[Intel-gfx] [PATCH v2] drm/i915/selftests: Try to detect rollback during batchbuffer preemption
Chris Wilson
chris at chris-wilson.co.uk
Wed Apr 22 10:09:03 UTC 2020
Since batch buffers dominant execution time, most preemption requests
should naturally occur during execution of a batch buffer. We wish to
verify that should a preemption occur within a batch buffer, when we
come to restart that batch buffer, it occurs at the interrupted
instruction and most importantly does not rollback to an earlier point.
v2: Do not clear the GPR at the start of the batch, but rely on them
being clear for new contexts.
Suggested-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
drivers/gpu/drm/i915/gt/selftest_lrc.c | 329 ++++++++++++++++++++++++-
1 file changed, 328 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
index 6f5e35afe1b2..fc3f9a248764 100644
--- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
@@ -21,7 +21,8 @@
#include "gem/selftests/mock_context.h"
#define CS_GPR(engine, n) ((engine)->mmio_base + 0x600 + (n) * 4)
-#define NUM_GPR_DW (16 * 2) /* each GPR is 2 dwords */
+#define NUM_GPR 16
+#define NUM_GPR_DW (NUM_GPR * 2) /* each GPR is 2 dwords */
static struct i915_vma *create_scratch(struct intel_gt *gt)
{
@@ -2791,6 +2792,331 @@ static int live_preempt_gang(void *arg)
return 0;
}
+static struct i915_vma *
+create_gpr_user(struct intel_engine_cs *engine,
+ struct i915_vma *result,
+ unsigned int offset)
+{
+ struct drm_i915_gem_object *obj;
+ struct i915_vma *vma;
+ u32 *cs;
+ int err;
+ int i;
+
+ obj = i915_gem_object_create_internal(engine->i915, 4096);
+ if (IS_ERR(obj))
+ return ERR_CAST(obj);
+
+ vma = i915_vma_instance(obj, result->vm, NULL);
+ if (IS_ERR(vma)) {
+ i915_gem_object_put(obj);
+ return vma;
+ }
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER);
+ if (err) {
+ i915_vma_put(vma);
+ return ERR_PTR(err);
+ }
+
+ cs = i915_gem_object_pin_map(obj, I915_MAP_WC);
+ if (IS_ERR(cs)) {
+ i915_vma_put(vma);
+ return ERR_CAST(cs);
+ }
+
+ /* All GPR are clear for new contexts. We use GPR(0) as a constant */
+ *cs++ = MI_LOAD_REGISTER_IMM(1);
+ *cs++ = CS_GPR(engine, 0);
+ *cs++ = 1;
+
+ for (i = 1; i < NUM_GPR; i++) {
+ u64 addr;
+
+ /*
+ * Perform: GPR[i]++
+ *
+ * As we read and write into the context saved GPR[i], if
+ * we restart this batch buffer from an earlier point, we
+ * will repeat the increment and store a value > 1.
