[PATCH v5 09/21] gpu: host1x: DMA fences and userspace fence creation

Mikko Perttunen
2021-01-11T13:02:16Z

Add an implementation of dma_fences based on syncpoints. Syncpoint
interrupts are used to signal fences. Additionally, after
software signaling has been enabled, a 30 second timeout is started.
If the syncpoint threshold is not reached within this period,
the fence is signalled with an -ETIMEDOUT error code. This is to
allow fences that would never reach their syncpoint threshold to
be cleaned up.

Additionally, add a new /dev/host1x IOCTL for creating sync_file
file descriptors backed by syncpoint fences.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
v5:
* Update for change in put_ref prototype.
v4:
* Fix _signal prototype and include it to avoid warning
* Remove use of unused local in error path
v3:
* Move declaration of host1x_fence_extract to public header
---
drivers/gpu/host1x/Makefile | 1 +
drivers/gpu/host1x/fence.c | 208 ++++++++++++++++++++++++++++++++++++
drivers/gpu/host1x/fence.h | 13 +++
drivers/gpu/host1x/intr.c | 9 ++
drivers/gpu/host1x/intr.h | 2 +
drivers/gpu/host1x/uapi.c | 103 ++++++++++++++++++
include/linux/host1x.h | 4 +
7 files changed, 340 insertions(+)
create mode 100644 drivers/gpu/host1x/fence.c
create mode 100644 drivers/gpu/host1x/fence.h

