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drm/ttm: add multihop infrastrucutre (v3) 

Currently drivers get called to move a buffer, but if they have to
move it temporarily through another space (SYSTEM->VRAM via TT)
then they can end up with a lot of ttm->driver->ttm call stacks,
if the temprorary space moves requires eviction.

Instead of letting the driver do all the placement/space for the
temporary, allow it to report back (-EMULTIHOP) and a placement (hop)
to the move code, which will then do the temporary move, and the
correct placement move afterwards.

This removes a lot of code from drivers, at the expense of
adding some midlayering. I've some further ideas on how to turn
it inside out, but I think this is a good solution to the call
stack problems.

v2: separate out the driver patches, add WARN for getting
MULTHOP in paths we shouldn't (Daniel)
v3: use memset (Christian)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: hristian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109005432.861936-2-airlied@gmail.com
This commit is contained in:
Dave Airlie 2020-10-29 13:58:52 +10:00
parent 2dcab875e7
commit ebdf565169
8 changed files with 83 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
View File

@ -656,7 +656,8 @@ static bool amdgpu_mem_visible(struct amdgpu_device *adev,
*/
static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_mem)
struct ttm_resource *new_mem,
struct ttm_place *hop)
{
struct amdgpu_device *adev;
struct amdgpu_bo *abo;

3
drivers/gpu/drm/drm_gem_vram_helper.c
View File

@ -955,7 +955,8 @@ static void bo_driver_delete_mem_notify(struct ttm_buffer_object *bo)
static int bo_driver_move(struct ttm_buffer_object *bo,
bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_mem)
struct ttm_resource *new_mem,
struct ttm_place *hop)
{
struct drm_gem_vram_object *gbo;

3
drivers/gpu/drm/nouveau/nouveau_bo.c
View File

@ -1023,7 +1023,8 @@ nouveau_bo_vm_cleanup(struct ttm_buffer_object *bo,
static int
nouveau_bo_move(struct ttm_buffer_object *bo, bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_reg)
struct ttm_resource *new_reg,
struct ttm_place *hop)
{
struct nouveau_drm *drm = nouveau_bdev(bo->bdev);
struct nouveau_bo *nvbo = nouveau_bo(bo);

3
drivers/gpu/drm/qxl/qxl_ttm.c
View File

@ -140,7 +140,8 @@ static void qxl_bo_move_notify(struct ttm_buffer_object *bo,
static int qxl_bo_move(struct ttm_buffer_object *bo, bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_mem)
struct ttm_resource *new_mem,
struct ttm_place *hop)
{
struct ttm_resource *old_mem = &bo->mem;
int ret;

3
drivers/gpu/drm/radeon/radeon_ttm.c
View File

@ -303,7 +303,8 @@ static int radeon_move_ram_vram(struct ttm_buffer_object *bo,
static int radeon_bo_move(struct ttm_buffer_object *bo, bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_mem)
struct ttm_resource *new_mem,
struct ttm_place *hop)
{
struct radeon_device *rdev;
struct radeon_bo *rbo;