+ */
+ *cs++ = MI_MATH(4);
+ *cs++ = MI_MATH_LOAD(MI_MATH_REG_SRCA, MI_MATH_REG(i));
+ *cs++ = MI_MATH_LOAD(MI_MATH_REG_SRCB, MI_MATH_REG(0));
+ *cs++ = MI_MATH_ADD;
+ *cs++ = MI_MATH_STORE(MI_MATH_REG(i), MI_MATH_REG_ACCU);
+
+ addr = result->node.start + offset + i * sizeof(*cs);
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8;
+ *cs++ = CS_GPR(engine, 2 * i);
+ *cs++ = lower_32_bits(addr);
+ *cs++ = upper_32_bits(addr);
+
+ *cs++ = MI_SEMAPHORE_WAIT |
+ MI_SEMAPHORE_POLL |
+ MI_SEMAPHORE_SAD_GTE_SDD;
+ *cs++ = i;
+ *cs++ = lower_32_bits(result->node.start);
+ *cs++ = upper_32_bits(result->node.start);
+ }
+
+ *cs++ = MI_BATCH_BUFFER_END;
+ i915_gem_object_flush_map(obj);
+ i915_gem_object_unpin_map(obj);
+
+ return vma;
+}
+
+static struct i915_vma *create_global(struct intel_gt *gt, size_t sz)
+{
+ struct drm_i915_gem_object *obj;
+ struct i915_vma *vma;
+ int err;
+
+ obj = i915_gem_object_create_internal(gt->i915, sz);
+ if (IS_ERR(obj))
+ return ERR_CAST(obj);
+
+ vma = i915_vma_instance(obj, >->ggtt->vm, NULL);
+ if (IS_ERR(vma)) {
+ i915_gem_object_put(obj);
+ return vma;
+ }
+
+ err = i915_ggtt_pin(vma, 0, 0);
+ if (err) {
+ i915_vma_put(vma);
+ return ERR_PTR(err);
+ }
+
+ return vma;
+}
+
+static struct i915_request *
+create_gpr_client(struct intel_engine_cs *engine,
+ struct i915_vma *global,
+ unsigned int offset)
+{
+ struct i915_vma *batch, *vma;
+ struct intel_context *ce;
+ struct i915_request *rq;
+ int err;
+
+ ce = intel_context_create(engine);
+ if (IS_ERR(ce))
+ return ERR_CAST(ce);
+
+ vma = i915_vma_instance(global->obj, ce->vm, NULL);
+ if (IS_ERR(vma)) {
+ err = PTR_ERR(vma);
+ goto out_ce;
+ }
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER);
+ if (err)
+ goto out_ce;
+
+ batch = create_gpr_user(engine, vma, offset);
+ if (IS_ERR(batch)) {
+ err = PTR_ERR(batch);
+ goto out_vma;
+ }
+
+ rq = intel_context_create_request(ce);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto out_batch;
+ }
+
+ i915_vma_lock(vma);
+ err = i915_request_await_object(rq, vma->obj, false);
+ if (!err)
+ err = i915_vma_move_to_active(vma, rq, 0);
+ i915_vma_unlock(vma);
+
+ i915_vma_lock(batch);
+ if (!err)
+ err = i915_request_await_object(rq, batch->obj, false);
+ if (!err)
+ err = i915_vma_move_to_active(batch, rq, 0);
+ if (!err)
+ err = rq->engine->emit_bb_start(rq,
+ batch->node.start,
+ PAGE_SIZE, 0);
+ i915_vma_unlock(batch);
+ i915_vma_unpin(batch);
+
+ if (!err)
+ i915_request_get(rq);
+ i915_request_add(rq);
+
+out_batch:
+ i915_vma_put(batch);
+out_vma:
+ i915_vma_unpin(vma);
+out_ce:
+ intel_context_put(ce);
+ return err ? ERR_PTR(err) : rq;
+}
+
+static int preempt_user(struct intel_engine_cs *engine,
+ struct i915_vma *global,
+ int id)
+{
+ struct i915_sched_attr attr = {
+ .priority = I915_PRIORITY_MAX
+ };
+ struct i915_request *rq;
+ int err = 0;
+ u32 *cs;
+
+ rq = intel_engine_create_kernel_request(engine);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ cs = intel_ring_begin(rq, 4);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
+ *cs++ = i915_ggtt_offset(global);
+ *cs++ = 0;
+ *cs++ = id;
+
+ intel_ring_advance(rq, cs);
+
+ i915_request_get(rq);
+ i915_request_add(rq);
+
+ engine->schedule(rq, &attr);
+
+ if (i915_request_wait(rq, 0, HZ / 2) < 0)
+ err = -ETIME;
+ i915_request_put(rq);
+
+ return err;
+}
+
+static int live_preempt_user(void *arg)
+{
+ struct intel_gt *gt = arg;
+ struct intel_engine_cs *engine;
+ struct i915_vma *global;
+ enum intel_engine_id id;
+ u32 *result;
+ int err = 0;
+
+ if (!HAS_LOGICAL_RING_PREEMPTION(gt->i915))
+ return 0;
+
+ /*
+ * In our other tests, we look at preemption in carefully
+ * controlled conditions in the ringbuffer. Since most of the
+ * time is spent in user batches, most of our preemptions naturally
+ * occur there. We want to verify that when we preempt inside a batch
+ * we continue on from the current instruction and do not roll back
+ * to the start, or another earlier arbitration point.
