[PATCH v5 07/27] drm/amdgpu: Remap all page faults to per process dummy page.

[Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>]

On device removal reroute all CPU mappings to dummy page
per drm_file instance or imported GEM object.

v4:
Update for modified ttm_bo_vm_dummy_page

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index a785acc09f20..93163b220e46 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -49,6 +49,7 @@
 
 #include <drm/drm_debugfs.h>
 #include <drm/amdgpu_drm.h>
+#include <drm/drm_drv.h>
 
 #include "amdgpu.h"
 #include "amdgpu_object.h"
@@ -1982,18 +1983,28 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
 static vm_fault_t amdgpu_ttm_fault(struct vm_fault *vmf)
 {
 	struct ttm_buffer_object *bo = vmf->vma->vm_private_data;
+	struct drm_device *ddev = bo->base.dev;
 	vm_fault_t ret;
+	int idx;
 
 	ret = ttm_bo_vm_reserve(bo, vmf);
 	if (ret)
 		return ret;
 
-	ret = amdgpu_bo_fault_reserve_notify(bo);
-	if (ret)
-		goto unlock;
+	if (drm_dev_enter(ddev, &idx)) {
+		ret = amdgpu_bo_fault_reserve_notify(bo);
+		if (ret) {
+			drm_dev_exit(idx);
+			goto unlock;
+		}
 
-	ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
-				       TTM_BO_VM_NUM_PREFAULT, 1);
+		 ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
+						TTM_BO_VM_NUM_PREFAULT, 1);
+
+		 drm_dev_exit(idx);
+	} else {
+		ret = ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
+	}
 	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
 		return ret;
 
-- 
2.25.1