drm/i915/selftests: Verify LRC isolation

Record the LRC registers before/after a preemption event to ensure that
the first context sees nothing from the second client; at least in the
normal per-context register state.

References: https://gitlab.freedesktop.org/drm/intel/issues/1233Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200227085723.1961649-12-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/selftest_lrc.c

@@ -4748,6 +4748,538 @@ static int live_lrc_timestamp(void *arg)
 	return 0;
 }
 
+static struct i915_vma *
+create_user_vma(struct i915_address_space *vm, unsigned long size)
+{
+	struct drm_i915_gem_object *obj;
+	struct i915_vma *vma;
+	int err;
+
+	obj = i915_gem_object_create_internal(vm->i915, size);
+	if (IS_ERR(obj))
+		return ERR_CAST(obj);
+
+	vma = i915_vma_instance(obj, 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_gem_object_put(obj);
+		return ERR_PTR(err);
+	}
+
+	return vma;
+}
+
+static struct i915_vma *
+store_context(struct intel_context *ce, struct i915_vma *scratch)
+{
+	struct i915_vma *batch;
+	u32 dw, x, *cs, *hw;
+
+	batch = create_user_vma(ce->vm, SZ_64K);
+	if (IS_ERR(batch))
+		return batch;
+
+	cs = i915_gem_object_pin_map(batch->obj, I915_MAP_WC);
+	if (IS_ERR(cs)) {
+		i915_vma_put(batch);
+		return ERR_CAST(cs);
+	}
+
+	x = 0;
+	dw = 0;
+	hw = ce->engine->pinned_default_state;
+	hw += LRC_STATE_PN * PAGE_SIZE / sizeof(*hw);
+	do {
+		u32 len = hw[dw] & 0x7f;
+
+		if (hw[dw] == 0) {
+			dw++;
+			continue;
+		}
+
+		if ((hw[dw] & GENMASK(31, 23)) != MI_INSTR(0x22, 0)) {
+			dw += len + 2;
+			continue;
+		}
+
+		dw++;
+		len = (len + 1) / 2;
+		while (len--) {
+			*cs++ = MI_STORE_REGISTER_MEM_GEN8;
+			*cs++ = hw[dw];
+			*cs++ = lower_32_bits(scratch->node.start + x);
+			*cs++ = upper_32_bits(scratch->node.start + x);
+
+			dw += 2;
+			x += 4;
+		}
+	} while (dw < PAGE_SIZE / sizeof(u32) &&
+		 (hw[dw] & ~BIT(0)) != MI_BATCH_BUFFER_END);
+
+	*cs++ = MI_BATCH_BUFFER_END;
+
+	i915_gem_object_flush_map(batch->obj);
+	i915_gem_object_unpin_map(batch->obj);
+
+	return batch;
+}
+
+static int move_to_active(struct i915_request *rq,
+			  struct i915_vma *vma,
+			  unsigned int flags)
+{
+	int err;
+
+	i915_vma_lock(vma);
+	err = i915_request_await_object(rq, vma->obj, flags);
+	if (!err)
+		err = i915_vma_move_to_active(vma, rq, flags);
+	i915_vma_unlock(vma);
+
+	return err;
+}
+
+static struct i915_request *
+record_registers(struct intel_context *ce,
+		 struct i915_vma *before,
+		 struct i915_vma *after,
+		 u32 *sema)
+{
+	struct i915_vma *b_before, *b_after;
+	struct i915_request *rq;
+	u32 *cs;
+	int err;
+
+	b_before = store_context(ce, before);
+	if (IS_ERR(b_before))
+		return ERR_CAST(b_before);
+
+	b_after = store_context(ce, after);
+	if (IS_ERR(b_after)) {
+		rq = ERR_CAST(b_after);
+		goto err_before;
+	}
+
+	rq = intel_context_create_request(ce);
+	if (IS_ERR(rq))
+		goto err_after;
+
+	err = move_to_active(rq, before, EXEC_OBJECT_WRITE);
+	if (err)
+		goto err_rq;
+
+	err = move_to_active(rq, b_before, 0);
+	if (err)
