drm/amdkfd: reserve the BO before validating it

Fix a warning.

v2: Avoid unmapping attachment repeatedly when ERESTARTSYS.

v3: Lock the BO before accessing ttm->sg to avoid race conditions.(Felix)

[   41.708711] WARNING: CPU: 0 PID: 1463 at drivers/gpu/drm/ttm/ttm_bo.c:846 ttm_bo_validate+0x146/0x1b0 [ttm]
[   41.708989] Call Trace:
[   41.708992]  <TASK>
[   41.708996]  ? show_regs+0x6c/0x80
[   41.709000]  ? ttm_bo_validate+0x146/0x1b0 [ttm]
[   41.709008]  ? __warn+0x93/0x190
[   41.709014]  ? ttm_bo_validate+0x146/0x1b0 [ttm]
[   41.709024]  ? report_bug+0x1f9/0x210
[   41.709035]  ? handle_bug+0x46/0x80
[   41.709041]  ? exc_invalid_op+0x1d/0x80
[   41.709048]  ? asm_exc_invalid_op+0x1f/0x30
[   41.709057]  ? amdgpu_amdkfd_gpuvm_dmaunmap_mem+0x2c/0x80 [amdgpu]
[   41.709185]  ? ttm_bo_validate+0x146/0x1b0 [ttm]
[   41.709197]  ? amdgpu_amdkfd_gpuvm_dmaunmap_mem+0x2c/0x80 [amdgpu]
[   41.709337]  ? srso_alias_return_thunk+0x5/0x7f
[   41.709346]  kfd_mem_dmaunmap_attachment+0x9e/0x1e0 [amdgpu]
[   41.709467]  amdgpu_amdkfd_gpuvm_dmaunmap_mem+0x56/0x80 [amdgpu]
[   41.709586]  kfd_ioctl_unmap_memory_from_gpu+0x1b7/0x300 [amdgpu]
[   41.709710]  kfd_ioctl+0x1ec/0x650 [amdgpu]
[   41.709822]  ? __pfx_kfd_ioctl_unmap_memory_from_gpu+0x10/0x10 [amdgpu]
[   41.709945]  ? srso_alias_return_thunk+0x5/0x7f
[   41.709949]  ? tomoyo_file_ioctl+0x20/0x30
[   41.709959]  __x64_sys_ioctl+0x9c/0xd0
[   41.709967]  do_syscall_64+0x3f/0x90
[   41.709973]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Fixes: 101b810 ("drm/amdkfd: Move dma unmapping after TLB flush")
Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Lang Yu

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h

@@ -303,7 +303,7 @@ int amdgpu_amdkfd_gpuvm_map_memory_to_gpu(struct amdgpu_device *adev,
 					  struct kgd_mem *mem, void *drm_priv);
 int amdgpu_amdkfd_gpuvm_unmap_memory_from_gpu(
 		struct amdgpu_device *adev, struct kgd_mem *mem, void *drm_priv);
-void amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void *drm_priv);
+int amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void *drm_priv);
 int amdgpu_amdkfd_gpuvm_sync_memory(
 		struct amdgpu_device *adev, struct kgd_mem *mem, bool intr);
 int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct kgd_mem *mem,

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

@@ -2085,21 +2085,35 @@ int amdgpu_amdkfd_gpuvm_map_memory_to_gpu(
 	return ret;
 }
 
-void amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void *drm_priv)
+int amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void *drm_priv)
 {
 	struct kfd_mem_attachment *entry;
 	struct amdgpu_vm *vm;
+	int ret;
 
 	vm = drm_priv_to_vm(drm_priv);
 
 	mutex_lock(&mem->lock);
 
+	ret = amdgpu_bo_reserve(mem->bo, true);
+	if (ret)
+		goto out;
+
 	list_for_each_entry(entry, &mem->attachments, list) {
-		if (entry->bo_va->base.vm == vm)
-			kfd_mem_dmaunmap_attachment(mem, entry);
+		if (entry->bo_va->base.vm != vm)
+			continue;
+		if (entry->bo_va->base.bo->tbo.ttm &&
+		    !entry->bo_va->base.bo->tbo.ttm->sg)
+			continue;
+
+		kfd_mem_dmaunmap_attachment(mem, entry);
 	}
 
+	amdgpu_bo_unreserve(mem->bo);
+out:
 	mutex_unlock(&mem->lock);
+
+	return ret;
 }
 
 int amdgpu_amdkfd_gpuvm_unmap_memory_from_gpu(

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

@@ -1442,7 +1442,9 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
 			kfd_flush_tlb(peer_pdd, TLB_FLUSH_HEAVYWEIGHT);
 
 		/* Remove dma mapping after tlb flush to avoid IO_PAGE_FAULT */
-		amdgpu_amdkfd_gpuvm_dmaunmap_mem(mem, peer_pdd->drm_priv);
+		err = amdgpu_amdkfd_gpuvm_dmaunmap_mem(mem, peer_pdd->drm_priv);
+		if (err)
+			goto sync_memory_failed;
 	}
 
 	mutex_unlock(&p->mutex);