[PATCH 1/2] drm/amdgpu: Reduce VA_RESERVED_BOTTOM to 64KB

[Felix Kuehling]

The reservation is there to catch NULL pointer dereferences from the
GPU. Reduce the size to 64KB to make sure that shared virtual address
programming models can map all CPU-accessible virtual addresses for GPU
access. This is also the default for CPU virtual address mappings as
seen in /proc/sys/vm/mmap_min_addr.

Signed-off-by: Felix Kuehling <felix.kuehling at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
index 666698a57192..2c4053b29bb3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
@@ -135,10 +135,10 @@ struct amdgpu_mem_stats;
 #define AMDGPU_IS_MMHUB0(x) ((x) >= AMDGPU_MMHUB0_START && (x) < AMDGPU_MMHUB1_START)
 #define AMDGPU_IS_MMHUB1(x) ((x) >= AMDGPU_MMHUB1_START && (x) < AMDGPU_MAX_VMHUBS)
 
-/* Reserve 2MB at top/bottom of address space for kernel use */
+/* Reserve space at top/bottom of address space for kernel use */
 #define AMDGPU_VA_RESERVED_CSA_SIZE		(2ULL << 20)
 #define AMDGPU_VA_RESERVED_SEQ64_SIZE		(2ULL << 20)
-#define AMDGPU_VA_RESERVED_BOTTOM		(2ULL << 20)
+#define AMDGPU_VA_RESERVED_BOTTOM		(1ULL << 16)
 #define AMDGPU_VA_RESERVED_TOP			(AMDGPU_VA_RESERVED_SEQ64_SIZE + \
 						 AMDGPU_VA_RESERVED_CSA_SIZE)
 
-- 
2.34.1