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

[Christian König]

Am 30.01.24 um 21:08 schrieb 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>

Reviewed-by: Christian König <christian.koenig 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)
>