From: Dave Airlie <airlied@xxxxxxxxxx>
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)
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 3 +-
drivers/gpu/drm/drm_gem_vram_helper.c | 3 +-
drivers/gpu/drm/nouveau/nouveau_bo.c | 3 +-
drivers/gpu/drm/qxl/qxl_ttm.c | 3 +-
drivers/gpu/drm/radeon/radeon_ttm.c | 3 +-
drivers/gpu/drm/ttm/ttm_bo.c | 68 +++++++++++++++++++---
drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c | 3 +-
include/drm/ttm/ttm_bo_driver.h | 7 ++-
8 files changed, 77 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index c01c060e4ac5..ce0d82802333 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -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;
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 16d68c04ea5d..2cec7b1482b8 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -964,7 +964,8 @@ 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;
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index 8133377d865d..fee07b9d19ed 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -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);
diff --git a/drivers/gpu/drm/qxl/qxl_ttm.c b/drivers/gpu/drm/qxl/qxl_ttm.c
index a80d59634143..128c38c8a837 100644
--- a/drivers/gpu/drm/qxl/qxl_ttm.c
+++ b/drivers/gpu/drm/qxl/qxl_ttm.c
@@ -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;
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 95038ac3382e..29062dbea299 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -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;
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index e2a124b3affb..9f840f2a7836 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -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;
@@ -566,6 +570,7 @@ 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;
dma_resv_assert_held(bo->base.resv);
@@ -596,8 +601,9 @@ 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);
@@ -936,11 +942,39 @@ 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);
@@ -954,12 +988,25 @@ 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 +1479,18 @@ 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 = {};
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;
+ }
}
/**
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
index 51f70bea41cc..6a04261ce760 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
@@ -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);
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index da8208f43378..f02f7cf9ae90 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -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