+		goto err_rq;
+
+	err = move_to_active(rq, after, EXEC_OBJECT_WRITE);
+	if (err)
+		goto err_rq;
+
+	err = move_to_active(rq, b_after, 0);
+	if (err)
+		goto err_rq;
+
+	cs = intel_ring_begin(rq, 14);
+	if (IS_ERR(cs)) {
+		err = PTR_ERR(cs);
+		goto err_rq;
+	}
+
+	*cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE;
+	*cs++ = MI_BATCH_BUFFER_START_GEN8 | BIT(8);
+	*cs++ = lower_32_bits(b_before->node.start);
+	*cs++ = upper_32_bits(b_before->node.start);
+
+	*cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
+	*cs++ = MI_SEMAPHORE_WAIT |
+		MI_SEMAPHORE_GLOBAL_GTT |
+		MI_SEMAPHORE_POLL |
+		MI_SEMAPHORE_SAD_NEQ_SDD;
+	*cs++ = 0;
+	*cs++ = i915_ggtt_offset(ce->engine->status_page.vma) +
+		offset_in_page(sema);
+	*cs++ = 0;
+	*cs++ = MI_NOOP;
+
+	*cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE;
+	*cs++ = MI_BATCH_BUFFER_START_GEN8 | BIT(8);
+	*cs++ = lower_32_bits(b_after->node.start);
+	*cs++ = upper_32_bits(b_after->node.start);
+
+	intel_ring_advance(rq, cs);
+
+	WRITE_ONCE(*sema, 0);
+	i915_request_get(rq);
+	i915_request_add(rq);
+err_after:
+	i915_vma_put(b_after);
+err_before:
+	i915_vma_put(b_before);
+	return rq;
+
+err_rq:
+	i915_request_add(rq);
+	rq = ERR_PTR(err);
+	goto err_after;
+}
+
+static struct i915_vma *load_context(struct intel_context *ce, u32 poison)
+{
+	struct i915_vma *batch;
+	u32 dw, *cs, *hw;
+
+	batch = create_user_vma(ce->vm, SZ_64K);
+	if (IS_ERR(batch))
+		return batch;
+
+	cs = i915_gem_object_pin_map(batch->obj, I915_MAP_WC);
+	if (IS_ERR(cs)) {
+		i915_vma_put(batch);
+		return ERR_CAST(cs);
+	}
+
+	dw = 0;
+	hw = ce->engine->pinned_default_state;
+	hw += LRC_STATE_PN * PAGE_SIZE / sizeof(*hw);
+	do {
+		u32 len = hw[dw] & 0x7f;
+
+		if (hw[dw] == 0) {
+			dw++;
+			continue;
+		}
+
+		if ((hw[dw] & GENMASK(31, 23)) != MI_INSTR(0x22, 0)) {
+			dw += len + 2;
+			continue;
+		}
+
+		dw++;
+		len = (len + 1) / 2;
+		*cs++ = MI_LOAD_REGISTER_IMM(len);
+		while (len--) {
+			*cs++ = hw[dw];
+			*cs++ = poison;
+			dw += 2;
+		}
+	} while (dw < PAGE_SIZE / sizeof(u32) &&
+		 (hw[dw] & ~BIT(0)) != MI_BATCH_BUFFER_END);
+
+	*cs++ = MI_BATCH_BUFFER_END;
+
+	i915_gem_object_flush_map(batch->obj);
+	i915_gem_object_unpin_map(batch->obj);
+
+	return batch;
+}
+
+static int poison_registers(struct intel_context *ce, u32 poison, u32 *sema)
+{
+	struct i915_request *rq;
+	struct i915_vma *batch;
+	u32 *cs;
+	int err;
+
+	batch = load_context(ce, poison);
+	if (IS_ERR(batch))
+		return PTR_ERR(batch);
+
+	rq = intel_context_create_request(ce);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto err_batch;
+	}
+
+	err = move_to_active(rq, batch, 0);
+	if (err)
+		goto err_rq;
+
+	cs = intel_ring_begin(rq, 8);
+	if (IS_ERR(cs)) {
+		err = PTR_ERR(cs);
+		goto err_rq;
+	}
+
+	*cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE;
+	*cs++ = MI_BATCH_BUFFER_START_GEN8 | BIT(8);
+	*cs++ = lower_32_bits(batch->node.start);
+	*cs++ = upper_32_bits(batch->node.start);
+
+	*cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
