Quelle  vmwgfx_fence.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0 OR MIT
/**************************************************************************
 *
 * Copyright (c) 2009-2025 Broadcom. All Rights Reserved. The term
 * “Broadcom” refers to Broadcom Inc. and/or its subsidiaries.
 *
 **************************************************************************/

#include "vmwgfx_drv.h"

#define VMW_FENCE_WRAP (1 << 31)

struct vmw_fence_manager {
 struct vmw_private *dev_priv;
 spinlock_t lock;
 struct list_head fence_list;
 bool fifo_down;
 u64 ctx;
};

struct vmw_user_fence {
 struct ttm_base_object base;
 struct vmw_fence_obj fence;
};

/**
 * struct vmw_event_fence_action - fence callback that delivers a DRM event.
 *
 * @base:  For use with dma_fence_add_callback(...)
 * @event: A pointer to the pending event.
 * @dev: Pointer to a struct drm_device so we can access the event stuff.
 * @tv_sec: If non-null, the variable pointed to will be assigned
 * current time tv_sec val when the fence signals.
 * @tv_usec: Must be set if @tv_sec is set, and the variable pointed to will
 * be assigned the current time tv_usec val when the fence signals.
 */
struct vmw_event_fence_action {
 struct dma_fence_cb base;

 struct drm_pending_event *event;
 struct drm_device *dev;

 uint32_t *tv_sec;
 uint32_t *tv_usec;
};

static struct vmw_fence_manager *
fman_from_fence(struct vmw_fence_obj *fence)
{
 return container_of(fence->base.lock, struct vmw_fence_manager, lock);
}

static void vmw_fence_obj_destroy(struct dma_fence *f)
{
 struct vmw_fence_obj *fence =
  container_of(f, struct vmw_fence_obj, base);
 struct vmw_fence_manager *fman = fman_from_fence(fence);

 if (!list_empty(&fence->head)) {
  /* The fence manager still has an implicit reference to this
 * fence via the fence list if head is set. Because the lock is
 * required to be held when the fence manager updates the fence
 * list either the fence will have been removed after we get
 * the lock below or we can safely remove it and the fence
 * manager will never see it. This implies the fence is being
 * deleted without being signaled which is dubious but valid
 * if there are no callbacks. The dma_fence code that calls
 * this hook will warn about deleted unsignaled with callbacks
 * so no need to warn again here.
 */
  spin_lock(&fman->lock);
  list_del_init(&fence->head);
  if (fence->waiter_added)
   vmw_seqno_waiter_remove(fman->dev_priv);
  spin_unlock(&fman->lock);
 }
 fence->destroy(fence);
}

static const char *vmw_fence_get_driver_name(struct dma_fence *f)
{
 return "vmwgfx";
}

static const char *vmw_fence_get_timeline_name(struct dma_fence *f)
{
 return "svga";
}

/* When we toggle signaling for the SVGA device there is a race period from
 * the time we first read the fence seqno to the time we enable interrupts.
 * If we miss the interrupt for a fence during this period its likely the driver
 * will stall. As a result we need to re-read the seqno after interrupts are
 * enabled. If interrupts were already enabled we just increment the number of
 * seqno waiters.
 */
static bool vmw_fence_enable_signaling(struct dma_fence *f)
{
 u32 seqno;
 struct vmw_fence_obj *fence =
  container_of(f, struct vmw_fence_obj, base);

 struct vmw_fence_manager *fman = fman_from_fence(fence);
 struct vmw_private *dev_priv = fman->dev_priv;
check_for_race:
 seqno = vmw_fence_read(dev_priv);
 if (seqno - fence->base.seqno < VMW_FENCE_WRAP) {
  if (fence->waiter_added) {
   vmw_seqno_waiter_remove(dev_priv);
   fence->waiter_added = false;
  }
  return false;
 } else if (!fence->waiter_added) {
  fence->waiter_added = true;
  if (vmw_seqno_waiter_add(dev_priv))
   goto check_for_race;
 }
 return true;
}

