[PATCH 01/15] drm/i915: Copy user requested buffers into the error state

Chris Wilson
2017-02-23T16:18:36Z

Introduce a new execobject.flag (EXEC_OBJECT_CAPTURE) that userspace may
use to indicate that it wants the contents of this buffer preserved in
the error state (/sys/class/drm/cardN/error) following a GPU hang
involving this batch.

Use this at your discretion, the contents of the error state. although
compressed, are allocated with GFP_ATOMIC (i.e. limited) and kept for all
eternity (until the error state is destroyed).

Based on an earlier patch by Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Matt Turner <mattst88@gmail.com>
---
drivers/gpu/drm/i915/i915_drv.c | 1 +
drivers/gpu/drm/i915/i915_drv.h | 3 +++
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 12 +++++++++
drivers/gpu/drm/i915/i915_gem_request.c | 16 ++++++++++++
drivers/gpu/drm/i915/i915_gem_request.h | 11 ++++++++
drivers/gpu/drm/i915/i915_gpu_error.c | 40 +++++++++++++++++++++++++++++-
include/uapi/drm/i915_drm.h | 15 ++++++++++-
7 files changed, 96 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 409fc32ce2bd..842c62b96a83 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -353,6 +353,7 @@ static int i915_getparam(struct drm_device *dev, void *data,
case I915_PARAM_HAS_EXEC_ASYNC:
case I915_PARAM_HAS_EXEC_FENCE:
case I915_PARAM_HAS_EXEC_FENCE_DMABUF:
+ case I915_PARAM_HAS_EXEC_CAPTURE:
/* For the time being all of these are always true;
* if some supported hardware does not have one of these
* features this value needs to be provided from
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 440a4725b87f..2cc0253d6ef7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1018,6 +1018,9 @@ struct i915_gpu_state {
u32 *pages[0];
} *ringbuffer, *batchbuffer, *wa_batchbuffer, *ctx, *hws_page;

+ struct drm_i915_error_object **user_bo;
+ long user_bo_count;
+
struct drm_i915_error_object *wa_ctx;

struct drm_i915_error_request {
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 3f2796131410..e8ffe0c9a20e 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1113,6 +1113,18 @@ i915_gem_execbuffer_move_to_gpu(struct drm_i915_gem_request *req,
list_for_each_entry(vma, vmas, exec_list) {
struct drm_i915_gem_object *obj = vma->obj;

+ if (vma->exec_entry->flags & EXEC_OBJECT_CAPTURE) {
+ struct i915_gem_capture_list *capture;
+
+ capture = kmalloc(sizeof(*capture), GFP_KERNEL);
+ if (unlikely(!capture))
+ return -ENOMEM;
+
+ capture->next = req->capture_list;
+ capture->vma = vma;
+ req->capture_list = capture;
+ }
+
if (vma->exec_entry->flags & EXEC_OBJECT_ASYNC)
continue;

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index ad9d4ce07fb6..3a159cac2172 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -286,6 +286,19 @@ void i915_gem_retire_noop(struct i915_gem_active *active,
/* Space left intentionally blank */
}

+static void request_free_capture_list(struct drm_i915_gem_request *request)
+{
+ struct i915_gem_capture_list *capture;
+
+ capture = request->capture_list;
+ while (capture) {
+ struct i915_gem_capture_list *next = capture->next;
+
+ kfree(capture);
+ capture = next;
+ }
+}
+
static void i915_gem_request_retire(struct drm_i915_gem_request *request)
{
struct intel_engine_cs *engine = request->engine;
@@ -320,6 +333,8 @@ static void i915_gem_request_retire(struct drm_i915_gem_request *request)
}
unreserve_seqno(request->engine);

+ request_free_capture_list(request);
+
/* Walk through the active list, calling retire on each. This allows
* objects to track their GPU activity and mark themselves as idle
* when their *last* active request is completed (updating state
@@ -615,6 +630,7 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
req->global_seqno = 0;
req->file_priv = NULL;
req->batch = NULL;
+ req->capture_list = NULL;

/*
* Reserve space in the ring buffer for all the commands required to
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index 0efee879df23..cc24a6c72748 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -73,6 +73,11 @@ struct i915_priotree {
#define I915_PRIORITY_MIN (-I915_PRIORITY_MAX)
};

