[PATCH v2] gpu: GPU_BUDDY_KUNIT_TEST should not select GPU_BUDDY

[Geert Uytterhoeven <geert@linux-m68k.org>]

Enabling a (modular) test should not silently enable additional kernel
functionality, as that may increase the attack vector for a product.

Fix this by reverting the select to a dependency.  Make sure the GPU
buddy allocator can be tested without enabling another driver that uses
DRM_BUDDY by making GPU_BUDDY visible if KUNIT is enabled.

The page based buddy allocator for GPU memory is only used by DRM.
Hence add a dependency on DRM to GPU_BUDDY, to prevent asking the user
about this code when configuring a kernel without DRM support.

Update drivers/gpu/tests/.kunitconfig accordingly.

Fixes: 8fe3fc37564920ae ("gpu: Fix dependencies in CONFIG_GPU_BUDDY_KUNIT_TEST")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - Update drivers/gpu/tests/.kunitconfig.
---
 drivers/gpu/Kconfig            | 5 +++--
 drivers/gpu/tests/.kunitconfig | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/Kconfig b/drivers/gpu/Kconfig
index 3bcf08260d73a782..d881ab6f7a006a3b 100644
--- a/drivers/gpu/Kconfig
+++ b/drivers/gpu/Kconfig
@@ -1,14 +1,15 @@
 # SPDX-License-Identifier: GPL-2.0
 
 config GPU_BUDDY
-       bool
+       bool "Page based buddy allocator for GPU memory" if KUNIT
+       depends on DRM || COMPILE_TEST
        help
          A page based buddy allocator for GPU memory.
 
 config GPU_BUDDY_KUNIT_TEST
        tristate "KUnit tests for GPU buddy allocator" if !KUNIT_ALL_TESTS
        depends on KUNIT
-       select GPU_BUDDY
+       depends on GPU_BUDDY
        default KUNIT_ALL_TESTS
        help
          KUnit tests for the GPU buddy allocator.
diff --git a/drivers/gpu/tests/.kunitconfig b/drivers/gpu/tests/.kunitconfig
index fd611b3dfe09c4f6..c103afc02c9ede16 100644
--- a/drivers/gpu/tests/.kunitconfig
+++ b/drivers/gpu/tests/.kunitconfig
@@ -1,2 +1,4 @@
 CONFIG_KUNIT=y
+CONFIG_COMPILE_TEST=y
+CONFIG_GPU_BUDDY=y
 CONFIG_GPU_BUDDY_KUNIT_TEST=y
-- 
2.43.0