vGEM buffers are useful for passing data between software clients and
hardware renders. By allowing the user to create and attach fences to
the exported vGEM buffers (on the dma-buf), the user can implement a
deferred renderer and queue hardware operations like flipping and then
signal the buffer readiness (i.e. this allows the user to schedule
operations out-of-order, but have them complete in-order).
This also makes it much easier to write tightly controlled testcases for
dma-buf fencing and signaling between hardware drivers.
v2: Don't pretend the fences exist in an ordered timeline, but allocate
a separate fence-context for each fence so that the fences are
unordered.
v3: Make the debug output more interesting, and show the signaled status.
v4: Automatically signal the fence to prevent userspace from
indefinitely hanging drivers.
Testcase: igt/vgem_basic/dmabuf-fence
Testcase: igt/vgem_slow/nohang
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
Cc: Zach Reizner <zachr@xxxxxxxxxx>
Cc: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Acked-by: Zach Reizner <zachr@xxxxxxxxxx>
---
drivers/gpu/drm/vgem/Makefile | 2 +-
drivers/gpu/drm/vgem/vgem_drv.c | 34 +++++
drivers/gpu/drm/vgem/vgem_drv.h | 16 +++
drivers/gpu/drm/vgem/vgem_fence.c | 283 ++++++++++++++++++++++++++++++++++++++
include/uapi/drm/vgem_drm.h | 62 +++++++++
5 files changed, 396 insertions(+), 1 deletion(-)
create mode 100644 drivers/gpu/drm/vgem/vgem_fence.c
create mode 100644 include/uapi/drm/vgem_drm.h
diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
index 3f4c7b842028..bfcdea1330e6 100644
--- a/drivers/gpu/drm/vgem/Makefile
+++ b/drivers/gpu/drm/vgem/Makefile
@@ -1,4 +1,4 @@
ccflags-y := -Iinclude/drm
-vgem-y := vgem_drv.o
+vgem-y := vgem_drv.o vgem_fence.o
obj-$(CONFIG_DRM_VGEM) += vgem.o
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 29c2aab3c1a7..c15bafb06665 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -83,6 +83,34 @@ static const struct vm_operations_struct vgem_gem_vm_ops = {
.close = drm_gem_vm_close,
};
+static int vgem_open(struct drm_device *dev, struct drm_file *file)
+{
+ struct vgem_file *vfile;
+ int ret;
+
+ vfile = kzalloc(sizeof(*vfile), GFP_KERNEL);
+ if (!vfile)
+ return -ENOMEM;
+
+ file->driver_priv = vfile;
+
+ ret = vgem_fence_open(vfile);
+ if (ret) {
+ kfree(vfile);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
+{
+ struct vgem_file *vfile = file->driver_priv;
+
+ vgem_fence_close(vfile);
+ kfree(vfile);
+}
+
/* ioctls */
static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
@@ -164,6 +192,8 @@ unref:
}
static struct drm_ioctl_desc vgem_ioctls[] = {
+ DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
+ DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
};
static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
@@ -271,9 +301,12 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
static struct drm_driver vgem_driver = {
.driver_features = DRIVER_GEM | DRIVER_PRIME,
+ .open = vgem_open,
+ .preclose = vgem_preclose,
.gem_free_object_unlocked = vgem_gem_free_object,
.gem_vm_ops = &vgem_gem_vm_ops,
.ioctls = vgem_ioctls,
+ .num_ioctls = ARRAY_SIZE(vgem_ioctls),
.fops = &vgem_driver_fops,
.dumb_create = vgem_gem_dumb_create,
@@ -328,5 +361,6 @@ module_init(vgem_init);
module_exit(vgem_exit);
MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL and additional rights");
diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
index 988cbaae7588..1f8798ad329c 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.h
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -32,9 +32,25 @@
#include <drm/drmP.h>
#include <drm/drm_gem.h>
+#include <uapi/drm/vgem_drm.h>
+
+struct vgem_file {
+ struct idr fence_idr;
+ struct mutex fence_mutex;
+};
+
#define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
struct drm_vgem_gem_object {
struct drm_gem_object base;
};
+int vgem_fence_open(struct vgem_file *file);
+int vgem_fence_attach_ioctl(struct drm_device *dev,
+ void *data,
+ struct drm_file *file);
+int vgem_fence_signal_ioctl(struct drm_device *dev,
+ void *data,
+ struct drm_file *file);
+void vgem_fence_close(struct vgem_file *file);