static u32 __vmw_fences_update(struct vmw_fence_manager *fman);

static const struct dma_fence_ops vmw_fence_ops = {
 .get_driver_name = vmw_fence_get_driver_name,
 .get_timeline_name = vmw_fence_get_timeline_name,
 .enable_signaling = vmw_fence_enable_signaling,
 .release = vmw_fence_obj_destroy,
};

struct vmw_fence_manager *vmw_fence_manager_init(struct vmw_private *dev_priv)
{
 struct vmw_fence_manager *fman = kzalloc(sizeof(*fman), GFP_KERNEL);

 if (unlikely(!fman))
  return NULL;

 fman->dev_priv = dev_priv;
 spin_lock_init(&fman->lock);
 INIT_LIST_HEAD(&fman->fence_list);
 fman->fifo_down = true;
 fman->ctx = dma_fence_context_alloc(1);

 return fman;
}

void vmw_fence_manager_takedown(struct vmw_fence_manager *fman)
{
 bool lists_empty;

 spin_lock(&fman->lock);
 lists_empty = list_empty(&fman->fence_list);
 spin_unlock(&fman->lock);

 BUG_ON(!lists_empty);
 kfree(fman);
}

static int vmw_fence_obj_init(struct vmw_fence_manager *fman,
         struct vmw_fence_obj *fence, u32 seqno,
         void (*destroy) (struct vmw_fence_obj *fence))
{
 int ret = 0;

 dma_fence_init(&fence->base, &vmw_fence_ops, &fman->lock,
         fman->ctx, seqno);
 fence->destroy = destroy;

 spin_lock(&fman->lock);
 if (unlikely(fman->fifo_down)) {
  ret = -EBUSY;
  goto out_unlock;
 }
 /* This creates an implicit reference to the fence from the fence
 * manager. It will be dropped when the fence is signaled which is
 * expected to happen before deletion. The dtor has code to catch
 * the rare deletion before signaling case.
 */
 list_add_tail(&fence->head, &fman->fence_list);

out_unlock:
 spin_unlock(&fman->lock);
 return ret;

}

static u32 __vmw_fences_update(struct vmw_fence_manager *fman)
{
 struct vmw_fence_obj *fence, *next_fence;
 const bool cookie = dma_fence_begin_signalling();
 const u32 seqno = vmw_fence_read(fman->dev_priv);

 list_for_each_entry_safe(fence, next_fence, &fman->fence_list, head) {
  if (seqno - fence->base.seqno < VMW_FENCE_WRAP) {
   list_del_init(&fence->head);
   if (fence->waiter_added) {
    vmw_seqno_waiter_remove(fman->dev_priv);
    fence->waiter_added = false;
   }
   dma_fence_signal_locked(&fence->base);
  } else
   break;
 }
 dma_fence_end_signalling(cookie);
 atomic_set_release(&fman->dev_priv->last_read_seqno, seqno);
 return seqno;
}

u32 vmw_fences_update(struct vmw_fence_manager *fman)
{
 u32 seqno;
 spin_lock(&fman->lock);
 seqno = __vmw_fences_update(fman);
 spin_unlock(&fman->lock);
 return seqno;
}

bool vmw_fence_obj_signaled(struct vmw_fence_obj *fence)
{
 struct vmw_fence_manager *fman = fman_from_fence(fence);

