Merge tag 'drm-misc-next-2021-09-16' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

drm-misc-next for $kernel-version:

UAPI Changes:

Cross-subsystem Changes:
  - dma-buf: Avoid a warning with some allocations, Remove
    DMA_FENCE_TRACE macros

Core Changes:
  - bridge: New helper to git rid of panels in drivers
  - fence: Improve dma_fence_add_callback documentation, Improve
    dma_fence_ops->wait documentation
  - ioctl: Unexport drm_ioctl_permit
  - lease: Documentation improvements
  - fourcc: Add new macro to determine the modifier vendor
  - quirks: Add the Steam Deck, Chuwi HiBook, Chuwi Hi10 Pro, Samsung
    Galaxy Book 10.6, KD Kurio Smart C15200 2-in-1, Lenovo Ideapad D330
  - resv: Improve the documentation
  - shmem-helpers: Allocate WC pages on x86, Switch to vmf_insert_pfn
  - sched: Fix for a timer being canceled too soon, Avoid null pointer
    derefence if the fence is null in drm_sched_fence_free, Convert
    drivers to rely on its dependency tracking
  - ttm: Switch to kerneldoc, new helper to clear all DMA mappings, pool
    shrinker optitimization, Remove ttm_tt_destroy_common, Fix for
    unbinding on multiple drivers

Driver Changes:
  - bochs: New PCI IDs
  - msm: Fence ordering impromevemnts
  - stm: Add layer alpha support, zpos
  - v3d: Fix for a Vulkan CTS failure
  - vc4: Conversion to the new bridge helpers
  - vgem: Use shmem helpers
  - virtio: Support mapping exported vram
  - zte: Remove obsolete driver

  - bridge: Probe improvements for it66121, enable DSI EOTP for anx7625,
    errors propagation improvements for anx7625

  - panels: 60fps mode for otm8009a, New driver for Samsung S6D27A1

Signed-off-by: Dave Airlie <airlied@redhat.com>

# gpg: Signature made Thu 16 Sep 2021 17:30:50 AEST
# gpg:                using EDDSA key 5C1337A45ECA9AEB89060E9EE3EF0D6F671851C5
# gpg: Can't check signature: No public key
From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210916073132.ptbbmjetm7v3ufq3@gilmour

5 files changed, 110 insertions, 143 deletions

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 8b32b4bdd590..66470c37e471 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -420,6 +420,13 @@ struct dma_buf {
 	 * - Dynamic importers should set fences for any access that they can't
 	 *   disable immediately from their &dma_buf_attach_ops.move_notify
 	 *   callback.
+	 *
+	 * IMPORTANT:
+	 *
+	 * All drivers must obey the struct dma_resv rules, specifically the
+	 * rules for updating fences, see &dma_resv.fence_excl and
+	 * &dma_resv.fence. If these dependency rules are broken access tracking
+	 * can be lost resulting in use after free issues.
 	 */
 	struct dma_resv *resv;
 
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 6ffb4b2c6371..a706b7bf51d7 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -214,19 +214,15 @@ struct dma_fence_ops {
 	 * Custom wait implementation, defaults to dma_fence_default_wait() if
 	 * not set.
 	 *
-	 * The dma_fence_default_wait implementation should work for any fence, as long
-	 * as @enable_signaling works correctly. This hook allows drivers to
-	 * have an optimized version for the case where a process context is
-	 * already available, e.g. if @enable_signaling for the general case
-	 * needs to set up a worker thread.
+	 * Deprecated and should not be used by new implementations. Only used
+	 * by existing implementations which need special handling for their
+	 * hardware reset procedure.
 	 *
 	 * Must return -ERESTARTSYS if the wait is intr = true and the wait was
 	 * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
 	 * timed out. Can also return other error values on custom implementations,
 	 * which should be treated as if the fence is signaled. For example a hardware
 	 * lockup could be reported like that.
-	 *
-	 * This callback is optional.
 	 */
 	signed long (*wait)(struct dma_fence *fence,
 			    bool intr, signed long timeout);
@@ -590,26 +586,4 @@ struct dma_fence *dma_fence_get_stub(void);
 struct dma_fence *dma_fence_allocate_private_stub(void);
 u64 dma_fence_context_alloc(unsigned num);
 