diff --git a/drivers/gpu/host1x/Makefile b/drivers/gpu/host1x/Makefile
index 882f928d75e1..a48af2cefae1 100644
--- a/drivers/gpu/host1x/Makefile
+++ b/drivers/gpu/host1x/Makefile
@@ -10,6 +10,7 @@ host1x-y = \
debug.o \
mipi.o \
uapi.o \
+ fence.o \
hw/host1x01.o \
hw/host1x02.o \
hw/host1x04.o \
diff --git a/drivers/gpu/host1x/fence.c b/drivers/gpu/host1x/fence.c
new file mode 100644
index 000000000000..e96ad93ff656
--- /dev/null
+++ b/drivers/gpu/host1x/fence.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Syncpoint dma_fence implementation
+ *
+ * Copyright (c) 2020, NVIDIA Corporation.
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/sync_file.h>
+
+#include "fence.h"
+#include "intr.h"
+#include "syncpt.h"
+
+DEFINE_SPINLOCK(lock);
+
+struct host1x_syncpt_fence {
+ struct dma_fence base;
+
+ atomic_t signaling;
+
+ struct host1x_syncpt *sp;
+ u32 threshold;
+
+ struct host1x_waitlist *waiter;
+ void *waiter_ref;
+
+ struct delayed_work timeout_work;
+};
+
+static const char *syncpt_fence_get_driver_name(struct dma_fence *f)
+{
+ return "host1x";
+}
+
+static const char *syncpt_fence_get_timeline_name(struct dma_fence *f)
+{
+ return "syncpoint";
+}
+
+static bool syncpt_fence_enable_signaling(struct dma_fence *f)
+{
+ struct host1x_syncpt_fence *sf =
+ container_of(f, struct host1x_syncpt_fence, base);
+ int err;
+
+ if (host1x_syncpt_is_expired(sf->sp, sf->threshold))
+ return false;
+
+ dma_fence_get(f);
+
+ /*
+ * The dma_fence framework requires the fence driver to keep a
+ * reference to any fences for which 'enable_signaling' has been
+ * called (and that have not been signalled).
+ *
+ * We provide a userspace API to create arbitrary syncpoint fences,
+ * so we cannot normally guarantee that all fences get signalled.
+ * As such, setup a timeout, so that long-lasting fences will get
+ * reaped eventually.
+ */
+ schedule_delayed_work(&sf->timeout_work, msecs_to_jiffies(30000));
+
+ err = host1x_intr_add_action(sf->sp->host, sf->sp, sf->threshold,
+ HOST1X_INTR_ACTION_SIGNAL_FENCE, f,
+ sf->waiter, &sf->waiter_ref);
+ if (err) {
+ cancel_delayed_work_sync(&sf->timeout_work);
+ dma_fence_put(f);
+ return false;
+ }
+
+ /* intr framework takes ownership of waiter */
+ sf->waiter = NULL;
+
+ /*
+ * The fence may get signalled at any time after the above call,
+ * so we need to initialize all state used by signalling
+ * before it.
+ */
+
+ return true;
+}
+
+static void syncpt_fence_release(struct dma_fence *f)
+{
+ struct host1x_syncpt_fence *sf =
+ container_of(f, struct host1x_syncpt_fence, base);
+
+ if (sf->waiter)
+ kfree(sf->waiter);
+
+ dma_fence_free(f);
+}
+
+const struct dma_fence_ops syncpt_fence_ops = {
+ .get_driver_name = syncpt_fence_get_driver_name,
+ .get_timeline_name = syncpt_fence_get_timeline_name,
+ .enable_signaling = syncpt_fence_enable_signaling,
+ .release = syncpt_fence_release,
+};
+
+void host1x_fence_signal(struct host1x_syncpt_fence *f)
+{
+ if (atomic_xchg(&f->signaling, 1))
+ return;
+
+ /*
+ * Cancel pending timeout work - if it races, it will
+ * not get 'f->signaling' and return.
+ */
+ cancel_delayed_work_sync(&f->timeout_work);
+
+ host1x_intr_put_ref(f->sp->host, f->sp->id, f->waiter_ref, false);
+
+ dma_fence_signal(&f->base);
+ dma_fence_put(&f->base);
+}
+
+static void do_fence_timeout(struct work_struct *work)
+{
+ struct delayed_work *dwork = (struct delayed_work *)work;
+ struct host1x_syncpt_fence *f =
+ container_of(dwork, struct host1x_syncpt_fence, timeout_work);
+
+ if (atomic_xchg(&f->signaling, 1))
+ return;
+
+ /*
+ * Cancel pending timeout work - if it races, it will
+ * not get 'f->signaling' and return.
+ */
+ host1x_intr_put_ref(f->sp->host, f->sp->id, f->waiter_ref, true);
+
+ dma_fence_set_error(&f->base, -ETIMEDOUT);
+ dma_fence_signal(&f->base);
+ dma_fence_put(&f->base);
+}
+
+struct dma_fence *host1x_fence_create(struct host1x_syncpt *sp, u32 threshold)
+{
+ struct host1x_syncpt_fence *fence;
+
+ fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+ if (!fence)
+ return ERR_PTR(-ENOMEM);
+
+ fence->waiter = kzalloc(sizeof(*fence->waiter), GFP_KERNEL);
+ if (!fence->waiter)
+ return ERR_PTR(-ENOMEM);
+
+ fence->sp = sp;
+ fence->threshold = threshold;
+
+ dma_fence_init(&fence->base, &syncpt_fence_ops, &lock,
+ dma_fence_context_alloc(1), 0);
+
+ INIT_DELAYED_WORK(&fence->timeout_work, do_fence_timeout);
+
+ return &fence->base;
+}
+EXPORT_SYMBOL(host1x_fence_create);
+
+int host1x_fence_create_fd(struct host1x_syncpt *sp, u32 threshold)
+{
+ struct sync_file *file;
+ struct dma_fence *f;
+ int fd;
+
+ f = host1x_fence_create(sp, threshold);
+ if (IS_ERR(f))
+ return PTR_ERR(f);
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0) {
+ dma_fence_put(f);
+ return fd;
+ }
+
+ file = sync_file_create(f);
+ dma_fence_put(f);
+ if (!file)
+ return -ENOMEM;
+
+ fd_install(fd, file->file);
+
+ return fd;
+}
+EXPORT_SYMBOL(host1x_fence_create_fd);
+
+int host1x_fence_extract(struct dma_fence *fence, u32 *id, u32 *threshold)
+{
+ struct host1x_syncpt_fence *f;
+
+ if (fence->ops != &syncpt_fence_ops)
+ return -EINVAL;
+
+ f = container_of(fence, struct host1x_syncpt_fence, base);
+
+ *id = f->sp->id;
+ *threshold = f->threshold;
+
+ return 0;
+}
+EXPORT_SYMBOL(host1x_fence_extract);
diff --git a/drivers/gpu/host1x/fence.h b/drivers/gpu/host1x/fence.h
new file mode 100644
index 000000000000..70c91de82f14
--- /dev/null
+++ b/drivers/gpu/host1x/fence.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2020, NVIDIA Corporation.
+ */
+
+#ifndef HOST1X_FENCE_H
+#define HOST1X_FENCE_H
+
+struct host1x_syncpt_fence;
+
+void host1x_fence_signal(struct host1x_syncpt_fence *fence);
+
+#endif
diff --git a/drivers/gpu/host1x/intr.c b/drivers/gpu/host1x/intr.c
index 70e1096a4fe9..bcffc4d7879b 100644
--- a/drivers/gpu/host1x/intr.c
+++ b/drivers/gpu/host1x/intr.c
@@ -13,6 +13,7 @@
#include <trace/events/host1x.h>
#include "channel.h"
#include "dev.h"
+#include "fence.h"
#include "intr.h"

/* Wait list management */
@@ -121,12 +122,20 @@ static void action_wakeup_interruptible(struct host1x_waitlist *waiter)
wake_up_interruptible(wq);
}

+static void action_signal_fence(struct host1x_waitlist *waiter)
+{
+ struct host1x_syncpt_fence *f = waiter->data;
+
+ host1x_fence_signal(f);
+}
+
typedef void (*action_handler)(struct host1x_waitlist *waiter);

static const action_handler action_handlers[HOST1X_INTR_ACTION_COUNT] = {
action_submit_complete,
action_wakeup,
action_wakeup_interruptible,
+ action_signal_fence,
};

static void run_handlers(struct list_head completed[HOST1X_INTR_ACTION_COUNT])
diff --git a/drivers/gpu/host1x/intr.h b/drivers/gpu/host1x/intr.h
index 6ea55e615e3a..e4c346099273 100644
--- a/drivers/gpu/host1x/intr.h
+++ b/drivers/gpu/host1x/intr.h
@@ -33,6 +33,8 @@ enum host1x_intr_action {
*/
HOST1X_INTR_ACTION_WAKEUP_INTERRUPTIBLE,