+
#endif
diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
new file mode 100644
index 000000000000..e77b52208699
--- /dev/null
+++ b/drivers/gpu/drm/vgem/vgem_fence.c
@@ -0,0 +1,283 @@
+/*
+ * Copyright 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software")
+ * to deal in the software without restriction, including without limitation
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, and/or sell copies of the Software, and to permit persons to whom
+ * them Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTIBILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/reservation.h>
+
+#include "vgem_drv.h"
+
+#define VGEM_FENCE_TIMEOUT (10*HZ)
+
+struct vgem_fence {
+ struct fence base;
+ struct spinlock lock;
+ struct timer_list timer;
+};
+
+static const char *vgem_fence_get_driver_name(struct fence *fence)
+{
+ return "vgem";
+}
+
+static const char *vgem_fence_get_timeline_name(struct fence *fence)
+{
+ return "unbound";
+}
+
+static bool vgem_fence_signaled(struct fence *fence)
+{
+ return false;
+}
+
+static bool vgem_fence_enable_signaling(struct fence *fence)
+{
+ return true;
+}
+
+static void vgem_fence_release(struct fence *base)
+{
+ struct vgem_fence *fence = container_of(base, typeof(*fence), base);
+
+ del_timer_sync(&fence->timer);
+ fence_free(&fence->base);
+}
+
+static void vgem_fence_value_str(struct fence *fence, char *str, int size)
+{
+ snprintf(str, size, "%u", fence->seqno);
+}
+
+static void vgem_fence_timeline_value_str(struct fence *fence, char *str,
+ int size)
+{
+ snprintf(str, size, "%u", fence_is_signaled(fence) ? fence->seqno : 0);
+}
+
+const struct fence_ops vgem_fence_ops = {
+ .get_driver_name = vgem_fence_get_driver_name,
+ .get_timeline_name = vgem_fence_get_timeline_name,
+ .enable_signaling = vgem_fence_enable_signaling,
+ .signaled = vgem_fence_signaled,
+ .wait = fence_default_wait,
+ .release = vgem_fence_release,
+
+ .fence_value_str = vgem_fence_value_str,
+ .timeline_value_str = vgem_fence_timeline_value_str,
+};
+
+static void vgem_fence_timeout(unsigned long data)
+{
+ struct vgem_fence *fence = (struct vgem_fence *)data;
+
+ fence_signal(&fence->base);
+}
+
+static struct fence *vgem_fence_create(struct vgem_file *vfile,
+ unsigned int flags)
+{
+ struct vgem_fence *fence;
+
+ fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+ if (!fence)
+ return NULL;
+
+ spin_lock_init(&fence->lock);
+ fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
+ fence_context_alloc(1), 1);
+
+ setup_timer(&fence->timer, vgem_fence_timeout, (unsigned long)fence);
+
+ /* We force the fence to expire within 10s to prevent driver hangs */
+ mod_timer(&fence->timer, VGEM_FENCE_TIMEOUT);
+
+ return &fence->base;
+}
+
+static int attach_dmabuf(struct drm_device *dev,
+ struct drm_gem_object *obj)
+{
+ struct dma_buf *dmabuf;
+
+ if (obj->dma_buf)
+ return 0;
+
+ dmabuf = dev->driver->gem_prime_export(dev, obj, 0);
+ if (IS_ERR(dmabuf))
+ return PTR_ERR(dmabuf);
+
+ obj->dma_buf = dmabuf;
+ drm_gem_object_reference(obj);
+ return 0;
+}
+
+/*
+ * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH):
+ *
+ * Create and attach a fence to the vGEM handle. This fence is then exposed
+ * via the dma-buf reservation object and visible to consumers of the exported
+ * dma-buf. If the flags contain VGEM_FENCE_WRITE, the fence indicates the
+ * vGEM buffer is being written to by the client and is exposed as an exclusive
+ * fence, otherwise the fence indicates the client is current reading from the
+ * buffer and all future writes should wait for the client to signal its
+ * completion. Note that if a conflicting fence is already on the dma-buf (i.e.
+ * an exclusive fence when adding a read, or any fence when adding a write),
+ * -EBUSY is reported. Serialisation between operations should be handled
+ * by waiting upon the dma-buf.
+ *
+ * This returns the handle for the new fence that must be signaled within 10
+ * seconds (or otherwise it will automatically expire). See
+ * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL).
+ *
+ * If the vGEM handle does not exist, vgem_fence_attach_ioctl returns -ENOENT.