-#define DMA_FENCE_TRACE(f, fmt, args...) \
-	do {								\
-		struct dma_fence *__ff = (f);				\
-		if (IS_ENABLED(CONFIG_DMA_FENCE_TRACE))			\
-			pr_info("f %llu#%llu: " fmt,			\
-				__ff->context, __ff->seqno, ##args);	\
-	} while (0)
-
-#define DMA_FENCE_WARN(f, fmt, args...) \
-	do {								\
-		struct dma_fence *__ff = (f);				\
-		pr_warn("f %llu#%llu: " fmt, __ff->context, __ff->seqno,\
-			 ##args);					\
-	} while (0)
-
-#define DMA_FENCE_ERR(f, fmt, args...) \
-	do {								\
-		struct dma_fence *__ff = (f);				\
-		pr_err("f %llu#%llu: " fmt, __ff->context, __ff->seqno,	\
-			##args);					\
-	} while (0)
-
 #endif /* __LINUX_DMA_FENCE_H */
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index e1ca2080a1ff..9100dd3dc21f 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -62,16 +62,90 @@ struct dma_resv_list {
 
 /**
  * struct dma_resv - a reservation object manages fences for a buffer
- * @lock: update side lock
- * @seq: sequence count for managing RCU read-side synchronization
- * @fence_excl: the exclusive fence, if there is one currently
- * @fence: list of current shared fences
+ *
+ * There are multiple uses for this, with sometimes slightly different rules in
+ * how the fence slots are used.
+ *
+ * One use is to synchronize cross-driver access to a struct dma_buf, either for
+ * dynamic buffer management or just to handle implicit synchronization between
+ * different users of the buffer in userspace. See &dma_buf.resv for a more
+ * in-depth discussion.
+ *
+ * The other major use is to manage access and locking within a driver in a
+ * buffer based memory manager. struct ttm_buffer_object is the canonical
+ * example here, since this is where reservation objects originated from. But
+ * use in drivers is spreading and some drivers also manage struct
+ * drm_gem_object with the same scheme.
  */
 struct dma_resv {
+	/**
+	 * @lock:
+	 *
+	 * Update side lock. Don't use directly, instead use the wrapper
+	 * functions like dma_resv_lock() and dma_resv_unlock().
+	 *
+	 * Drivers which use the reservation object to manage memory dynamically
+	 * also use this lock to protect buffer object state like placement,
+	 * allocation policies or throughout command submission.
+	 */
 	struct ww_mutex lock;
+
+	/**
+	 * @seq:
+	 *
+	 * Sequence count for managing RCU read-side synchronization, allows
+	 * read-only access to @fence_excl and @fence while ensuring we take a
+	 * consistent snapshot.
+	 */
 	seqcount_ww_mutex_t seq;
 
+	/**
+	 * @fence_excl:
+	 *
+	 * The exclusive fence, if there is one currently.
+	 *
+	 * There are two ways to update this fence:
+	 *
+	 * - First by calling dma_resv_add_excl_fence(), which replaces all
+	 *   fences attached to the reservation object. To guarantee that no
+	 *   fences are lost, this new fence must signal only after all previous
+	 *   fences, both shared and exclusive, have signalled. In some cases it
+	 *   is convenient to achieve that by attaching a struct dma_fence_array
+	 *   with all the new and old fences.
+	 *
+	 * - Alternatively the fence can be set directly, which leaves the
+	 *   shared fences unchanged. To guarantee that no fences are lost, this
+	 *   new fence must signal only after the previous exclusive fence has
+	 *   signalled. Since the shared fences are staying intact, it is not
+	 *   necessary to maintain any ordering against those. If semantically
+	 *   only a new access is added without actually treating the previous
+	 *   one as a dependency the exclusive fences can be strung together
+	 *   using struct dma_fence_chain.
+	 *
+	 * Note that actual semantics of what an exclusive or shared fence mean
+	 * is defined by the user, for reservation objects shared across drivers
+	 * see &dma_buf.resv.
+	 */
 	struct dma_fence __rcu *fence_excl;
+
+	/**
+	 * @fence:
+	 *
+	 * List of current shared fences.
+	 *
+	 * There are no ordering constraints of shared fences against the
+	 * exclusive fence slot. If a waiter needs to wait for all access, it
+	 * has to wait for both sets of fences to signal.
+	 *
+	 * A new fence is added by calling dma_resv_add_shared_fence(). Since
+	 * this often needs to be done past the point of no return in command
+	 * submission it cannot fail, and therefore sufficient slots need to be
+	 * reserved by calling dma_resv_reserve_shared().
+	 *
+	 * Note that actual semantics of what an exclusive or shared fence mean
+	 * is defined by the user, for reservation objects shared across drivers
+	 * see &dma_buf.resv.
+	 */
 	struct dma_resv_list __rcu *fence;
 };
 