 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))
  return true;

 vmw_fences_update(fman);

 return dma_fence_is_signaled(&fence->base);
}

int vmw_fence_obj_wait(struct vmw_fence_obj *fence, bool lazy,
         bool interruptible, unsigned long timeout)
{
 long ret = dma_fence_wait_timeout(&fence->base, interruptible, timeout);

 if (likely(ret > 0))
  return 0;
 else if (ret == 0)
  return -EBUSY;
 else
  return ret;
}

static void vmw_fence_destroy(struct vmw_fence_obj *fence)
{
 dma_fence_free(&fence->base);
}

int vmw_fence_create(struct vmw_fence_manager *fman,
       uint32_t seqno,
       struct vmw_fence_obj **p_fence)
{
 struct vmw_fence_obj *fence;
 int ret;

 fence = kzalloc(sizeof(*fence), GFP_KERNEL);
 if (unlikely(!fence))
  return -ENOMEM;

 ret = vmw_fence_obj_init(fman, fence, seqno, vmw_fence_destroy);
 if (unlikely(ret != 0))
  goto out_err_init;

 *p_fence = fence;
 return 0;

out_err_init:
 kfree(fence);
 return ret;
}


static void vmw_user_fence_destroy(struct vmw_fence_obj *fence)
{
 struct vmw_user_fence *ufence =
  container_of(fence, struct vmw_user_fence, fence);

 ttm_base_object_kfree(ufence, base);
}

static void vmw_user_fence_base_release(struct ttm_base_object **p_base)
{
 struct ttm_base_object *base = *p_base;
 struct vmw_user_fence *ufence =
  container_of(base, struct vmw_user_fence, base);
 struct vmw_fence_obj *fence = &ufence->fence;

 *p_base = NULL;
 vmw_fence_obj_unreference(&fence);
}

int vmw_user_fence_create(struct drm_file *file_priv,
     struct vmw_fence_manager *fman,
     uint32_t seqno,
     struct vmw_fence_obj **p_fence,
     uint32_t *p_handle)
{
 struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
 struct vmw_user_fence *ufence;
 struct vmw_fence_obj *tmp;
 int ret;

 ufence = kzalloc(sizeof(*ufence), GFP_KERNEL);
 if (unlikely(!ufence)) {
  ret = -ENOMEM;
  goto out_no_object;
 }

 ret = vmw_fence_obj_init(fman, &ufence->fence, seqno,
     vmw_user_fence_destroy);
 if (unlikely(ret != 0)) {
  kfree(ufence);
  goto out_no_object;
 }

 /*
 * The base object holds a reference which is freed in
 * vmw_user_fence_base_release.
 */
 tmp = vmw_fence_obj_reference(&ufence->fence);

 ret = ttm_base_object_init(tfile, &ufence->base, false,
       VMW_RES_FENCE,
       &vmw_user_fence_base_release);


 if (unlikely(ret != 0)) {
  /*
 * Free the base object's reference
 */
  vmw_fence_obj_unreference(&tmp);
  goto out_err;
 }

 *p_fence = &ufence->fence;
 *p_handle = ufence->base.handle;

 return 0;
out_err:
 tmp = &ufence->fence;
 vmw_fence_obj_unreference(&tmp);
out_no_object:
 return ret;
}

/*
 * vmw_fence_fifo_down - signal all unsignaled fence objects.
 */

void vmw_fence_fifo_down(struct vmw_fence_manager *fman)
{
 int ret;

 /*
 * The list may be altered while we traverse it, so always
 * restart when we've released the fman->lock.
 */

 spin_lock(&fman->lock);
 fman->fifo_down = true;
 while (!list_empty(&fman->fence_list)) {
  struct vmw_fence_obj *fence =
   list_entry(fman->fence_list.prev, struct vmw_fence_obj,
       head);
  dma_fence_get(&fence->base);
  spin_unlock(&fman->lock);

  ret = vmw_fence_obj_wait(fence, false, false,
      VMW_FENCE_WAIT_TIMEOUT);

  if (unlikely(ret != 0)) {
   list_del_init(&fence->head);
   dma_fence_signal(&fence->base);
  }

