No unprivileged context should ever be allowed to modify state that is
visible to another; there should be no backchannels available or control
leakage for malicious actors.
This test tries to write to a set of random registers using
non-privileged instructions (ala userspace). It should only be allowed
to write into its context state, and all writes should not be visible to
a second context. To verify this, we store the value of the register
before writing to it in context A (as this should be the default value
inherited from the golden context state) and do a read back from context
B of the same register. The reads from both contexts should be identical,
the default value, except for a few free running counters (either global
or local).
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
.../drm/i915/gem/selftests/i915_gem_context.c | 355 ++++++++++++++++++
1 file changed, 355 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
index f4f933240b39..3ef542c52d85 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
@@ -1865,6 +1865,360 @@ static int igt_vm_isolation(void *arg)
return err;
}
+static struct i915_vma *create_vma(struct i915_address_space *vm, size_t sz)
+{
+ struct drm_i915_gem_object *obj;
+ struct i915_vma *vma;
+
+ obj = i915_gem_object_create_internal(vm->i915, sz);
+ 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;
+}
+
+static int iso_in(struct i915_gem_context *ctx,
+ struct intel_engine_cs *engine,
+ struct drm_i915_gem_object *obj,
+ u32 *ctl)
+{
+ struct i915_vma *batch, *vma;
+ struct i915_request *rq;
+ u32 *cs;
+ int err;
+ int i;
+
+ batch = create_vma(ctx->vm, 64 << 10);
+ if (IS_ERR(batch))
+ return PTR_ERR(batch);
+
+ vma = i915_vma_instance(obj, ctx->vm, NULL);
+ if (IS_ERR(vma)) {
+ err = PTR_ERR(vma);
+ goto err_batch;
+ }
+
+ err = i915_vma_pin(batch, 0, 0, PIN_USER);
+ if (err)
+ goto err_batch;
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER);
+ if (err)
+ goto err_unpin_batch;
+
+ cs = i915_gem_object_pin_map(batch->obj, I915_MAP_WC);
+ if (IS_ERR(cs)) {
+ err = PTR_ERR(cs);
+ goto err_vma;
+ }
+
+ for (i = 0; i < 1024; i++) {
+ u64 addr = vma->node.start + (4 * i + 2) * sizeof(u32);
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8;
+ *cs++ = ctl[4 * i + 0];
+ *cs++ = lower_32_bits(addr);
+ *cs++ = upper_32_bits(addr);
+
+ *cs++ = MI_LOAD_REGISTER_IMM(1);
+ *cs++ = ctl[4 * i + 0];
+ *cs++ = ctl[4 * i + 1];
+ }
+ *cs++ = MI_BATCH_BUFFER_END;
+
+ i915_gem_object_flush_map(obj);
+ i915_gem_object_unpin_map(obj);
+
+ rq = igt_request_alloc(ctx, engine);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_vma;
+ }
+
+ i915_vma_lock(vma);
+ err = i915_request_await_object(rq, vma->obj, true);
+ if (err == 0)
+ err = i915_vma_move_to_active(vma, rq, EXEC_OBJECT_WRITE);
+ i915_vma_unlock(vma);
+ if (err)
+ goto err_rq;
+
+ i915_vma_lock(vma);
+ err = i915_request_await_object(rq, batch->obj, false);
+ if (err == 0)
+ err = i915_vma_move_to_active(batch, rq, 0);
