Am 21.06.20 um 08:03 schrieb Andrey Grodzovsky:
On device removal reroute all CPU mappings to dummy page per drm_file
instance or imported GEM object.

Signed-off-by: Andrey Grodzovsky <andrey.grodzov...@amd.com>
---
  drivers/gpu/drm/ttm/ttm_bo_vm.c | 65 ++++++++++++++++++++++++++++++++++++-----
  1 file changed, 57 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 389128b..2f8bf5e 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -35,6 +35,8 @@
  #include <drm/ttm/ttm_bo_driver.h>
  #include <drm/ttm/ttm_placement.h>
  #include <drm/drm_vma_manager.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
  #include <linux/mm.h>
  #include <linux/pfn_t.h>
  #include <linux/rbtree.h>
@@ -328,19 +330,66 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
        pgprot_t prot;
        struct ttm_buffer_object *bo = vma->vm_private_data;
        vm_fault_t ret;
+       int idx;
+       struct drm_device *ddev = bo->base.dev;
- ret = ttm_bo_vm_reserve(bo, vmf);
-       if (ret)
-               return ret;
+       if (drm_dev_enter(ddev, &idx)) {

Better do this like if (!drm_dev_enter(...)) return ttm_bo_vm_dummy(..);

This way you can move all the dummy fault handling into a separate function without cluttering this one here to much.

Christian.

+               ret = ttm_bo_vm_reserve(bo, vmf);
+               if (ret)
+                       goto exit;
+
+               prot = vma->vm_page_prot;
- prot = vma->vm_page_prot;
-       ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
-       if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
+               ret = ttm_bo_vm_fault_reserved(vmf, prot, 
TTM_BO_VM_NUM_PREFAULT);
+               if (ret == VM_FAULT_RETRY && !(vmf->flags & 
FAULT_FLAG_RETRY_NOWAIT))
+                       goto exit;
+
+               dma_resv_unlock(bo->base.resv);
+
+exit:
+               drm_dev_exit(idx);
                return ret;
+       } else {
- dma_resv_unlock(bo->base.resv);
+               struct drm_file *file = NULL;
+               struct page *dummy_page = NULL;
+               int handle;
- return ret;
+               /* We are faulting on imported BO from dma_buf */
+               if (bo->base.dma_buf && bo->base.import_attach) {
+                       dummy_page = bo->base.dummy_page;
+               /* We are faulting on non imported BO, find drm_file owning the 
BO*/
+               } else {
+                       struct drm_gem_object *gobj;
+
+                       mutex_lock(&ddev->filelist_mutex);
+                       list_for_each_entry(file, &ddev->filelist, lhead) {
+                               spin_lock(&file->table_lock);
+                               idr_for_each_entry(&file->object_idr, gobj, 
handle) {
+                                       if (gobj == &bo->base) {
+                                               dummy_page = file->dummy_page;
+                                               break;
+                                       }
+                               }
+                               spin_unlock(&file->table_lock);
+                       }
+                       mutex_unlock(&ddev->filelist_mutex);
+               }
+
+               if (dummy_page) {
+                       /*
+                        * Let do_fault complete the PTE install e.t.c using 
vmf->page
+                        *
+                        * TODO - should i call free_page somewhere ?
+                        */
+                       get_page(dummy_page);
+                       vmf->page = dummy_page;
+                       return 0;
+               } else {
+                       return VM_FAULT_SIGSEGV;
+               }
+       }
  }
  EXPORT_SYMBOL(ttm_bo_vm_fault);

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