@@ -98,6 +172,13 @@ static inline void dma_resv_reset_shared_max(struct dma_resv *obj) {}
  * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
  * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
  * object may be locked by itself by passing NULL as @ctx.
+ *
+ * When a die situation is indicated by returning -EDEADLK all locks held by
+ * @ctx must be unlocked and then dma_resv_lock_slow() called on @obj.
+ *
+ * Unlocked by calling dma_resv_unlock().
+ *
+ * See also dma_resv_lock_interruptible() for the interruptible variant.
  */
 static inline int dma_resv_lock(struct dma_resv *obj,
 				struct ww_acquire_ctx *ctx)
@@ -119,6 +200,12 @@ static inline int dma_resv_lock(struct dma_resv *obj,
  * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
  * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
  * object may be locked by itself by passing NULL as @ctx.
+ *
+ * When a die situation is indicated by returning -EDEADLK all locks held by
+ * @ctx must be unlocked and then dma_resv_lock_slow_interruptible() called on
+ * @obj.
+ *
+ * Unlocked by calling dma_resv_unlock().
  */
 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
 					      struct ww_acquire_ctx *ctx)
@@ -134,6 +221,8 @@ static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
  * Acquires the reservation object after a die case. This function
  * will sleep until the lock becomes available. See dma_resv_lock() as
  * well.
+ *
+ * See also dma_resv_lock_slow_interruptible() for the interruptible variant.
  */
 static inline void dma_resv_lock_slow(struct dma_resv *obj,
 				      struct ww_acquire_ctx *ctx)
@@ -167,7 +256,7 @@ static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
  * if they overlap with a writer.
  *
  * Also note that since no context is provided, no deadlock protection is
- * possible.
+ * possible, which is also not needed for a trylock.
  *
  * Returns true if the lock was acquired, false otherwise.
  */
@@ -193,6 +282,11 @@ static inline bool dma_resv_is_locked(struct dma_resv *obj)
  *
  * Returns the context used to lock a reservation object or NULL if no context
  * was used or the object is not locked at all.
+ *
+ * WARNING: This interface is pretty horrible, but TTM needs it because it
+ * doesn't pass the struct ww_acquire_ctx around in some very long callchains.
+ * Everyone else just uses it to check whether they're holding a reservation or
+ * not.
  */
 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
 {
diff --git a/include/linux/seqno-fence.h b/include/linux/seqno-fence.h
deleted file mode 100644
index 3cca2b8fac43..000000000000
--- a/include/linux/seqno-fence.h
+++ /dev/null
@@ -1,109 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * seqno-fence, using a dma-buf to synchronize fencing
- *
- * Copyright (C) 2012 Texas Instruments
- * Copyright (C) 2012 Canonical Ltd
- * Authors:
- *   Rob Clark <robdclark@gmail.com>
- *   Maarten Lankhorst <maarten.lankhorst@canonical.com>
- */
-
-#ifndef __LINUX_SEQNO_FENCE_H
-#define __LINUX_SEQNO_FENCE_H
-
-#include <linux/dma-fence.h>
-#include <linux/dma-buf.h>
-
-enum seqno_fence_condition {
-	SEQNO_FENCE_WAIT_GEQUAL,
-	SEQNO_FENCE_WAIT_NONZERO
-};
-
-struct seqno_fence {
-	struct dma_fence base;
-
-	const struct dma_fence_ops *ops;
-	struct dma_buf *sync_buf;
-	uint32_t seqno_ofs;
-	enum seqno_fence_condition condition;
-};
-
-extern const struct dma_fence_ops seqno_fence_ops;
-
-/**