+ *
+ * To verify this, we create a batch which is a mixture of
+ * MI_MATH (gpr++) MI_SRM (gpr) and preemption points. Then with
+ * a few preempting contexts thrown into the mix, we look for any
+ * repeated instructions (which show up as incorrect values).
+ */
+
+ global = create_global(gt, 4096);
+ if (IS_ERR(global))
+ return PTR_ERR(global);
+
+ result = i915_gem_object_pin_map(global->obj, I915_MAP_WC);
+ if (IS_ERR(result)) {
+ i915_vma_unpin_and_release(&global, 0);
+ return PTR_ERR(result);
+ }
+
+ for_each_engine(engine, gt, id) {
+ struct i915_request *client[3] = {};
+ struct igt_live_test t;
+ int i;
+
+ if (!intel_engine_has_preemption(engine))
+ continue;
+
+ if (IS_GEN(gt->i915, 8) && engine->class != RENDER_CLASS)
+ continue; /* we need per-context GPR */
+
+ if (igt_live_test_begin(&t, gt->i915, __func__, engine->name)) {
+ err = -EIO;
+ break;
+ }
+
+ memset(result, 0, 4096);
+
+ for (i = 0; i < ARRAY_SIZE(client); i++) {
+ struct i915_request *rq;
+
+ rq = create_gpr_client(engine, global,
+ NUM_GPR * i * sizeof(u32));
+ if (IS_ERR(rq))
+ goto end_test;
+
+ client[i] = rq;
+ }
+
+ /* Continuously preempt the set of 3 running contexts */
+ for (i = 1; i <= NUM_GPR; i++) {
+ err = preempt_user(engine, global, i);
+ if (err)
+ goto end_test;
+ }
+
+ if (READ_ONCE(result[0]) != NUM_GPR) {
+ pr_err("%s: Failed to release semaphore\n",
+ engine->name);
+ err = -EIO;
+ goto end_test;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(client); i++) {
+ int gpr;
+
+ if (i915_request_wait(client[i], 0, HZ / 2) < 0) {
+ err = -ETIME;
+ goto end_test;
+ }
+
+ for (gpr = 1; gpr < NUM_GPR; gpr++) {
+ if (result[NUM_GPR * i + gpr] != 1) {
+ pr_err("%s: Invalid result, client %d, gpr %d, result: %d\n",
+ engine->name,
+ i, gpr, result[NUM_GPR * i + gpr]);
+ err = -EINVAL;
+ goto end_test;
+ }
+ }
+ }
+
+end_test:
+ for (i = 0; i < ARRAY_SIZE(client); i++) {
+ if (!client[i])
+ break;
+
+ i915_request_put(client[i]);
+ }
+
+ /* Flush the semaphores on error */
+ smp_store_mb(result[0], -1);
+ if (igt_live_test_end(&t))
+ err = -EIO;
+ if (err)
+ break;
+ }
+
+ i915_vma_unpin_and_release(&global, I915_VMA_RELEASE_MAP);
+ return err;
+}
+
static int live_preempt_timeout(void *arg)
{
struct intel_gt *gt = arg;
@@ -3998,6 +4324,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
SUBTEST(live_chain_preempt),
SUBTEST(live_preempt_gang),
SUBTEST(live_preempt_timeout),
+ SUBTEST(live_preempt_user),
SUBTEST(live_preempt_smoke),
SUBTEST(live_virtual_engine),
SUBTEST(live_virtual_mask),
--
2.20.1
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