The vm of two contexts are supposed to be independent, such that a stray
write by one cannot be detected by another. Normally the GTT is filled
explicitly by userspace, but the space in between objects is filled with
a scratch page -- and that scratch page should be able to form an
inter-context backchannel.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
---
.../gpu/drm/i915/selftests/i915_gem_context.c | 318 ++++++++++++++++++
1 file changed, 318 insertions(+)
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
index 1be3b67a7c48..aed6018821a1 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
@@ -760,6 +760,323 @@ static int igt_ctx_readonly(void *arg)
return err;
}
+static int check_scratch(struct i915_gem_context *ctx, u64 offset)
+{
+ struct drm_mm_node *node =
+ __drm_mm_interval_first(&ctx->ppgtt->vm.mm,
+ offset, offset + sizeof(u32) - 1);
+ if (!node || node->start > offset)
+ return 0;
+
+ GEM_BUG_ON(offset >= node->start + node->size);
+
+ pr_err("Target offset 0x%08x_%08x overlaps with a node in the mm!\n",
+ upper_32_bits(offset), lower_32_bits(offset));
+ return -EINVAL;
+}
+
+static int write_to_scratch(struct i915_gem_context *ctx,
+ struct intel_engine_cs *engine,
+ u64 offset, u32 value)
+{
+ struct drm_i915_private *i915 = ctx->i915;
+ struct drm_i915_gem_object *obj;
+ struct i915_request *rq;
+ struct i915_vma *vma;
+ u32 *cmd;
+ int err;
+
+ GEM_BUG_ON(offset < I915_GTT_PAGE_SIZE);
+
+ obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
+ if (IS_ERR(obj))
+ return PTR_ERR(obj);
+
+ cmd = i915_gem_object_pin_map(obj, I915_MAP_WB);
+ if (IS_ERR(cmd)) {
+ err = PTR_ERR(cmd);
+ goto err;
+ }
+
+ *cmd++ = MI_STORE_DWORD_IMM_GEN4;
+ if (INTEL_GEN(i915) >= 8) {
+ *cmd++ = lower_32_bits(offset);
+ *cmd++ = upper_32_bits(offset);
+ } else {
+ *cmd++ = 0;
+ *cmd++ = offset;
+ }
+ *cmd++ = value;
+ *cmd = MI_BATCH_BUFFER_END;
+ i915_gem_object_unpin_map(obj);
+
+ err = i915_gem_object_set_to_gtt_domain(obj, false);
+ if (err)
+ goto err;
+
+ vma = i915_vma_instance(obj, &ctx->ppgtt->vm, NULL);
+ if (IS_ERR(vma)) {
+ err = PTR_ERR(vma);
+ goto err;
+ }
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER | PIN_OFFSET_FIXED);
+ if (err)
+ goto err;
+
+ err = check_scratch(ctx, offset);
+ if (err)
+ goto err_unpin;
+
+ rq = i915_request_alloc(engine, ctx);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_unpin;
+ }
+
+ err = engine->emit_bb_start(rq, vma->node.start, vma->node.size, 0);
+ if (err)
+ goto err_request;
+
+ err = i915_vma_move_to_active(vma, rq, 0);
+ if (err)
+ goto skip_request;
+
+ i915_gem_object_set_active_reference(obj);
+ i915_vma_unpin(vma);
+ i915_vma_close(vma);
+
+ i915_request_add(rq);
+
+ return 0;
+
+skip_request:
+ i915_request_skip(rq, err);
+err_request:
+ i915_request_add(rq);
+err_unpin:
+ i915_vma_unpin(vma);
+err:
+ i915_gem_object_put(obj);
+ return err;
+}
+
+static int read_from_scratch(struct i915_gem_context *ctx,
+ struct intel_engine_cs *engine,
+ u64 offset, u32 *value)
+{
+ struct drm_i915_private *i915 = ctx->i915;
+ struct drm_i915_gem_object *obj;
+ struct i915_request *rq;
+ struct i915_vma *vma;
+ const u32 CS_GPR0 = engine->mmio_base + 0x600;
+ const u32 result = 0x100;
+ u32 *cmd;
+ int err;
+
+ GEM_BUG_ON(offset < I915_GTT_PAGE_SIZE);
+
+ obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
+ if (IS_ERR(obj))
+ return PTR_ERR(obj);
+
+ cmd = i915_gem_object_pin_map(obj, I915_MAP_WB);
+ if (IS_ERR(cmd)) {
+ err = PTR_ERR(cmd);
+ goto err;
+ }
+
+ memset(cmd, POISON_INUSE, PAGE_SIZE);
+ if (INTEL_GEN(i915) >= 8) {
+ *cmd++ = MI_LOAD_REGISTER_MEM_GEN8;
+ *cmd++ = CS_GPR0;
+ *cmd++ = lower_32_bits(offset);
+ *cmd++ = upper_32_bits(offset);
+ *cmd++ = MI_STORE_REGISTER_MEM_GEN8;
+ *cmd++ = CS_GPR0;
+ *cmd++ = result;
+ *cmd++ = 0;
+ } else {
+ *cmd++ = MI_LOAD_REGISTER_MEM;
+ *cmd++ = CS_GPR0;
+ *cmd++ = offset;
+ *cmd++ = MI_STORE_REGISTER_MEM;
+ *cmd++ = CS_GPR0;
+ *cmd++ = result;
+ }
+ *cmd = MI_BATCH_BUFFER_END;
