On Sun, Jun 21, 2020 at 02:03:02AM -0400, Andrey Grodzovsky wrote:
On device removal reroute all CPU mappings to dummy page per drm_file instance or imported GEM object.
Signed-off-by: Andrey Grodzovsky andrey.grodzovsky@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)
Hm I think diff and code flow look a bit bad now. What about renaming the current function to __ttm_bo_vm_fault and then having something like the below:
ttm_bo_vm_fault(args) {
if (drm_dev_enter()) { __ttm_bo_vm_fault(args); drm_dev_exit(); } else { drm_gem_insert_dummy_pfn(); } }
I think drm_gem_insert_dummy_pfn(); should be portable across drivers, so another nice point to try to unifiy drivers as much as possible. -Daniel
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)) {
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);- } 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*/
Uh, we can't fish that out of the vma->vm_file pointer somehow? Or is that one all wrong? Doing this kind of list walk looks pretty horrible.
If the vma doesn't have the right pointer I guess next option is that we store the drm_file page in gem_bo->dummy_page, and replace it on first export. But that's going to be tricky to track ...
} 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 ?
Nah, instead don't call get_page. The page will be around as long as there's a reference for the drm_file or gem_bo, which is longer than any mmap. Otherwise yes this would like really badly.
*/get_page(dummy_page);vmf->page = dummy_page;return 0;} else {return VM_FAULT_SIGSEGV;
Hm that would be a kernel bug, wouldn't it? WARN_ON() required here imo. -Daniel
}- }
} EXPORT_SYMBOL(ttm_bo_vm_fault);
-- 2.7.4