+ i915_vma_unlock(vma);
+ if (err)
+ goto err_rq;
+
+ err = engine->emit_bb_start(rq, batch->node.start, batch->node.size, 0);
+
+err_rq:
+ i915_request_add(rq);
+err_vma:
+ i915_vma_unpin(vma);
+err_unpin_batch:
+ i915_vma_unpin(batch);
+err_batch:
+ i915_vma_put(batch);
+ return err;
+}
+
+static int iso_out(struct i915_gem_context *ctx,
+ struct intel_engine_cs *engine,
+ struct drm_i915_gem_object *obj,
+ u32 *ctl)
+{
+ struct i915_vma *batch, *vma;
+ struct i915_request *rq;
+ u32 *cs;
+ int err;
+ int i;
+
+ batch = create_vma(ctx->vm, 64 << 10);
+ if (IS_ERR(batch))
+ return PTR_ERR(batch);
+
+ vma = i915_vma_instance(obj, ctx->vm, NULL);
+ if (IS_ERR(vma)) {
+ err = PTR_ERR(vma);
+ goto err_batch;
+ }
+
+ err = i915_vma_pin(batch, 0, 0, PIN_USER);
+ if (err)
+ goto err_batch;
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER);
+ if (err)
+ goto err_unpin_batch;
+
+ cs = i915_gem_object_pin_map(batch->obj, I915_MAP_WC);
+ if (IS_ERR(cs)) {
+ err = PTR_ERR(cs);
+ goto err_vma;
+ }
+
+ for (i = 0; i < 1024; i++) {
+ u64 addr = vma->node.start + (4 * i + 3) * sizeof(u32);
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8;
+ *cs++ = ctl[4 * i + 0];
+ *cs++ = lower_32_bits(addr);
+ *cs++ = upper_32_bits(addr);
+ }
+ *cs++ = MI_BATCH_BUFFER_END;
+
+ i915_gem_object_flush_map(obj);
+ i915_gem_object_unpin_map(obj);
+
+ rq = igt_request_alloc(ctx, engine);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_vma;
+ }
+
+ i915_vma_lock(vma);
+ err = i915_request_await_object(rq, vma->obj, true);
+ if (err == 0)
+ err = i915_vma_move_to_active(vma, rq, EXEC_OBJECT_WRITE);
+ i915_vma_unlock(vma);
+ if (err)
+ goto err_rq;
+
+ i915_vma_lock(vma);
+ err = i915_request_await_object(rq, batch->obj, false);
+ if (err == 0)
+ err = i915_vma_move_to_active(batch, rq, 0);
+ i915_vma_unlock(vma);
+ if (err)
+ goto err_rq;
+
+ err = engine->emit_bb_start(rq, batch->node.start, batch->node.size, 0);
+
+err_rq:
+ i915_request_add(rq);
+err_vma:
+ i915_vma_unpin(vma);
+err_unpin_batch:
+ i915_vma_unpin(batch);
+err_batch:
+ i915_vma_put(batch);
+ return err;
+}
+
+static bool is_timestamp(struct drm_i915_private *i915, u32 x)
+{
+ struct intel_engine_cs *engine;
+
+ for_each_uabi_engine(engine, i915) {
+ if (x == engine->mmio_base + 0x358)
+ return true;
+
+ if (x == engine->mmio_base + 0x35c)
+ return true;
+
+ if (x == engine->mmio_base + 0x3a8)
+ return true;
+ }
+
+ return false;
+}
+
+static bool is_whitelist(struct drm_i915_private *i915, u32 x)
+{
+ struct intel_engine_cs *engine;
+
+ for_each_uabi_engine(engine, i915) {
+ const struct i915_wa_list *w = &engine->whitelist;
+ int i;
+
+ for (i = 0; i < w->count; i++) {
+ if (x == i915_mmio_reg_offset(w->list[i].reg))
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static u32 random_reg(struct drm_i915_private *i915,
+ struct rnd_state *prng)
+{
+ u32 x;
+
+ /*
+ * Pick any u32 aligned value that is not known to a free running
+ * counter (e.g. a timestamp).