  BUG_ON(!list_empty(&fence->head));
  dma_fence_put(&fence->base);
  spin_lock(&fman->lock);
 }
 spin_unlock(&fman->lock);
}

void vmw_fence_fifo_up(struct vmw_fence_manager *fman)
{
 spin_lock(&fman->lock);
 fman->fifo_down = false;
 spin_unlock(&fman->lock);
}


/**
 * vmw_fence_obj_lookup - Look up a user-space fence object
 *
 * @tfile: A struct ttm_object_file identifying the caller.
 * @handle: A handle identifying the fence object.
 * @return: A struct vmw_user_fence base ttm object on success or
 * an error pointer on failure.
 *
 * The fence object is looked up and type-checked. The caller needs
 * to have opened the fence object first, but since that happens on
 * creation and fence objects aren't shareable, that's not an
 * issue currently.
 */
static struct ttm_base_object *
vmw_fence_obj_lookup(struct ttm_object_file *tfile, u32 handle)
{
 struct ttm_base_object *base = ttm_base_object_lookup(tfile, handle);

 if (!base) {
  pr_err("Invalid fence object handle 0x%08lx.\n",
         (unsigned long)handle);
  return ERR_PTR(-EINVAL);
 }

 if (base->refcount_release != vmw_user_fence_base_release) {
  pr_err("Invalid fence object handle 0x%08lx.\n",
         (unsigned long)handle);
  ttm_base_object_unref(&base);
  return ERR_PTR(-EINVAL);
 }

 return base;
}


int vmw_fence_obj_wait_ioctl(struct drm_device *dev, void *data,
        struct drm_file *file_priv)
{
 struct drm_vmw_fence_wait_arg *arg =
     (struct drm_vmw_fence_wait_arg *)data;
 unsigned long timeout;
 struct ttm_base_object *base;
 struct vmw_fence_obj *fence;
 struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
 int ret;
 uint64_t wait_timeout = ((uint64_t)arg->timeout_us * HZ);

 /*
 * 64-bit division not present on 32-bit systems, so do an
 * approximation. (Divide by 1000000).
 */

 wait_timeout = (wait_timeout >> 20) + (wait_timeout >> 24) -
   (wait_timeout >> 26);

 if (!arg->cookie_valid) {
  arg->cookie_valid = 1;
  arg->kernel_cookie = jiffies + wait_timeout;
 }

 base = vmw_fence_obj_lookup(tfile, arg->handle);
 if (IS_ERR(base))
  return PTR_ERR(base);

 fence = &(container_of(base, struct vmw_user_fence, base)->fence);

 timeout = jiffies;
 if (time_after_eq(timeout, (unsigned long)arg->kernel_cookie)) {
  ret = ((vmw_fence_obj_signaled(fence)) ?
         0 : -EBUSY);
  goto out;
 }

 timeout = (unsigned long)arg->kernel_cookie - timeout;

 ret = vmw_fence_obj_wait(fence, arg->lazy, true, timeout);

out:
 ttm_base_object_unref(&base);

 /*
 * Optionally unref the fence object.
 */

 if (ret == 0 && (arg->wait_options & DRM_VMW_WAIT_OPTION_UNREF))
  return ttm_ref_object_base_unref(tfile, arg->handle);
 return ret;
}

int vmw_fence_obj_signaled_ioctl(struct drm_device *dev, void *data,
     struct drm_file *file_priv)
{
 struct drm_vmw_fence_signaled_arg *arg =
  (struct drm_vmw_fence_signaled_arg *) data;
 struct ttm_base_object *base;
 struct vmw_fence_obj *fence;
 struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
 struct vmw_private *dev_priv = vmw_priv(dev);

 base = vmw_fence_obj_lookup(tfile, arg->handle);
 if (IS_ERR(base))
  return PTR_ERR(base);

 fence = &(container_of(base, struct vmw_user_fence, base)->fence);

 arg->signaled = vmw_fence_obj_signaled(fence);

 arg->signaled_flags = arg->flags;
 arg->passed_seqno = atomic_read_acquire(&dev_priv->last_read_seqno);

 ttm_base_object_unref(&base);

 return 0;
}


int vmw_fence_obj_unref_ioctl(struct drm_device *dev, void *data,
         struct drm_file *file_priv)
{
 struct drm_vmw_fence_arg *arg =
  (struct drm_vmw_fence_arg *) data;

 return ttm_ref_object_base_unref(vmw_fpriv(file_priv)->tfile,
      arg->handle);
}

