In commit:
commit 667a50db0477d47fdff01c666f5ee1ce26b5264c 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 --- drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 ++++-- drivers/gpu/drm/ttm/ttm_tt.c | 3 +++ include/drm/ttm/ttm_tt.h | 19 ++++++++++++++++--- 3 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 950f4f132802..33680c94127c 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_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; diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c index 86f31fde6e35..7e83c00a3f48 100644 --- a/drivers/gpu/drm/ttm/ttm_tt.c +++ b/drivers/gpu/drm/ttm/ttm_tt.c @@ -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; }
diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h index f3ef568da651..5995b8ee1667 100644 --- a/include/drm/ttm/ttm_tt.h +++ b/include/drm/ttm/ttm_tt.h @@ -66,11 +66,24 @@ 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. */ -#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;