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drm/msm: Add _NO_SHARE flag

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Buffers that are not shared between contexts can share a single resv
object.  This way drm_gpuvm will not track them as external objects, and
submit-time validating overhead will be O(1) for all N non-shared BOs,
instead of O(n).

Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Tested-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Antonino Maniscalco <antomani103@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/661497/
This commit is contained in:
Rob Clark 2025-06-29 13:13:07 -07:00 committed by Rob Clark
parent 6a4d287a1a
commit b58e12a66e
4 changed files with 51 additions and 0 deletions
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1
drivers/gpu/drm/msm/msm_drv.h
View File

@ -269,6 +269,7 @@ int msm_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map);
void msm_gem_prime_vunmap(struct drm_gem_object *obj, struct iosys_map *map);
struct drm_gem_object *msm_gem_prime_import_sg_table(struct drm_device *dev,
struct dma_buf_attachment *attach, struct sg_table *sg);
struct dma_buf *msm_gem_prime_export(struct drm_gem_object *obj, int flags);
int msm_gem_prime_pin(struct drm_gem_object *obj);
void msm_gem_prime_unpin(struct drm_gem_object *obj);

21
drivers/gpu/drm/msm/msm_gem.c
View File

@ -546,6 +546,9 @@ static int get_and_pin_iova_range_locked(struct drm_gem_object *obj,
msm_gem_assert_locked(obj);
if (to_msm_bo(obj)->flags & MSM_BO_NO_SHARE)
return -EINVAL;
vma = get_vma_locked(obj, vm, range_start, range_end);
if (IS_ERR(vma))
return PTR_ERR(vma);
@ -1076,6 +1079,14 @@ static void msm_gem_free_object(struct drm_gem_object *obj)
put_pages(obj);
}
if (msm_obj->flags & MSM_BO_NO_SHARE) {
struct drm_gem_object *r_obj =
container_of(obj->resv, struct drm_gem_object, _resv);
/* Drop reference we hold to shared resv obj: */
drm_gem_object_put(r_obj);
}
drm_gem_object_release(obj);
kfree(msm_obj->metadata);
@ -1108,6 +1119,15 @@ int msm_gem_new_handle(struct drm_device *dev, struct drm_file *file,
if (name)
msm_gem_object_set_name(obj, "%s", name);
if (flags & MSM_BO_NO_SHARE) {
struct msm_context *ctx = file->driver_priv;
struct drm_gem_object *r_obj = drm_gpuvm_resv_obj(ctx->vm);
drm_gem_object_get(r_obj);
obj->resv = r_obj->resv;
}
ret = drm_gem_handle_create(file, obj, handle);
/* drop reference from allocate - handle holds it now */
@ -1140,6 +1160,7 @@ static const struct drm_gem_object_funcs msm_gem_object_funcs = {
.free = msm_gem_free_object,
.open = msm_gem_open,
.close = msm_gem_close,
.export = msm_gem_prime_export,
.pin = msm_gem_prime_pin,
.unpin = msm_gem_prime_unpin,
.get_sg_table = msm_gem_prime_get_sg_table,

15
drivers/gpu/drm/msm/msm_gem_prime.c
View File

@ -16,6 +16,9 @@ struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj)
struct msm_gem_object *msm_obj = to_msm_bo(obj);
int npages = obj->size >> PAGE_SHIFT;
if (msm_obj->flags & MSM_BO_NO_SHARE)
return ERR_PTR(-EINVAL);
if (WARN_ON(!msm_obj->pages)) /* should have already pinned! */
return ERR_PTR(-ENOMEM);
@ -45,6 +48,15 @@ struct drm_gem_object *msm_gem_prime_import_sg_table(struct drm_device *dev,
return msm_gem_import(dev, attach->dmabuf, sg);
}
struct dma_buf *msm_gem_prime_export(struct drm_gem_object *obj, int flags)
{
if (to_msm_bo(obj)->flags & MSM_BO_NO_SHARE)
return ERR_PTR(-EPERM);
return drm_gem_prime_export(obj, flags);
}
int msm_gem_prime_pin(struct drm_gem_object *obj)
{
struct page **pages;
@ -53,6 +65,9 @@ int msm_gem_prime_pin(struct drm_gem_object *obj)
if (drm_gem_is_imported(obj))
return 0;
if (to_msm_bo(obj)->flags & MSM_BO_NO_SHARE)
return -EINVAL;
pages = msm_gem_pin_pages_locked(obj);
if (IS_ERR(pages))
ret = PTR_ERR(pages);

14
include/uapi/drm/msm_drm.h
View File

@ -140,6 +140,19 @@ struct drm_msm_param {
#define MSM_BO_SCANOUT 0x00000001 /* scanout capable */
#define MSM_BO_GPU_READONLY 0x00000002
/* Private buffers do not need to be explicitly listed in the SUBMIT
* ioctl, unless referenced by a drm_msm_gem_submit_cmd. Private
* buffers may NOT be imported/exported or used for scanout (or any
* other situation where buffers can be indefinitely pinned, but
* cases other than scanout are all kernel owned BOs which are not
* visible to userspace).
*
* In exchange for those constraints, all private BOs associated with
* a single context (drm_file) share a single dma_resv, and if there
* has been no eviction since the last submit, there are no per-BO
* bookeeping to do, significantly cutting the SUBMIT overhead.
*/
#define MSM_BO_NO_SHARE 0x00000004
#define MSM_BO_CACHE_MASK 0x000f0000
/* cache modes */
#define MSM_BO_CACHED 0x00010000
@ -149,6 +162,7 @@ struct drm_msm_param {
#define MSM_BO_FLAGS (MSM_BO_SCANOUT | \
MSM_BO_GPU_READONLY | \
MSM_BO_NO_SHARE | \
MSM_BO_CACHE_MASK)
struct drm_msm_gem_new {