- * to_seqno_fence - cast a fence to a seqno_fence
- * @fence: fence to cast to a seqno_fence
- *
- * Returns NULL if the fence is not a seqno_fence,
- * or the seqno_fence otherwise.
- */
-static inline struct seqno_fence *
-to_seqno_fence(struct dma_fence *fence)
-{
-	if (fence->ops != &seqno_fence_ops)
-		return NULL;
-	return container_of(fence, struct seqno_fence, base);
-}
-
-/**
- * seqno_fence_init - initialize a seqno fence
- * @fence: seqno_fence to initialize
- * @lock: pointer to spinlock to use for fence
- * @sync_buf: buffer containing the memory location to signal on
- * @context: the execution context this fence is a part of
- * @seqno_ofs: the offset within @sync_buf
- * @seqno: the sequence # to signal on
- * @cond: fence wait condition
- * @ops: the fence_ops for operations on this seqno fence
- *
- * This function initializes a struct seqno_fence with passed parameters,
- * and takes a reference on sync_buf which is released on fence destruction.
- *
- * A seqno_fence is a dma_fence which can complete in software when
- * enable_signaling is called, but it also completes when
- * (s32)((sync_buf)[seqno_ofs] - seqno) >= 0 is true
- *
- * The seqno_fence will take a refcount on the sync_buf until it's
- * destroyed, but actual lifetime of sync_buf may be longer if one of the
- * callers take a reference to it.
- *
- * Certain hardware have instructions to insert this type of wait condition
- * in the command stream, so no intervention from software would be needed.
- * This type of fence can be destroyed before completed, however a reference
- * on the sync_buf dma-buf can be taken. It is encouraged to re-use the same
- * dma-buf for sync_buf, since mapping or unmapping the sync_buf to the
- * device's vm can be expensive.
- *
- * It is recommended for creators of seqno_fence to call dma_fence_signal()
- * before destruction. This will prevent possible issues from wraparound at
- * time of issue vs time of check, since users can check dma_fence_is_signaled()
- * before submitting instructions for the hardware to wait on the fence.
- * However, when ops.enable_signaling is not called, it doesn't have to be
- * done as soon as possible, just before there's any real danger of seqno
- * wraparound.
- */
-static inline void
-seqno_fence_init(struct seqno_fence *fence, spinlock_t *lock,
-		 struct dma_buf *sync_buf,  uint32_t context,
-		 uint32_t seqno_ofs, uint32_t seqno,
-		 enum seqno_fence_condition cond,
-		 const struct dma_fence_ops *ops)
-{
-	BUG_ON(!fence || !sync_buf || !ops);
-	BUG_ON(!ops->wait || !ops->enable_signaling ||
-	       !ops->get_driver_name || !ops->get_timeline_name);
-
-	/*
-	 * ops is used in dma_fence_init for get_driver_name, so needs to be
-	 * initialized first
-	 */
-	fence->ops = ops;
-	dma_fence_init(&fence->base, &seqno_fence_ops, lock, context, seqno);
-	get_dma_buf(sync_buf);
-	fence->sync_buf = sync_buf;
-	fence->seqno_ofs = seqno_ofs;
-	fence->condition = cond;
-}
-
-#endif /* __LINUX_SEQNO_FENCE_H */
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 9814fff58a69..76fbf92b04d9 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -93,4 +93,5 @@ extern void register_shrinker_prepared(struct shrinker *shrinker);
 extern int register_shrinker(struct shrinker *shrinker);
 extern void unregister_shrinker(struct shrinker *shrinker);
 extern void free_prealloced_shrinker(struct shrinker *shrinker);
+extern void synchronize_shrinkers(void);
 #endif