[PATCH v2 3/3] drm/amdgpu: Workaround IOMMU driver bug

[Felix Kuehling]

The intel IOMMU driver causes kernel oopses or internal errors flooding
kernel log when mapping larger SG tables. Limiting the size of userptr BOs
to 6GB seems to avoid this.

Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 2b8b89535198..3becf9d9f8fd 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1409,6 +1409,9 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 		domain = alloc_domain = AMDGPU_GEM_DOMAIN_GTT;
 		alloc_flags = 0;
 	} else if (flags & KFD_IOC_ALLOC_MEM_FLAGS_USERPTR) {
+		/* workaround IOMMU driver bug */
+		if (size >= (6ULL << 30))
+			return -ENOMEM;
 		domain = AMDGPU_GEM_DOMAIN_GTT;
 		alloc_domain = AMDGPU_GEM_DOMAIN_CPU;
 		alloc_flags = AMDGPU_GEM_CREATE_PREEMPTIBLE;
-- 
2.31.1