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authorThomas Hellström <thomas.hellstrom@linux.intel.com>2021-06-02 11:38:13 +0300
committerThomas Hellström <thomas.hellstrom@linux.intel.com>2021-06-07 17:07:08 +0300
commita3be8cd70fec2aa8913b59c9026031205c29df28 (patch)
tree6b6bd93da399fd77d6ca54d4c045e73cf7a57c3a /drivers/gpu/drm/ttm/ttm_bo_util.c
parent053c57696cb99c35859e9e9cc58c7d00e434d956 (diff)
downloadlinux-a3be8cd70fec2aa8913b59c9026031205c29df28.tar.xz
drm/ttm: Document and optimize ttm_bo_pipeline_gutting()
If the bo is idle when calling ttm_bo_pipeline_gutting(), we unnecessarily create a ghost object and push it out to delayed destroy. Fix this by adding a path for idle, and document the function. Also avoid having the bo end up in a bad state vulnerable to user-space triggered kernel BUGs if the call to ttm_tt_create() fails. Finally reuse ttm_bo_pipeline_gutting() in ttm_bo_evict(). Cc: Christian König <christian.koenig@amd.com> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://lore.kernel.org/r/20210602083818.241793-7-thomas.hellstrom@linux.intel.com
Diffstat (limited to 'drivers/gpu/drm/ttm/ttm_bo_util.c')
-rw-r--r--drivers/gpu/drm/ttm/ttm_bo_util.c54
1 files changed, 49 insertions, 5 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 3161adb5903c..1d25994411a0 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -566,26 +566,70 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
}
EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
+/**
+ * ttm_bo_pipeline_gutting - purge the contents of a bo
+ * @bo: The buffer object
+ *
+ * Purge the contents of a bo, async if the bo is not idle.
+ * After a successful call, the bo is left unpopulated in
+ * system placement. The function may wait uninterruptible
+ * for idle on OOM.
+ *
+ * Return: 0 if successful, negative error code on failure.
+ */
int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
{
static const struct ttm_place sys_mem = { .mem_type = TTM_PL_SYSTEM };
struct ttm_buffer_object *ghost;
+ struct ttm_tt *ttm;
int ret;
- ret = ttm_buffer_object_transfer(bo, &ghost);
+ /* If already idle, no need for ghost object dance. */
+ ret = ttm_bo_wait(bo, false, true);
+ if (ret != -EBUSY) {
+ if (!bo->ttm) {
+ /* See comment below about clearing. */
+ ret = ttm_tt_create(bo, true);
+ if (ret)
+ return ret;
+ } else {
+ ttm_tt_unpopulate(bo->bdev, bo->ttm);
+ if (bo->type == ttm_bo_type_device)
+ ttm_tt_mark_for_clear(bo->ttm);
+ }
+ ttm_resource_free(bo, &bo->resource);
+ return ttm_resource_alloc(bo, &sys_mem, &bo->resource);
+ }
+
+ /*
+ * We need an unpopulated ttm_tt after giving our current one,
+ * if any, to the ghost object. And we can't afford to fail
+ * creating one *after* the operation. If the bo subsequently gets
+ * resurrected, make sure it's cleared (if ttm_bo_type_device)
+ * to avoid leaking sensitive information to user-space.
+ */
+
+ ttm = bo->ttm;
+ bo->ttm = NULL;
+ ret = ttm_tt_create(bo, true);
+ swap(bo->ttm, ttm);
if (ret)
return ret;
+ ret = ttm_buffer_object_transfer(bo, &ghost);
+ if (ret) {
+ ttm_tt_destroy(bo->bdev, ttm);
+ return ret;
+ }
+
ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
/* Last resort, wait for the BO to be idle when we are OOM */
if (ret)
ttm_bo_wait(bo, false, false);
- ret = ttm_resource_alloc(bo, &sys_mem, &bo->resource);
- bo->ttm = NULL;
-
dma_resv_unlock(&ghost->base._resv);
ttm_bo_put(ghost);
+ bo->ttm = ttm;
- return ret;
+ return ttm_resource_alloc(bo, &sys_mem, &bo->resource);
}