On 16/09/2021 10:03, Thomas Hellström wrote:
On Thu, 2021-09-16 at 08:55 +0200, Christian König wrote:
Am 15.09.21 um 20:59 schrieb Matthew Auld:
In commit:
commit 667a50db0477d47fdff01c666f5ee1ce26b5264c
Author: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Date: Fri Jan 3 11:17:18 2014 +0100
drm/ttm: Refuse to fault (prime-) imported pages
we introduced the restriction that imported pages should not be
directly
mappable through TTM(this also extends to userptr). In the next
patch we
want to introduce a shmem_tt backend, which should follow all the
existing rules with TTM_PAGE_FLAG_EXTERNAL, since it will need to
handle
swapping itself, but with the above mapping restriction lifted.
Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 ++++--
include/drm/ttm/ttm_tt.h | 7 +++++++
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c
b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 708390588c7c..fd6e18f12f50 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -163,8 +163,10 @@ vm_fault_t ttm_bo_vm_reserve(struct
ttm_buffer_object *bo,
* (if at all) by redirecting mmap to the exporter.
*/
if (bo->ttm && (bo->ttm->page_flags &
TTM_PAGE_FLAG_EXTERNAL)) {
- dma_resv_unlock(bo->base.resv);
- return VM_FAULT_SIGBUS;
+ if (!(bo->ttm->page_flags &
TTM_PAGE_FLAG_EXTERNAL_MAPPABLE)) {
I saw there was previously a thought about testing for ttm_bo_type_sg
here. Was that a dead end?
I guess the issue was userptr, which is also EXTERNAL and needs to be
rejected here, but underneath it's not type_sg.
Just having an explicit MAPPABLE flag or similar seemed the more
flexible approach? Happy to try out other ideas.
Thanks,
Thomas