/**
 * vmw_event_fence_action_seq_passed
 *
 * @action: The struct vmw_fence_action embedded in a struct
 * vmw_event_fence_action.
 *
 * This function is called when the seqno of the fence where @action is
 * attached has passed. It queues the event on the submitter's event list.
 * This function is always called from atomic context.
 */
static void vmw_event_fence_action_seq_passed(struct dma_fence *f,
           struct dma_fence_cb *cb)
{
 struct vmw_event_fence_action *eaction =
  container_of(cb, struct vmw_event_fence_action, base);
 struct drm_device *dev = eaction->dev;
 struct drm_pending_event *event = eaction->event;

 if (unlikely(event == NULL))
  return;

 spin_lock_irq(&dev->event_lock);

 if (likely(eaction->tv_sec != NULL)) {
  struct timespec64 ts;

  ts = ktime_to_timespec64(f->timestamp);
  /* monotonic time, so no y2038 overflow */
  *eaction->tv_sec = ts.tv_sec;
  *eaction->tv_usec = ts.tv_nsec / NSEC_PER_USEC;
 }

 drm_send_event_locked(dev, eaction->event);
 eaction->event = NULL;
 spin_unlock_irq(&dev->event_lock);
 dma_fence_put(f);
 kfree(eaction);
}

/**
 * vmw_event_fence_action_queue - Post an event for sending when a fence
 * object seqno has passed.
 *
 * @file_priv: The file connection on which the event should be posted.
 * @fence: The fence object on which to post the event.
 * @event: Event to be posted. This event should've been alloced
 * using k[mz]alloc, and should've been completely initialized.
 * @tv_sec: If non-null, the variable pointed to will be assigned
 * current time tv_sec val when the fence signals.
 * @tv_usec: Must be set if @tv_sec is set, and the variable pointed to will
 * be assigned the current time tv_usec val when the fence signals.
 * @interruptible: Interruptible waits if possible.
 *
 * As a side effect, the object pointed to by @event may have been
 * freed when this function returns. If this function returns with
 * an error code, the caller needs to free that object.
 */

int vmw_event_fence_action_queue(struct drm_file *file_priv,
     struct vmw_fence_obj *fence,
     struct drm_pending_event *event,
     uint32_t *tv_sec,
     uint32_t *tv_usec,
     bool interruptible)
{
 struct vmw_event_fence_action *eaction;
 struct vmw_fence_manager *fman = fman_from_fence(fence);

 eaction = kzalloc(sizeof(*eaction), GFP_KERNEL);
 if (unlikely(!eaction))
  return -ENOMEM;

 eaction->event = event;
 eaction->dev = &fman->dev_priv->drm;
 eaction->tv_sec = tv_sec;
 eaction->tv_usec = tv_usec;

 vmw_fence_obj_reference(fence); // Dropped in CB
 if (dma_fence_add_callback(&fence->base, &eaction->base,
       vmw_event_fence_action_seq_passed) < 0)
  vmw_event_fence_action_seq_passed(&fence->base, &eaction->base);
 return 0;
}

struct vmw_event_fence_pending {
 struct drm_pending_event base;
 struct drm_vmw_event_fence event;
};

static int vmw_event_fence_action_create(struct drm_file *file_priv,
      struct vmw_fence_obj *fence,
      uint32_t flags,
      uint64_t user_data,
      bool interruptible)
{
 struct vmw_event_fence_pending *event;
 struct vmw_fence_manager *fman = fman_from_fence(fence);
 struct drm_device *dev = &fman->dev_priv->drm;
 int ret;

