drm/i915: Wait for page_sizes_gtt in gtt selftest on CHV/BXT+VTD

VMA pinning to GGTT is now commited asynchronously in CHV / BXT+VDT
environments to avoid lock inversion among reservation_ww and cpu_hotplug
locks, the latter acquired from stop_machine().  Then,
vma->resource->page_sizes_gtt the test uses as shift count may still be
not populated (equal 0) after i915_vma_pin() returns.  Wait for VMA bind
completion in those cases to avoid shift-out-of-bounds kernel warnings and
the test case failing with -EBADSLT.

v2: Explain why VMA pinning is commited asynchronously on CHV/BXT+VTD
    (Krzysztof),
  - use more precise wording in commit description.

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Reviewed-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
Acked-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://lore.kernel.org/r/20251023082925.351307-8-janusz.krzysztofik@linux.intel.com

Author: jkrzyszt-intel

drivers/gpu/drm/i915/selftests/i915_gem_gtt.c

@@ -1118,6 +1118,10 @@ static int misaligned_case(struct i915_address_space *vm, struct intel_memory_re
 		goto err_put;
 	}
 
+	/* make sure page_sizes_gtt has been populated before use */
+	if (i915_is_ggtt(vm) && intel_vm_no_concurrent_access_wa(vm->i915))
+		i915_vma_wait_for_bind(vma);
+
 	expected_vma_size = round_up(size, 1 << (ffs(vma->resource->page_sizes_gtt) - 1));
 	expected_node_size = expected_vma_size;