+ i915_gem_object_unpin_map(obj);
+
+ err = i915_gem_object_set_to_gtt_domain(obj, false);
+ if (err)
+ goto err;
+
+ vma = i915_vma_instance(obj, &ctx->ppgtt->vm, NULL);
+ if (IS_ERR(vma)) {
+ err = PTR_ERR(vma);
+ goto err;
+ }
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER | PIN_OFFSET_FIXED);
+ if (err)
+ goto err;
+
+ err = check_scratch(ctx, offset);
+ if (err)
+ goto err_unpin;
+
+ rq = i915_request_alloc(engine, ctx);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_unpin;
+ }
+
+ err = engine->emit_bb_start(rq, vma->node.start, vma->node.size, 0);
+ if (err)
+ goto err_request;
+
+ err = i915_vma_move_to_active(vma, rq, EXEC_OBJECT_WRITE);
+ if (err)
+ goto skip_request;
+
+ i915_vma_unpin(vma);
+ i915_vma_close(vma);
+
+ i915_request_add(rq);
+
+ err = i915_gem_object_set_to_cpu_domain(obj, false);
+ if (err)
+ goto err;
+
+ cmd = i915_gem_object_pin_map(obj, I915_MAP_WB);
+ if (IS_ERR(cmd)) {
+ err = PTR_ERR(cmd);
+ goto err;
+ }
+
+ *value = cmd[result / sizeof(*cmd)];
+ i915_gem_object_unpin_map(obj);
+ i915_gem_object_put(obj);
+
+ return 0;
+
+skip_request:
+ i915_request_skip(rq, err);
+err_request:
+ i915_request_add(rq);
+err_unpin:
+ i915_vma_unpin(vma);
+err:
+ i915_gem_object_put(obj);
+ return err;
+}
+
+static int igt_vm_isolation(void *arg)
+{
+ struct drm_i915_private *i915 = arg;
+ struct i915_gem_context *ctx_a, *ctx_b;
+ struct intel_engine_cs *engine;
+ struct drm_file *file;
+ I915_RND_STATE(prng);
+ unsigned long count;
+ struct live_test t;
+ unsigned int id;
+ u64 vm_total;
+ int err;
+
+ if (INTEL_GEN(i915) < 7)
+ return 0;
+
+ /*
+ * The simple goal here is that a write into one context is not
+ * observed in a second (separate page tables and scratch).
+ */
+
+ file = mock_file(i915);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ mutex_lock(&i915->drm.struct_mutex);
+
+ err = begin_live_test(&t, i915, __func__, "");
+ if (err)
+ goto out_unlock;
+
+ ctx_a = i915_gem_create_context(i915, file->driver_priv);
+ if (IS_ERR(ctx_a)) {
+ err = PTR_ERR(ctx_a);
+ goto out_unlock;
+ }
+
+ ctx_b = i915_gem_create_context(i915, file->driver_priv);
+ if (IS_ERR(ctx_b)) {
+ err = PTR_ERR(ctx_b);
+ goto out_unlock;
+ }
+
+ /* We can only test vm isolation, if the vm are distinct */
+ if (ctx_a->ppgtt == ctx_b->ppgtt)
+ goto out_unlock;
+
+ vm_total = ctx_a->ppgtt->vm.total;
+ GEM_BUG_ON(ctx_b->ppgtt->vm.total != vm_total);
+ vm_total -= I915_GTT_PAGE_SIZE;
+
+ intel_runtime_pm_get(i915);
+
+ count = 0;
+ for_each_engine(engine, i915, id) {
+ IGT_TIMEOUT(end_time);
+ unsigned long this = 0;
+
+ if (!intel_engine_can_store_dword(engine))
+ continue;
+
+ while (!__igt_timeout(end_time, NULL)) {
+ u32 value = 0xc5c5c5c5;
+ u64 offset;
+
+ div64_u64_rem(i915_prandom_u64_state(&prng),
+ vm_total, &offset);
+ offset &= ~sizeof(u32);
+ offset += I915_GTT_PAGE_SIZE;
+
+ err = write_to_scratch(ctx_a, engine,
+ offset, 0xdeadbeef);
+ if (err == 0)
+ err = read_from_scratch(ctx_b, engine,
+ offset, &value);
+ if (err)
+ goto out_rpm;
+
+ if (value) {
+ pr_err("%s: Read %08x from scratch (offset 0x%08x_%08x), after %lu reads!\n",
+ engine->name, value,
+ upper_32_bits(offset),
+ lower_32_bits(offset),
+ this);
+ err = -EINVAL;
+ goto out_rpm;
+ }
+
+ this++;
+ }
+ count += this;
+ }
+ pr_info("Checked %lu scratch offsets across %d engines\n",
+ count, INTEL_INFO(i915)->num_rings);
+
+out_rpm:
+ intel_runtime_pm_put(i915);
+out_unlock:
+ if (end_live_test(&t))
+ err = -EIO;
+ mutex_unlock(&i915->drm.struct_mutex);
+
+ mock_file_free(i915, file);
+ return err;
+}
+
static __maybe_unused const char *
__engine_name(struct drm_i915_private *i915, unsigned int engines)
{
@@ -915,6 +1232,7 @@ int i915_gem_context_live_selftests(struct drm_i915_private *dev_priv)
SUBTEST(live_nop_switch),
SUBTEST(igt_ctx_exec),
SUBTEST(igt_ctx_readonly),
+ SUBTEST(igt_vm_isolation),
};
if (i915_terminally_wedged(&dev_priv->gpu_error))
--
2.19.1
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