74
drivers/gpu/drm/ttm/ttm_bo.c
View File

@ -231,7 +231,8 @@ EXPORT_SYMBOL(ttm_bo_bulk_move_lru_tail);
static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
struct ttm_resource *mem, bool evict,
struct ttm_operation_ctx *ctx)
struct ttm_operation_ctx *ctx,
struct ttm_place *hop)
{
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_resource_manager *old_man = ttm_manager_type(bdev, bo->mem.mem_type);
@ -259,9 +260,12 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
}
}
ret = bdev->driver->move(bo, evict, ctx, mem);
if (ret)
ret = bdev->driver->move(bo, evict, ctx, mem, hop);
if (ret) {
if (ret == -EMULTIHOP)
return ret;
goto out_err;
}
ctx->bytes_moved += bo->num_pages << PAGE_SHIFT;
return 0;
@ -566,8 +570,11 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_resource evict_mem;
struct ttm_placement placement;
struct ttm_place hop;
int ret = 0;
memset(&hop, 0, sizeof(hop));
dma_resv_assert_held(bo->base.resv);
placement.num_placement = 0;
@ -596,8 +603,9 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
goto out;
}
ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, ctx);
ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, ctx, &hop);
if (unlikely(ret)) {
WARN(ret == -EMULTIHOP, "Unexpected multihop in eviction - likely driver bug\n");
if (ret != -ERESTARTSYS)
pr_err("Buffer eviction failed\n");
ttm_resource_free(bo, &evict_mem);
@ -936,15 +944,45 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
}
EXPORT_SYMBOL(ttm_bo_mem_space);
static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,
struct ttm_resource *mem,
struct ttm_operation_ctx *ctx,
struct ttm_place *hop)
{
struct ttm_placement hop_placement;
int ret;
struct ttm_resource hop_mem = *mem;
hop_mem.mm_node = NULL;
hop_mem.mem_type = TTM_PL_SYSTEM;
hop_mem.placement = 0;
hop_placement.num_placement = hop_placement.num_busy_placement = 1;
hop_placement.placement = hop_placement.busy_placement = hop;
/* find space in the bounce domain */
ret = ttm_bo_mem_space(bo, &hop_placement, &hop_mem, ctx);
if (ret)
return ret;
/* move to the bounce domain */
ret = ttm_bo_handle_move_mem(bo, &hop_mem, false, ctx, NULL);
if (ret)
return ret;
return 0;
}
static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
struct ttm_placement *placement,
struct ttm_operation_ctx *ctx)
{
int ret = 0;
struct ttm_place hop;
struct ttm_resource mem;
dma_resv_assert_held(bo->base.resv);
memset(&hop, 0, sizeof(hop));
mem.num_pages = bo->num_pages;
mem.size = mem.num_pages << PAGE_SHIFT;
mem.page_alignment = bo->mem.page_alignment;
@ -954,12 +992,25 @@ static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
/*
* Determine where to move the buffer.
*
* If driver determines move is going to need
* an extra step then it will return -EMULTIHOP
* and the buffer will be moved to the temporary
* stop and the driver will be called to make
* the second hop.
*/
bounce:
ret = ttm_bo_mem_space(bo, placement, &mem, ctx);
if (ret)
goto out_unlock;
ret = ttm_bo_handle_move_mem(bo, &mem, false, ctx);
out_unlock:
return ret;
ret = ttm_bo_handle_move_mem(bo, &mem, false, ctx, &hop);
if (ret == -EMULTIHOP) {
ret = ttm_bo_bounce_temp_buffer(bo, &mem, ctx, &hop);
if (ret)
return ret;
/* try and move to final place now. */
goto bounce;
}
if (ret)
ttm_resource_free(bo, &mem);
return ret;
@ -1432,15 +1483,20 @@ int ttm_bo_swapout(struct ttm_operation_ctx *ctx)
if (bo->mem.mem_type != TTM_PL_SYSTEM) {
struct ttm_operation_ctx ctx = { false, false };
struct ttm_resource evict_mem;
struct ttm_place hop;
memset(&hop, 0, sizeof(hop));
evict_mem = bo->mem;
evict_mem.mm_node = NULL;
evict_mem.placement = 0;
evict_mem.mem_type = TTM_PL_SYSTEM;
ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, &ctx);
if (unlikely(ret != 0))
ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, &ctx, &hop);
if (unlikely(ret != 0)) {
WARN(ret == -EMULTIHOP, "Unexpected multihop in swaput - likely driver bug.\n");
goto out;
}
}
/**

3
drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
View File

@ -695,7 +695,8 @@ static void vmw_swap_notify(struct ttm_buffer_object *bo)
static int vmw_move(struct ttm_buffer_object *bo,
bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_mem)
struct ttm_resource *new_mem,
struct ttm_place *hop)
{
struct ttm_resource_manager *old_man = ttm_manager_type(bo->bdev, bo->mem.mem_type);
struct ttm_resource_manager *new_man = ttm_manager_type(bo->bdev, new_mem->mem_type);

7
include/drm/ttm/ttm_bo_driver.h
View File

@ -121,6 +121,8 @@ struct ttm_bo_driver {
* Return the bo flags for a buffer which is not mapped to the hardware.
* These will be placed in proposed_flags so that when the move is
* finished, they'll end up in bo->mem.flags
* This should not cause multihop evictions, and the core will warn
* if one is proposed.
*/
void (*evict_flags)(struct ttm_buffer_object *bo,
@ -134,12 +136,15 @@ struct ttm_bo_driver {
* the graphics address space
* @ctx: context for this move with parameters
* @new_mem: the new memory region receiving the buffer
@ @hop: placement for driver directed intermediate hop
*
* Move a buffer between two memory regions.
* Returns errno -EMULTIHOP if driver requests a hop
*/
int (*move)(struct ttm_buffer_object *bo, bool evict,
struct ttm_operation_ctx *ctx,
struct ttm_resource *new_mem);
struct ttm_resource *new_mem,
struct ttm_place *hop);
/**
* struct ttm_bo_driver_member verify_access