXEC_BSD;
ring->write_tail = ring_write_tail;
if (INTEL_INFO(dev)->gen >= 6) {
@@ -2907,6 +2909,7 @@
ring->name = "bsd2 ring";
ring->id = VCS2;
+ ring->exec_id = I915_EXEC_BSD;
ring->write_tail = ring_write_tail;
ring->mmio_base = GEN8_BSD2_RING_BASE;
@@ -2937,6 +2940,7 @@
ring->name = "blitter ring";
ring->id = BCS;
+ ring->exec_id = I915_EXEC_BLT;
ring->mmio_base = BLT_RING_BASE;
ring->write_tail = ring_write_tail;
@@ -2994,6 +2998,7 @@
ring->name = "video enhancement ring";
ring->id = VECS;
+ ring->exec_id = I915_EXEC_VEBOX;
ring->mmio_base = VEBOX_RING_BASE;
ring->write_tail = ring_write_tail;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 5b44ca6..b12f2aa 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -157,6 +157,7 @@
} id;
#define I915_NUM_RINGS 5
#define _VCS(n) (VCS + (n))
+ unsigned int exec_id;
u32 mmio_base;
struct drm_device *dev;
struct intel_ringbuffer *buffer;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index acf2102..6a19371 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -812,10 +812,35 @@
/** Handle of the buffer to check for busy */
__u32 handle;
- /** Return busy status (1 if busy, 0 if idle).
- * The high word is used to indicate on which rings the object
- * currently resides:
- * 16:31 - busy (r or r/w) rings (16 render, 17 bsd, 18 blt, etc)
+ /** Return busy status
+ *
+ * A return of 0 implies that the object is idle (after
+ * having flushed any pending activity), and a non-zero return that
+ * the object is still in-flight on the GPU. (The GPU has not yet
+ * signaled completion for all pending requests that reference the
+ * object.)
+ *
+ * The returned dword is split into two fields to indicate both
+ * the engines on which the object is being read, and the
+ * engine on which it is currently being written (if any).
+ *
+ * The low word (bits 0:15) indicate if the object is being written
+ * to by any engine (there can only be one, as the GEM implicit
+ * synchronisation rules force writes to be serialised). Only the
+ * engine for the last write is reported.
+ *
+ * The high word (bits 16:31) are a bitmask of which engines are
+ * currently reading from the object. Multiple engines may be
+ * reading from the object simultaneously.
+ *
+ * The value of each engine is the same as specified in the
+ * EXECBUFFER2 ioctl, i.e. I915_EXEC_RENDER, I915_EXEC_BSD etc.
+ * Note I915_EXEC_DEFAULT is a symbolic value and is mapped to
+ * the I915_EXEC_RENDER engine for execution, and so it is never
+ * reported as active itself. Some hardware may have parallel
+ * execution engines, e.g. multiple media engines, which are
+ * mapped to the same identifier in the EXECBUFFER2 ioctl and
+ * so are not separately reported for busyness.
*/
__u32 busy;
};