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Message-ID: <20241207161651.410556-19-robdclark@gmail.com>
Date: Sat, 7 Dec 2024 08:15:18 -0800
From: Rob Clark <robdclark@...il.com>
To: dri-devel@...ts.freedesktop.org
Cc: freedreno@...ts.freedesktop.org,
linux-arm-msm@...r.kernel.org,
Connor Abbott <cwabbott0@...il.com>,
Akhil P Oommen <quic_akhilpo@...cinc.com>,
Rob Clark <robdclark@...omium.org>,
Rob Clark <robdclark@...il.com>,
Abhinav Kumar <quic_abhinavk@...cinc.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Sean Paul <sean@...rly.run>,
Marijn Suijten <marijn.suijten@...ainline.org>,
David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>,
Konrad Dybcio <konradybcio@...nel.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
Sumit Semwal <sumit.semwal@...aro.org>,
Christian König <christian.koenig@....com>,
linux-kernel@...r.kernel.org (open list),
linux-media@...r.kernel.org (open list:DMA BUFFER SHARING FRAMEWORK:Keyword:\bdma_(?:buf|fence|resv)\b),
linaro-mm-sig@...ts.linaro.org (moderated list:DMA BUFFER SHARING FRAMEWORK:Keyword:\bdma_(?:buf|fence|resv)\b)
Subject: [RFC 18/24] drm/msm: Add _NO_SHARE flag
From: Rob Clark <robdclark@...omium.org>
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@...omium.org>
---
drivers/gpu/drm/msm/msm_drv.h | 1 +
drivers/gpu/drm/msm/msm_gem.c | 23 +++++++++++++++++++++++
drivers/gpu/drm/msm/msm_gem_prime.c | 15 +++++++++++++++
include/uapi/drm/msm_drm.h | 14 ++++++++++++++
4 files changed, 53 insertions(+)
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 80582c0c2bf7..4c7ff83a0a20 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -246,6 +246,7 @@ 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);
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 66332481c4c3..c21e1284f289 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -511,6 +511,9 @@ 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);
@@ -1026,6 +1029,16 @@ static void msm_gem_free_object(struct drm_gem_object *obj)
put_iova_vmas(obj);
}
+ if (msm_obj->flags & MSM_BO_NO_SHARE) {
+ struct drm_gem_object *r_obj =
+ container_of(obj->resv, struct drm_gem_object, _resv);
+
+ BUG_ON(obj->resv == &obj->_resv);
+
+ /* Drop reference we hold to shared resv obj: */
+ drm_gem_object_put(r_obj);
+ }
+
drm_gem_object_release(obj);
kfree(msm_obj->metadata);
@@ -1058,6 +1071,15 @@ 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 */
@@ -1090,6 +1112,7 @@ 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,
diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c b/drivers/gpu/drm/msm/msm_gem_prime.c
index ee267490c935..1a6d8099196a 100644
--- a/drivers/gpu/drm/msm/msm_gem_prime.c
+++ b/drivers/gpu/drm/msm/msm_gem_prime.c
@@ -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 (obj->import_attach)
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);
diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
index 39b55c8d7413..a7e48ee1dd95 100644
--- a/include/uapi/drm/msm_drm.h
+++ b/include/uapi/drm/msm_drm.h
@@ -138,6 +138,19 @@ 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
@@ -147,6 +160,7 @@ 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 {
--
2.47.1
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