With the conversion to drm_gpuvm, we lost the lazy VMA cleanup, which
means that fb cleanup/unpin when pageflipping to new scanout buffers
immediately unmaps the scanout buffer. This is costly (with tlbinv,
it can be 4-6ms for a 1080p scanout buffer, and more for higher
resolutions)!
To avoid this, introduce a vma_ref, which is incremented for scanout,
and whenever userspace has a GEM handle or dma-buf fd. When unpinning
if the vm is the kms->vm we defer tearing down the VMA until the
vma_ref drops to zero. If the buffer is still part of a flip-chain
then userspace will be holding some sort of reference to the BO, either
via a GEM handle and/or dma-buf fd. So this avoids unmapping the VMA
when there is a strong possibility that it will be needed again.
Signed-off-by: Rob Clark <robin.cl...@oss.qualcomm.com>
---
drivers/gpu/drm/msm/msm_gem.c | 77 +++++++++++++++++++---------
drivers/gpu/drm/msm/msm_gem.h | 29 +++++++++++
drivers/gpu/drm/msm/msm_gem_prime.c | 35 ++++++++++++-
drivers/gpu/drm/msm/msm_gem_submit.c | 8 +++
4 files changed, 124 insertions(+), 25 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index b882647144bb..55a409ac72f5 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -19,11 +19,11 @@
#include "msm_drv.h"
#include "msm_gem.h"
#include "msm_gpu.h"
+#include "msm_kms.h"
static int pgprot = 0;
module_param(pgprot, int, 0600);
-
static void update_device_mem(struct msm_drm_private *priv, ssize_t size)
{
uint64_t total_mem = atomic64_add_return(size, &priv->total_mem);
@@ -43,6 +43,7 @@ static void update_ctx_mem(struct drm_file *file, ssize_t
size)
static int msm_gem_open(struct drm_gem_object *obj, struct drm_file *file)
{
+ msm_gem_vma_get(obj);
update_ctx_mem(file, obj->size);
return 0;
}
@@ -50,33 +51,13 @@ static int msm_gem_open(struct drm_gem_object *obj, struct
drm_file *file)
static void put_iova_spaces(struct drm_gem_object *obj, struct drm_gpuvm *vm,
bool close, const char *reason);
-static void detach_vm(struct drm_gem_object *obj, struct drm_gpuvm *vm)
-{
- msm_gem_assert_locked(obj);
- drm_gpuvm_resv_assert_held(vm);
-
- struct drm_gpuvm_bo *vm_bo = drm_gpuvm_bo_find(vm, obj);
- if (vm_bo) {
- struct drm_gpuva *vma;
-
- drm_gpuvm_bo_for_each_va (vma, vm_bo) {
- if (vma->vm != vm)
- continue;
- msm_gem_vma_unmap(vma, "detach");
- msm_gem_vma_close(vma);
- break;
- }
-
- drm_gpuvm_bo_put(vm_bo);
- }
-}
-
static void msm_gem_close(struct drm_gem_object *obj, struct drm_file *file)
{
struct msm_context *ctx = file->driver_priv;
struct drm_exec exec;
update_ctx_mem(file, -obj->size);
+ msm_gem_vma_put(obj);
/*
* If VM isn't created yet, nothing to cleanup. And in fact calling
@@ -103,10 +84,47 @@ static void msm_gem_close(struct drm_gem_object *obj,
struct drm_file *file)
msm_gem_lock_vm_and_obj(&exec, obj, ctx->vm);
put_iova_spaces(obj, ctx->vm, true, "close");
- detach_vm(obj, ctx->vm);
drm_exec_fini(&exec); /* drop locks */
}
+/*
+ * Get/put for kms->vm VMA
+ */
+
+void msm_gem_vma_get(struct drm_gem_object *obj)
+{
+ atomic_inc(&to_msm_bo(obj)->vma_ref);
+}
+
+void msm_gem_vma_put(struct drm_gem_object *obj)
+{
+ struct msm_drm_private *priv = obj->dev->dev_private;
+ struct drm_exec exec;
+
+ if (atomic_dec_return(&to_msm_bo(obj)->vma_ref))
+ return;
+
+ if (!priv->kms)
+ return;
+
+ msm_gem_lock_vm_and_obj(&exec, obj, priv->kms->vm);
+ put_iova_spaces(obj, priv->kms->vm, true, "vma_put");
+ drm_exec_fini(&exec); /* drop locks */
+}
+
+static void msm_gem_vma_put_locked(struct drm_gem_object *obj)
+{
+ struct msm_drm_private *priv = obj->dev->dev_private;
+
+ if (atomic_dec_return(&to_msm_bo(obj)->vma_ref))
+ return;
+
+ if (!priv->kms)
+ return;
+
+ put_iova_spaces(obj, priv->kms->vm, true, "vma_put");
+}
+
/*
* Cache sync.. this is a bit over-complicated, to fit dma-mapping
* API. Really GPU cache is out of scope here (handled on cmdstream)
@@ -281,6 +299,7 @@ void msm_gem_pin_obj_locked(struct drm_gem_object *obj)
msm_gem_assert_locked(obj);
to_msm_bo(obj)->pin_count++;
+ msm_gem_vma_get(obj);
drm_gem_lru_move_tail_locked(&priv->lru.pinned, obj);
}
@@ -518,6 +537,8 @@ void msm_gem_unpin_locked(struct drm_gem_object *obj)
msm_gem_assert_locked(obj);
+ msm_gem_vma_put_locked(obj);
+
mutex_lock(&priv->lru.lock);
msm_obj->pin_count--;
GEM_WARN_ON(msm_obj->pin_count < 0);
@@ -664,6 +685,13 @@ int msm_gem_set_iova(struct drm_gem_object *obj,
return ret;
}
+static bool is_kms_vm(struct drm_gpuvm *vm)
+{
+ struct msm_drm_private *priv = vm->drm->dev_private;
+
+ return priv->kms && (priv->kms->vm == vm);
+}
+
/*
* Unpin a iova by updating the reference counts. The memory isn't actually
* purged until something else (shrinker, mm_notifier, destroy, etc) decides
@@ -679,7 +707,8 @@ void msm_gem_unpin_iova(struct drm_gem_object *obj, struct
drm_gpuvm *vm)
if (vma) {
msm_gem_unpin_locked(obj);
}
- detach_vm(obj, vm);
+ if (!is_kms_vm(vm))
+ put_iova_spaces(obj, vm, true, "close");
drm_exec_fini(&exec); /* drop locks */
}
diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index 9671c4299cf8..fafb221e173b 100644
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -211,9 +211,38 @@ struct msm_gem_object {
* Protected by LRU lock.