+ HOST1X_INTR_ACTION_SIGNAL_FENCE,
+
HOST1X_INTR_ACTION_COUNT
};

diff --git a/drivers/gpu/host1x/uapi.c b/drivers/gpu/host1x/uapi.c
index 27b8761c3f35..e931756a5e16 100644
--- a/drivers/gpu/host1x/uapi.c
+++ b/drivers/gpu/host1x/uapi.c
@@ -11,8 +11,10 @@
#include <linux/fs.h>
#include <linux/host1x.h>
#include <linux/nospec.h>
+#include <linux/sync_file.h>

#include "dev.h"
+#include "fence.h"
#include "syncpt.h"
#include "uapi.h"

@@ -195,6 +197,99 @@ static int dev_file_ioctl_alloc_syncpoint(struct host1x *host1x,
return err;
}

+static int dev_file_ioctl_create_fence(struct host1x *host1x, void __user *data)
+{
+ struct host1x_create_fence args;
+ unsigned long copy_err;
+ int fd;
+
+ copy_err = copy_from_user(&args, data, sizeof(args));
+ if (copy_err)
+ return -EFAULT;
+
+ if (args.reserved[0])
+ return -EINVAL;
+
+ if (args.id >= host1x_syncpt_nb_pts(host1x))
+ return -EINVAL;
+
+ args.id = array_index_nospec(args.id, host1x_syncpt_nb_pts(host1x));
+
+ fd = host1x_fence_create_fd(&host1x->syncpt[args.id], args.threshold);
+ if (fd < 0)
+ return fd;
+
+ args.fence_fd = fd;
+
+ copy_err = copy_to_user(data, &args, sizeof(args));
+ if (copy_err)
+ return -EFAULT;
+
+ return 0;
+}
+
+static int dev_file_ioctl_fence_extract(struct host1x *host1x, void __user *data)
+{
+ struct host1x_fence_extract_fence __user *fences_user_ptr;
+ struct dma_fence *fence, **fences;
+ struct host1x_fence_extract args;
+ struct dma_fence_array *array;
+ unsigned int num_fences, i;
+ unsigned long copy_err;
+ int err;
+
+ copy_err = copy_from_user(&args, data, sizeof(args));
+ if (copy_err)
+ return -EFAULT;
+
+ fences_user_ptr = u64_to_user_ptr(args.fences_ptr);
+
+ if (args.reserved[0] || args.reserved[1])
+ return -EINVAL;
+
+ fence = sync_file_get_fence(args.fence_fd);
+ if (!fence)
+ return -EINVAL;
+
+ array = to_dma_fence_array(fence);
+ if (array) {
+ fences = array->fences;
+ num_fences = array->num_fences;
+ } else {
+ fences = &fence;
+ num_fences = 1;
+ }
+
+ for (i = 0; i < min(num_fences, args.num_fences); i++) {
+ struct host1x_fence_extract_fence f;
+
+ err = host1x_fence_extract(fences[i], &f.id, &f.threshold);
+ if (err)
+ goto put_fence;
+
+ copy_err = copy_to_user(fences_user_ptr + i, &f, sizeof(f));
+ if (copy_err) {
+ err = -EFAULT;
+ goto put_fence;
+ }
+ }
+
+ args.num_fences = i+1;
+
+ copy_err = copy_to_user(data, &args, sizeof(args));
+ if (copy_err) {
+ err = -EFAULT;
+ goto put_fence;
+ }
+
+ return 0;
+
+put_fence:
+ dma_fence_put(fence);
+
+ return err;
+}
+
static long dev_file_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
@@ -210,6 +305,14 @@ static long dev_file_ioctl(struct file *file, unsigned int cmd,
err = dev_file_ioctl_alloc_syncpoint(file->private_data, data);
break;

+ case HOST1X_IOCTL_CREATE_FENCE:
+ err = dev_file_ioctl_create_fence(file->private_data, data);
+ break;
+
+ case HOST1X_IOCTL_FENCE_EXTRACT:
+ err = dev_file_ioctl_fence_extract(file->private_data, data);
+ break;
+
default:
err = -ENOTTY;
}
diff --git a/include/linux/host1x.h b/include/linux/host1x.h
index b3178ae51cae..080f9d3d29eb 100644
--- a/include/linux/host1x.h
+++ b/include/linux/host1x.h
@@ -165,6 +165,10 @@ u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base);

struct host1x_syncpt *host1x_syncpt_fd_get(int fd);

+struct dma_fence *host1x_fence_create(struct host1x_syncpt *sp, u32 threshold);
+int host1x_fence_create_fd(struct host1x_syncpt *sp, u32 threshold);
+int host1x_fence_extract(struct dma_fence *fence, u32 *id, u32 *threshold);
+
/*
* host1x channel
*/
--
2.30.0