[PATCH 6.6 086/567] drm/amdgpu: keep vga memory on MacBooks with switchable graphics

Greg Kroah-Hartman
2026-03-23T14:55:38Z

6.6-stable review patch. If anyone has any objections, please let me know.

------------------

From: Alex Deucher <alexander.deucher@amd.com>

[ Upstream commit 096bb75e13cc508d3915b7604e356bcb12b17766 ]

On Intel MacBookPros with switchable graphics, when the iGPU
is enabled, the address of VRAM gets put at 0 in the dGPU's
virtual address space. This is non-standard and seems to cause
issues with the cursor if it ends up at 0. We have the framework
to reserve memory at 0 in the address space, so enable it here if
the vram start address is 0.

Reviewed-and-tested-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4302
Cc: stable@vger.kernel.org
Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
index 7d120d4175499..8cb192636368f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
@@ -728,6 +728,16 @@ void amdgpu_gmc_get_vbios_allocations(struct amdgpu_device *adev)
case CHIP_RENOIR:
adev->mman.keep_stolen_vga_memory = true;
break;
+ case CHIP_POLARIS10:
+ case CHIP_POLARIS11:
+ case CHIP_POLARIS12:
+ /* MacBookPros with switchable graphics put VRAM at 0 when
+ * the iGPU is enabled which results in cursor issues if
+ * the cursor ends up at 0. Reserve vram at 0 in that case.
+ */
+ if (adev->gmc.vram_start == 0)
+ adev->mman.keep_stolen_vga_memory = true;
+ break;
default:
adev->mman.keep_stolen_vga_memory = false;
break;
--
2.51.0