 event = kzalloc(sizeof(*event), GFP_KERNEL);
 if (unlikely(!event)) {
  DRM_ERROR("Failed to allocate an event.\n");
  ret = -ENOMEM;
  goto out_no_space;
 }

 event->event.base.type = DRM_VMW_EVENT_FENCE_SIGNALED;
 event->event.base.length = sizeof(event->event);
 event->event.user_data = user_data;

 ret = drm_event_reserve_init(dev, file_priv, &event->base, &event->event.base);

 if (unlikely(ret != 0)) {
  DRM_ERROR("Failed to allocate event space for this file.\n");
  kfree(event);
  goto out_no_space;
 }

 if (flags & DRM_VMW_FE_FLAG_REQ_TIME)
  ret = vmw_event_fence_action_queue(file_priv, fence,
         &event->base,
         &event->event.tv_sec,
         &event->event.tv_usec,
         interruptible);
 else
  ret = vmw_event_fence_action_queue(file_priv, fence,
         &event->base,
         NULL,
         NULL,
         interruptible);
 if (ret != 0)
  goto out_no_queue;

 return 0;

out_no_queue:
 drm_event_cancel_free(dev, &event->base);
out_no_space:
 return ret;
}

int vmw_fence_event_ioctl(struct drm_device *dev, void *data,
     struct drm_file *file_priv)
{
 struct vmw_private *dev_priv = vmw_priv(dev);
 struct drm_vmw_fence_event_arg *arg =
  (struct drm_vmw_fence_event_arg *) data;
 struct vmw_fence_obj *fence = NULL;
 struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
 struct ttm_object_file *tfile = vmw_fp->tfile;
 struct drm_vmw_fence_rep __user *user_fence_rep =
  (struct drm_vmw_fence_rep __user *)(unsigned long)
  arg->fence_rep;
 uint32_t handle;
 int ret;

 /*
 * Look up an existing fence object,
 * and if user-space wants a new reference,
 * add one.
 */
 if (arg->handle) {
  struct ttm_base_object *base =
   vmw_fence_obj_lookup(tfile, arg->handle);

  if (IS_ERR(base))
   return PTR_ERR(base);

  fence = &(container_of(base, struct vmw_user_fence,
           base)->fence);
  (void) vmw_fence_obj_reference(fence);

  if (user_fence_rep != NULL) {
   ret = ttm_ref_object_add(vmw_fp->tfile, base,
       NULL, false);
   if (unlikely(ret != 0)) {
    DRM_ERROR("Failed to reference a fence "
       "object.\n");
    goto out_no_ref_obj;
   }
   handle = base->handle;
  }
  ttm_base_object_unref(&base);
 }

 /*
 * Create a new fence object.
 */
 if (!fence) {
  ret = vmw_execbuf_fence_commands(file_priv, dev_priv,
       &fence,
       (user_fence_rep) ?
       &handle : NULL);
  if (unlikely(ret != 0)) {
   DRM_ERROR("Fence event failed to create fence.\n");
   return ret;
  }
 }

 BUG_ON(fence == NULL);

 ret = vmw_event_fence_action_create(file_priv, fence,
         arg->flags,
         arg->user_data,
         true);
 if (unlikely(ret != 0)) {
  if (ret != -ERESTARTSYS)
   DRM_ERROR("Failed to attach event to fence.\n");
  goto out_no_create;
 }

 vmw_execbuf_copy_fence_user(dev_priv, vmw_fp, 0, user_fence_rep, fence,
        handle, -1);
 vmw_fence_obj_unreference(&fence);
 return 0;
out_no_create:
 if (user_fence_rep != NULL)
  ttm_ref_object_base_unref(tfile, handle);
out_no_ref_obj:
 vmw_fence_obj_unreference(&fence);
 return ret;
}