+	*cs++ = i915_ggtt_offset(ce->engine->status_page.vma) +
+		offset_in_page(sema);
+	*cs++ = 0;
+	*cs++ = 1;
+
+	intel_ring_advance(rq, cs);
+
+	rq->sched.attr.priority = I915_PRIORITY_BARRIER;
+err_rq:
+	i915_request_add(rq);
+err_batch:
+	i915_vma_put(batch);
+	return err;
+}
+
+static bool is_moving(u32 a, u32 b)
+{
+	return a != b;
+}
+
+static int compare_isolation(struct intel_engine_cs *engine,
+			     struct i915_vma *ref[2],
+			     struct i915_vma *result[2],
+			     struct intel_context *ce,
+			     u32 poison)
+{
+	u32 x, dw, *hw, *lrc;
+	u32 *A[2], *B[2];
+	int err = 0;
+
+	A[0] = i915_gem_object_pin_map(ref[0]->obj, I915_MAP_WC);
+	if (IS_ERR(A[0]))
+		return PTR_ERR(A[0]);
+
+	A[1] = i915_gem_object_pin_map(ref[1]->obj, I915_MAP_WC);
+	if (IS_ERR(A[1])) {
+		err = PTR_ERR(A[1]);
+		goto err_A0;
+	}
+
+	B[0] = i915_gem_object_pin_map(result[0]->obj, I915_MAP_WC);
+	if (IS_ERR(B[0])) {
+		err = PTR_ERR(B[0]);
+		goto err_A1;
+	}
+
+	B[1] = i915_gem_object_pin_map(result[1]->obj, I915_MAP_WC);
+	if (IS_ERR(B[1])) {
+		err = PTR_ERR(B[1]);
+		goto err_B0;
+	}
+
+	lrc = i915_gem_object_pin_map(ce->state->obj,
+				      i915_coherent_map_type(engine->i915));
+	if (IS_ERR(lrc)) {
+		err = PTR_ERR(lrc);
+		goto err_B1;
+	}
+	lrc += LRC_STATE_PN * PAGE_SIZE / sizeof(*hw);
+
+	x = 0;
+	dw = 0;
+	hw = engine->pinned_default_state;
+	hw += LRC_STATE_PN * PAGE_SIZE / sizeof(*hw);
+	do {
+		u32 len = hw[dw] & 0x7f;
+
+		if (hw[dw] == 0) {
+			dw++;
+			continue;
+		}
+
+		if ((hw[dw] & GENMASK(31, 23)) != MI_INSTR(0x22, 0)) {
+			dw += len + 2;
+			continue;
+		}
+
+		dw++;
+		len = (len + 1) / 2;
+		while (len--) {
+			if (!is_moving(A[0][x], A[1][x]) &&
+			    (A[0][x] != B[0][x] || A[1][x] != B[1][x])) {
+				switch (hw[dw] & 4095) {
+				case 0x30: /* RING_HEAD */
+				case 0x34: /* RING_TAIL */
+					break;
+
+				default:
+					pr_err("%s[%d]: Mismatch for register %4x, default %08x, reference %08x, result (%08x, %08x), poison %08x, context %08x\n",
+					       engine->name, dw,
+					       hw[dw], hw[dw + 1],
+					       A[0][x], B[0][x], B[1][x],
+					       poison, lrc[dw + 1]);
+					err = -EINVAL;
+					break;
+				}
+			}
+			dw += 2;
+			x++;
+		}
+	} while (dw < PAGE_SIZE / sizeof(u32) &&
+		 (hw[dw] & ~BIT(0)) != MI_BATCH_BUFFER_END);
+
+	i915_gem_object_unpin_map(ce->state->obj);
+err_B1:
+	i915_gem_object_unpin_map(result[1]->obj);
+err_B0:
+	i915_gem_object_unpin_map(result[0]->obj);
+err_A1:
+	i915_gem_object_unpin_map(ref[1]->obj);
+err_A0:
+	i915_gem_object_unpin_map(ref[0]->obj);
+	return err;
+}
+
+static int __lrc_isolation(struct intel_engine_cs *engine, u32 poison)
+{
+	u32 *sema = memset32(engine->status_page.addr + 1000, 0, 1);
+	struct i915_vma *ref[2], *result[2];
+	struct intel_context *A, *B;
+	struct i915_request *rq;
+	int err;
+
+	A = intel_context_create(engine);
+	if (IS_ERR(A))
+		return PTR_ERR(A);
+
+	B = intel_context_create(engine);
+	if (IS_ERR(B)) {
+		err = PTR_ERR(B);
+		goto err_A;
+	}
+
+	ref[0] = create_user_vma(A->vm, SZ_64K);
+	if (IS_ERR(ref[0])) {
+		err = PTR_ERR(ref[0]);