+struct i915_gem_capture_list {
+ struct i915_gem_capture_list *next;
+ struct i915_vma *vma;
+};
+
/**
* Request queue structure.
*
@@ -167,6 +172,12 @@ struct drm_i915_gem_request {
* error state dump only).
*/
struct i915_vma *batch;
+ /** Additional buffers requested by userspace to be captured upon
+ * a GPU hang. The vma/obj on this list are protected by their
+ * active reference - all objects on this list must also be
+ * on the active_list (of their final request).
+ */
+ struct i915_gem_capture_list *capture_list;
struct list_head active_list;

/** Time at which this request was emitted, in jiffies. */
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 2b1d15668192..76855e1d8795 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -709,6 +709,10 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
print_error_obj(m, dev_priv->engine[i], NULL, obj);
}

+ for (j = 0; j < ee->user_bo_count; j++)
+ print_error_obj(m, dev_priv->engine[i],
+ "user", ee->user_bo[j]);
+
if (ee->num_requests) {
err_printf(m, "%s --- %d requests\n",
dev_priv->engine[i]->name,
@@ -822,11 +826,15 @@ void __i915_gpu_state_free(struct kref *error_ref)
{
struct i915_gpu_state *error =
container_of(error_ref, typeof(*error), ref);
- int i;
+ long i, j;

for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
struct drm_i915_error_engine *ee = &error->engine[i];

+ for (j = 0; j < ee->user_bo_count; j++)
+ i915_error_object_free(ee->user_bo[j]);
+ kfree(ee->user_bo);
+
i915_error_object_free(ee->batchbuffer);
i915_error_object_free(ee->wa_batchbuffer);
i915_error_object_free(ee->ringbuffer);
@@ -1343,6 +1351,35 @@ static void record_context(struct drm_i915_error_context *e,
e->active = ctx->active_count;
}

+static void request_record_user_bo(struct drm_i915_gem_request *request,
+ struct drm_i915_error_engine *ee)
+{
+ struct i915_gem_capture_list *c;
+ struct drm_i915_error_object **bo;
+ long count;
+
+ count = 0;
+ for (c = request->capture_list; c; c = c->next)
+ count++;
+
+ bo = NULL;
+ if (count)
+ bo = kcalloc(count, sizeof(*bo), GFP_ATOMIC);
+ if (!bo)
+ return;
+
+ count = 0;
+ for (c = request->capture_list; c; c = c->next) {
+ bo[count] = i915_error_object_create(request->i915, c->vma);
+ if (!bo[count])
+ break;
+ count++;
+ }
+
+ ee->user_bo = bo;
+ ee->user_bo_count = count;
+}
+
static void i915_gem_record_rings(struct drm_i915_private *dev_priv,
struct i915_gpu_state *error)
{
@@ -1389,6 +1426,7 @@ static void i915_gem_record_rings(struct drm_i915_private *dev_priv,
ee->wa_batchbuffer =
i915_error_object_create(dev_priv,
engine->scratch);
+ request_record_user_bo(request, ee);

ee->ctx =
i915_error_object_create(dev_priv,
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index ebc7641b5252..9eda849df680 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -418,6 +418,12 @@ typedef struct drm_i915_irq_wait {
*/
#define I915_PARAM_HAS_EXEC_FENCE_DMABUF 45

+/* Query whether DRM_I915_GEM_EXECBUFFER2 supports the ability to capture
+ * user specified bufffers for post-mortem debugging of GPU hangs. See
+ * EXEC_OBJECT_CAPTURE.
+ */
+#define I915_PARAM_HAS_EXEC_CAPTURE 46
+
typedef struct drm_i915_getparam {
__s32 param;
/*
@@ -779,8 +785,15 @@ struct drm_i915_gem_exec_object2 {
* I915_PARAM_HAS_EXEC_FENCE to order execbufs and execute them asynchronously.
*/
#define EXEC_OBJECT_ASYNC (1<<6)
+/* Request that the contents of this execobject be copied into the error
+ * state upon a GPU hang involving this batch for post-mortem debugging.
+ * These buffers are recorded in no particular order as "user" in
+ * /sys/class/drm/cardN/error. Query I915_PARAM_HAS_EXEC_CAPTURE to see
+ * if the kernel supports this flag.
+ */
+#define EXEC_OBJECT_CAPTURE (1<<7)
/* All remaining bits are MBZ and RESERVED FOR FUTURE USE */
-#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_ASYNC<<1)
+#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_CAPTURE<<1)
__u64 flags;

union {