*/
int pin_count;
+
+ /**
+ * @vma_ref: Reference count of VMA users.
+ *
+ * With the vm_bo/vma holding a reference to the GEM object, we'd
+ * otherwise have to actively tear down a VMA when, for example,
+ * a buffer is unpinned for scanout, vs. the pre-drm_gpuvm approach
+ * where a VMA did not hold a reference to the BO, but instead was
+ * implicitly torn down when the BO was freed.
+ *
+ * To regain the lazy VMA teardown, we use the @vma_ref. It is
+ * incremented for any of the following:
+ *
+ * 1) the BO is pinned for scanout/etc
+ * 2) the BO is exported as a dma_buf
+ * 3) the BO has open userspace handle
+ *
+ * All of those conditions will hold an reference to the BO,
+ * preventing it from being freed. So lazily keeping around the
+ * VMA will not prevent the BO from being freed. (Or rather, the
+ * reference loop is harmless in this case.)
+ *
+ * When the @vma_ref drops to zero, then kms->vm VMA will be
+ * torn down.
+ */
+ atomic_t vma_ref;
};
#define to_msm_bo(x) container_of(x, struct msm_gem_object, base)
+void msm_gem_vma_get(struct drm_gem_object *obj);
+void msm_gem_vma_put(struct drm_gem_object *obj);
+
uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj);
int msm_gem_prot(struct drm_gem_object *obj);
int msm_gem_pin_vma_locked(struct drm_gem_object *obj, struct drm_gpuva *vma);
diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c
b/drivers/gpu/drm/msm/msm_gem_prime.c
index 1a6d8099196a..43f264d3cfa9 100644
--- a/drivers/gpu/drm/msm/msm_gem_prime.c
+++ b/drivers/gpu/drm/msm/msm_gem_prime.c
@@ -6,6 +6,7 @@
#include <linux/dma-buf.h>
+#include <drm/drm_drv.h>
#include <drm/drm_prime.h>
#include "msm_drv.h"
@@ -48,13 +49,45 @@ struct drm_gem_object *msm_gem_prime_import_sg_table(struct
drm_device *dev,
return msm_gem_import(dev, attach->dmabuf, sg);
}
+static void msm_gem_dmabuf_release(struct dma_buf *dma_buf)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+
+ msm_gem_vma_put(obj);
+ drm_gem_dmabuf_release(dma_buf);
+}
+
+static const struct dma_buf_ops msm_gem_prime_dmabuf_ops = {
+ .cache_sgt_mapping = true,
+ .attach = drm_gem_map_attach,
+ .detach = drm_gem_map_detach,
+ .map_dma_buf = drm_gem_map_dma_buf,
+ .unmap_dma_buf = drm_gem_unmap_dma_buf,
+ .release = msm_gem_dmabuf_release,
+ .mmap = drm_gem_dmabuf_mmap,
+ .vmap = drm_gem_dmabuf_vmap,
+ .vunmap = drm_gem_dmabuf_vunmap,
+};
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);
+ msm_gem_vma_get(obj);
+
+ struct drm_device *dev = obj->dev;
+ struct dma_buf_export_info exp_info = {
+ .exp_name = KBUILD_MODNAME, /* white lie for debug */
+ .owner = dev->driver->fops->owner,
+ .ops = &msm_gem_prime_dmabuf_ops,
+ .size = obj->size,
+ .flags = flags,
+ .priv = obj,
+ .resv = obj->resv,
+ };
+
+ return drm_gem_dmabuf_export(dev, &exp_info);
}
int msm_gem_prime_pin(struct drm_gem_object *obj)
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c
b/drivers/gpu/drm/msm/msm_gem_submit.c
index 8a0f5b5eda30..bf9010da7e58 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -527,6 +527,14 @@ void msm_submit_retire(struct msm_gem_submit *submit)
struct drm_gem_object *obj = submit->bos[i].obj;
struct drm_gpuvm_bo *vm_bo = submit->bos[i].vm_bo;
+ /*
+ * msm_gem_unpin_active() doesn't drop the vma ref, because
+ * requires grabbing locks which we cannot grab in the fence
+ * signaling path. So we have to do that here
+ */
+ if (submit->bos_pinned)
+ msm_gem_vma_put(obj);
+
drm_gem_object_put(obj);
drm_gpuvm_bo_put(vm_bo);
}
--
2.49.0
