Revert "drm/amdkfd: Relocate TBA/TMA to opposite side of VM hole"

That commit causes NULL pointer dereferences in dmesgs when
running applications using ROCm, including clinfo, blender,
and PyTorch, since v6.6.1. Revert it to fix blender again.

This reverts commit 96c211f1f9ef82183493f4ceed4e347b52849149.

Closes: https://github.com/ROCm/ROCm/issues/2596
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/2991
Reviewed-by: Jay Cornwall <[e-mail]>
Signed-off-by: Kaibo Ma <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c

···
 	pdd->gpuvm_limit =
 		pdd->dev->kfd->shared_resources.gpuvm_size - 1;
 
-	/* dGPUs: the reserved space for kernel
-	 * before SVM
-	 */
-	pdd->qpd.cwsr_base = SVM_CWSR_BASE;
-	pdd->qpd.ib_base = SVM_IB_BASE;
-
 	pdd->scratch_base = MAKE_SCRATCH_APP_BASE_VI();
 	pdd->scratch_limit = MAKE_SCRATCH_APP_LIMIT(pdd->scratch_base);
 }
···
 	pdd->lds_base = MAKE_LDS_APP_BASE_V9();
 	pdd->lds_limit = MAKE_LDS_APP_LIMIT(pdd->lds_base);
 
-	pdd->gpuvm_base = PAGE_SIZE;
+        /* Raven needs SVM to support graphic handle, etc. Leave the small
+         * reserved space before SVM on Raven as well, even though we don't
+         * have to.
+         * Set gpuvm_base and gpuvm_limit to CANONICAL addresses so that they
+         * are used in Thunk to reserve SVM.
+         */
+        pdd->gpuvm_base = SVM_USER_BASE;
 	pdd->gpuvm_limit =
 		pdd->dev->kfd->shared_resources.gpuvm_size - 1;
 
 	pdd->scratch_base = MAKE_SCRATCH_APP_BASE_V9();
 	pdd->scratch_limit = MAKE_SCRATCH_APP_LIMIT(pdd->scratch_base);
-
-	/*
-	 * Place TBA/TMA on opposite side of VM hole to prevent
-	 * stray faults from triggering SVM on these pages.
-	 */
-	pdd->qpd.cwsr_base = pdd->dev->kfd->shared_resources.gpuvm_size;
 }
 
 int kfd_init_apertures(struct kfd_process *process)
···
 					return -EINVAL;
 				}
 			}
+
+                        /* dGPUs: the reserved space for kernel
+                         * before SVM
+                         */
+                        pdd->qpd.cwsr_base = SVM_CWSR_BASE;
+                        pdd->qpd.ib_base = SVM_IB_BASE;
 		}
 
 		dev_dbg(kfd_device, "node id %u\n", id);