+ */
+int vgem_fence_attach_ioctl(struct drm_device *dev,
+ void *data,
+ struct drm_file *file)
+{
+ struct drm_vgem_fence_attach *arg = data;
+ struct vgem_file *vfile = file->driver_priv;
+ struct reservation_object *resv;
+ struct drm_gem_object *obj;
+ struct fence *fence;
+ int ret;
+
+ if (arg->flags & ~VGEM_FENCE_WRITE)
+ return -EINVAL;
+
+ if (arg->pad)
+ return -EINVAL;
+
+ obj = drm_gem_object_lookup(file, arg->handle);
+ if (!obj)
+ return -ENOENT;
+
+ ret = attach_dmabuf(dev, obj);
+ if (ret)
+ goto err;
+
+ fence = vgem_fence_create(vfile, arg->flags);
+ if (!fence) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ /* Check for a conflicting fence */
+ resv = obj->dma_buf->resv;
+ if (!reservation_object_test_signaled_rcu(resv,
+ arg->flags & VGEM_FENCE_WRITE)) {
+ ret = -EBUSY;
+ goto err_fence;
+ }
+
+ /* Expose the fence via the dma-buf */
+ ret = 0;
+ mutex_lock(&resv->lock.base);
+ if (arg->flags & VGEM_FENCE_WRITE)
+ reservation_object_add_excl_fence(resv, fence);
+ else if ((ret = reservation_object_reserve_shared(resv)) == 0)
+ reservation_object_add_shared_fence(resv, fence);
+ mutex_unlock(&resv->lock.base);
+
+ /* Record the fence in our idr for later signaling */
+ if (ret == 0) {
+ mutex_lock(&vfile->fence_mutex);
+ ret = idr_alloc(&vfile->fence_idr, fence, 1, 0, GFP_KERNEL);
+ mutex_unlock(&vfile->fence_mutex);
+ if (ret > 0) {
+ arg->out_fence = ret;
+ ret = 0;
+ }
+ }
+err_fence:
+ if (ret) {
+ fence_signal(fence);
+ fence_put(fence);
+ }
+err:
+ drm_gem_object_unreference_unlocked(obj);
+ return ret;
+}
+
+/*
+ * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL):
+ *
+ * Signal and consume a fence ealier attached to a vGEM handle using
+ * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH).
+ *
+ * All fences must be signaled within 10s of attachment or otherwise they
+ * will automatically expire (and a vgem_fence_signal_ioctl returns -ETIMEDOUT).
+ *
+ * Signaling a fence indicates to all consumers of the dma-buf that the
+ * client has completed the operation associated with the fence, and that the
+ * buffer is then ready for consumption.
+ *
+ * If the fence does not exist (or has already been signaled by the client),
+ * vgem_fence_signal_ioctl returns -ENOENT.
+ */
+int vgem_fence_signal_ioctl(struct drm_device *dev,
+ void *data,
+ struct drm_file *file)
+{
+ struct vgem_file *vfile = file->driver_priv;
+ struct drm_vgem_fence_signal *arg = data;
+ struct fence *fence;
+ int ret;
+
+ if (arg->flags)
+ return -EINVAL;
+
+ mutex_lock(&vfile->fence_mutex);
+ fence = idr_replace(&vfile->fence_idr, NULL, arg->fence);
+ mutex_unlock(&vfile->fence_mutex);
+ if (!fence)
+ return -ENOENT;
+ if (IS_ERR(fence))
+ return PTR_ERR(fence);
+
+ if (fence_is_signaled(fence))
+ ret = -ETIMEDOUT;
+
+ fence_signal(fence);
+ fence_put(fence);
+ return ret;
+}
+
+int vgem_fence_open(struct vgem_file *vfile)
+{
+ mutex_init(&vfile->fence_mutex);
+ idr_init(&vfile->fence_idr);
+
+ return 0;
+}
+
+static int __vgem_fence_idr_fini(int id, void *p, void *data)
+{
+ fence_signal(p);
+ fence_put(p);
+ return 0;
+}
+
+void vgem_fence_close(struct vgem_file *vfile)
+{
+ idr_for_each(&vfile->fence_idr, __vgem_fence_idr_fini, vfile);
+ idr_destroy(&vfile->fence_idr);
+}
diff --git a/include/uapi/drm/vgem_drm.h b/include/uapi/drm/vgem_drm.h
new file mode 100644
index 000000000000..bf66f5db6da8
--- /dev/null
+++ b/include/uapi/drm/vgem_drm.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2016 Intel Corporation
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#ifndef _UAPI_VGEM_DRM_H_
+#define _UAPI_VGEM_DRM_H_
+
+#include "drm.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/* Please note that modifications to all structs defined here are
+ * subject to backwards-compatibility constraints.
+ */
+#define DRM_VGEM_FENCE_ATTACH 0x1
+#define DRM_VGEM_FENCE_SIGNAL 0x2
+
+#define DRM_IOCTL_VGEM_FENCE_ATTACH DRM_IOWR( DRM_COMMAND_BASE + DRM_VGEM_FENCE_ATTACH, struct drm_vgem_fence_attach)
+#define DRM_IOCTL_VGEM_FENCE_SIGNAL DRM_IOW( DRM_COMMAND_BASE + DRM_VGEM_FENCE_SIGNAL, struct drm_vgem_fence_signal)
+
+struct drm_vgem_fence_attach {
+ __u32 handle;
+ __u32 flags;
+#define VGEM_FENCE_WRITE 0x1
+ __u32 out_fence;
+ __u32 pad;
+};
+
+struct drm_vgem_fence_signal {
+ __u32 fence;
+ __u32 flags;
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* _UAPI_VGEM_DRM_H_ */
--
2.8.1
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