+ */
+ do {
+ x = prandom_u32_state(prng) % 10000 * sizeof(u32);
+ if (!is_timestamp(i915, x) && !is_whitelist(i915, x))
+ return x;
+ } while (1);
+}
+
+static int igt_reg_isolation(void *arg)
+{
+ struct drm_i915_private *i915 = arg;
+ struct i915_gem_context *ctx_a, *ctx_b;
+ struct drm_i915_gem_object *obj;
+ struct intel_engine_cs *engine;
+ struct igt_live_test t;
+ I915_RND_STATE(prng);
+ struct file *file;
+ u32 *ctl;
+ int err;
+ int i;
+
+ if (INTEL_GEN(i915) < 8) /* for LRM/SRM */
+ return 0;
+
+ /*
+ * No state that we can write to from our context should be
+ * observable by another.
+ */
+
+ file = mock_file(i915);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ err = igt_live_test_begin(&t, i915, __func__, "");
+ if (err)
+ goto out_file;
+
+ ctx_a = live_context(i915, file);
+ if (IS_ERR(ctx_a)) {
+ err = PTR_ERR(ctx_a);
+ goto out_file;
+ }
+
+ ctx_b = live_context(i915, file);
+ if (IS_ERR(ctx_b)) {
+ err = PTR_ERR(ctx_b);
+ goto out_file;
+ }
+
+ obj = i915_gem_object_create_internal(i915, 16 * 1024);
+ if (IS_ERR(obj)) {
+ err = PTR_ERR(obj);
+ goto out_file;
+ }
+
+ ctl = i915_gem_object_pin_map(obj, I915_MAP_WC);
+ if (IS_ERR(ctl)) {
+ err = PTR_ERR(ctl);
+ goto out_obj;
+ }
+
+ for (i = 0; i < 1024; i++) {
+ ctl[4 * i + 0] = random_reg(i915, &prng);
+ ctl[4 * i + 1] = prandom_u32_state(&prng); /* poison */
+ ctl[4 * i + 2] = 0; /* before, ctx_a */
+ ctl[4 * i + 3] = 0; /* after, ctx_b */
+ }
+ i915_gem_object_flush_map(obj);
+
+ for_each_uabi_engine(engine, i915) {
+ if (!engine->default_state)
+ continue;
+
+ err = iso_in(ctx_a, engine, obj, ctl);
+ if (err)
+ break;
+
+ err = iso_out(ctx_b, engine, obj, ctl);
+ if (err)
+ break;
+
+ err = i915_gem_object_wait(obj,
+ I915_WAIT_ALL |
+ I915_WAIT_INTERRUPTIBLE,
+ HZ / 2);
+ if (err)
+ break;
+
+ for (i = 0; i < 1024; i++) {
+ u32 in, out;
+
+ if (ctl[4 * i + 2] == ctl[4 * i + 3])
+ continue;
+
+ /*
+ * If there are more bits in common with the poison
+ * than the original, declare victory!
+ */
+ in = ctl[4 * i + 2] ^ ctl[4 * i + 1];
+ out = ctl[4 * i + 3] ^ ctl[4 * i + 1];
+ if (hweight32(out) < hweight32(in)) {
+ pr_err("%s[%d]: poisoned? reg %x with %08x, in:%08x, out:%08x\n",
+ engine->name, i,
+ ctl[4 * i + 0],
+ ctl[4 * i + 1],
+ ctl[4 * i + 2],
+ ctl[4 * i + 3]);
+ err = -EINVAL;
+ }
+ }
+ if (err)
+ break;
+ }
+
+ i915_gem_object_unpin_map(obj);
+ if (igt_live_test_end(&t))
+ err = -EIO;
+
+out_obj:
+ i915_gem_object_put(obj);
+out_file:
+ fput(file);
+ return err;
+}
+
static bool skip_unused_engines(struct intel_context *ce, void *data)
{
return !ce->state;
@@ -2000,6 +2354,7 @@ int i915_gem_context_live_selftests(struct drm_i915_private *i915)
SUBTEST(igt_ctx_sseu),
SUBTEST(igt_shared_ctx_exec),
SUBTEST(igt_vm_isolation),
+ SUBTEST(igt_reg_isolation),
};
if (intel_gt_is_wedged(&i915->gt))
--
2.20.1
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