+		goto err_B;
+	}
+
+	ref[1] = create_user_vma(A->vm, SZ_64K);
+	if (IS_ERR(ref[1])) {
+		err = PTR_ERR(ref[1]);
+		goto err_ref0;
+	}
+
+	rq = record_registers(A, ref[0], ref[1], sema);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto err_ref1;
+	}
+
+	WRITE_ONCE(*sema, 1);
+	wmb();
+
+	if (i915_request_wait(rq, 0, HZ / 2) < 0) {
+		i915_request_put(rq);
+		err = -ETIME;
+		goto err_ref1;
+	}
+	i915_request_put(rq);
+
+	result[0] = create_user_vma(A->vm, SZ_64K);
+	if (IS_ERR(result[0])) {
+		err = PTR_ERR(result[0]);
+		goto err_ref1;
+	}
+
+	result[1] = create_user_vma(A->vm, SZ_64K);
+	if (IS_ERR(result[1])) {
+		err = PTR_ERR(result[1]);
+		goto err_result0;
+	}
+
+	rq = record_registers(A, result[0], result[1], sema);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto err_result1;
+	}
+
+	err = poison_registers(B, poison, sema);
+	if (err) {
+		WRITE_ONCE(*sema, -1);
+		i915_request_put(rq);
+		goto err_result1;
+	}
+
+	if (i915_request_wait(rq, 0, HZ / 2) < 0) {
+		i915_request_put(rq);
+		err = -ETIME;
+		goto err_result1;
+	}
+	i915_request_put(rq);
+
+	err = compare_isolation(engine, ref, result, A, poison);
+
+err_result1:
+	i915_vma_put(result[1]);
+err_result0:
+	i915_vma_put(result[0]);
+err_ref1:
+	i915_vma_put(ref[1]);
+err_ref0:
+	i915_vma_put(ref[0]);
+err_B:
+	intel_context_put(B);
+err_A:
+	intel_context_put(A);
+	return err;
+}
+
+static bool skip_isolation(const struct intel_engine_cs *engine)
+{
+	if (engine->class == COPY_ENGINE_CLASS && INTEL_GEN(engine->i915) == 9)
+		return true;
+
+	if (engine->class == RENDER_CLASS && INTEL_GEN(engine->i915) == 11)
+		return true;
+
+	return false;
+}
+
+static int live_lrc_isolation(void *arg)
+{
+	struct intel_gt *gt = arg;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	const u32 poison[] = {
+		STACK_MAGIC,
+		0x3a3a3a3a,
+		0xc5c5c5c5,
+		0xffffffff,
+	};
+
+	/*
+	 * Our goal is try and verify that per-context state cannot be
+	 * tampered with by another non-privileged client.
+	 *
+	 * We take the list of context registers from the LRI in the default
+	 * context image and attempt to modify that list from a remote context.
+	 */
+
+	for_each_engine(engine, gt, id) {
+		int err = 0;
+		int i;
+
+		/* Just don't even ask */
+		if (!IS_ENABLED(CONFIG_DRM_I915_SELFTEST_BROKEN) &&
+		    skip_isolation(engine))
+			continue;
+
+		intel_engine_pm_get(engine);
+		if (engine->pinned_default_state) {
+			for (i = 0; i < ARRAY_SIZE(poison); i++) {
+				err = __lrc_isolation(engine, poison[i]);
+				if (err)
+					break;
+			}
+		}
+		intel_engine_pm_put(engine);
+		if (igt_flush_test(gt->i915))
+			err = -EIO;
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int __live_pphwsp_runtime(struct intel_engine_cs *engine)
 {
 	struct intel_context *ce;
@@ -4845,6 +5377,7 @@ int intel_lrc_live_selftests(struct drm_i915_private *i915)
 		SUBTEST(live_lrc_fixed),
 		SUBTEST(live_lrc_state),
 		SUBTEST(live_lrc_gpr),
+		SUBTEST(live_lrc_isolation),
 		SUBTEST(live_lrc_timestamp),
 		SUBTEST(live_pphwsp_runtime),
 	};