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drm/ttm: add TTM_TT_FLAG_EXTERNAL_MAPPABLE

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commit 667a50db04
Author: Thomas Hellstrom <thellstrom@vmware.com>
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.

v2(Christian):
  - Don't OR together EXTERNAL and EXTERNAL_MAPPABLE in the definition
    of EXTERNAL_MAPPABLE, just leave it the caller to handle this
    correctly, otherwise we might encounter subtle issues.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210929132629.353541-3-matthew.auld@intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>
This commit is contained in:
Matthew Auld 2021-09-29 14:26:29 +01:00 committed by Christian König
parent a5a3dd42fe
commit 49e7f76fc5
3 changed files with 23 additions and 5 deletions
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6
drivers/gpu/drm/ttm/ttm_bo_vm.c
View File

@ -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_TT_FLAG_EXTERNAL)) {
dma_resv_unlock(bo->base.resv);
return VM_FAULT_SIGBUS;
if (!(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL_MAPPABLE)) {
dma_resv_unlock(bo->base.resv);
return VM_FAULT_SIGBUS;
}
}
return 0;

3
drivers/gpu/drm/ttm/ttm_tt.c
View File

@ -84,6 +84,9 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc)
if (unlikely(bo->ttm == NULL))
return -ENOMEM;
WARN_ON(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL_MAPPABLE &&
!(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL));
return 0;
}

19
include/drm/ttm/ttm_tt.h
View File

@ -67,13 +67,26 @@ struct ttm_tt {
* Note that enum ttm_bo_type.ttm_bo_type_sg objects will always enable
* this flag.
*
* TTM_TT_FLAG_EXTERNAL_MAPPABLE: Same behaviour as
* TTM_TT_FLAG_EXTERNAL, but with the reduced restriction that it is
* still valid to use TTM to map the pages directly. This is useful when
* implementing a ttm_tt backend which still allocates driver owned
* pages underneath(say with shmem).
*
* Note that since this also implies TTM_TT_FLAG_EXTERNAL, the usage
* here should always be:
*
* page_flags = TTM_TT_FLAG_EXTERNAL |
* TTM_TT_FLAG_EXTERNAL_MAPPABLE;
*
* TTM_TT_FLAG_PRIV_POPULATED: TTM internal only. DO NOT USE. This is
* set by TTM after ttm_tt_populate() has successfully returned, and is
* then unset when TTM calls ttm_tt_unpopulate().
*/
#define TTM_TT_FLAG_SWAPPED (1 << 0)
#define TTM_TT_FLAG_ZERO_ALLOC (1 << 1)
#define TTM_TT_FLAG_EXTERNAL (1 << 2)
#define TTM_TT_FLAG_SWAPPED (1 << 0)
#define TTM_TT_FLAG_ZERO_ALLOC (1 << 1)
#define TTM_TT_FLAG_EXTERNAL (1 << 2)
#define TTM_TT_FLAG_EXTERNAL_MAPPABLE (1 << 3)
#define TTM_TT_FLAG_PRIV_POPULATED (1 << 31)
uint32_t page_flags;