Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <cd0d07be-9534-52c8-7b2d-6ab70dae7198@redhat.com>
Date:   Thu, 6 Jul 2023 17:48:36 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.12.0
Subject: Re: [PATCH drm-next v6 02/13] drm: manager to keep track of GPUs VA
 mappings
Content-Language: en-US
To:     =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28Intel=29?= 
        <thomas_os@shipmail.org>
Cc:     airlied@gmail.com, daniel@ffwll.ch, tzimmermann@suse.de,
        mripard@kernel.org, corbet@lwn.net, christian.koenig@amd.com,
        bskeggs@redhat.com, Liam.Howlett@oracle.com,
        matthew.brost@intel.com, boris.brezillon@collabora.com,
        alexdeucher@gmail.com, ogabbay@kernel.org, bagasdotme@gmail.com,
        willy@infradead.org, jason@jlekstrand.net,
        linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Donald Robson <donald.robson@imgtec.com>,
        Dave Airlie <airlied@redhat.com>
References: <20230629222651.3196-1-dakr@redhat.com>
 <20230629222651.3196-3-dakr@redhat.com>
 <2a8a420c-a628-e34c-c732-0bd1bcb52a84@shipmail.org>
From:   Danilo Krummrich <dakr@redhat.com>
Organization: RedHat
In-Reply-To: <2a8a420c-a628-e34c-c732-0bd1bcb52a84@shipmail.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hi Thomas,

On 7/6/23 10:49, Thomas Hellström (Intel) wrote:
> Hi, Danilo
> 
> Some review comments below:
> 
> On 6/30/23 00:25, Danilo Krummrich wrote:
>> Add infrastructure to keep track of GPU virtual address (VA) mappings
>> with a decicated VA space manager implementation.
>>
>> New UAPIs, motivated by Vulkan sparse memory bindings graphics drivers
>> start implementing, allow userspace applications to request multiple and
>> arbitrary GPU VA mappings of buffer objects. The DRM GPU VA manager is
>> intended to serve the following purposes in this context.
>>
>> 1) Provide infrastructure to track GPU VA allocations and mappings,
>>     making use of the maple_tree.
> 
> It looks like we're not using the maple tree anymore, but rather an 
> instantiation of an interval tree.
> 
> (Perhaps as a follow-up it makes sense to provide a pre-instantiated 
> common u64 version of the interval tree in addition to the unsigned long 
> one since it appears to be used in multiple places in graphics drivers).
> 
>> 2) Generically connect GPU VA mappings to their backing buffers, in
>>     particular DRM GEM objects.
>>
>> 3) Provide a common implementation to perform more complex mapping
>>     operations on the GPU VA space. In particular splitting and merging
>>     of GPU VA mappings, e.g. for intersecting mapping requests or partial
>>     unmap requests.
>>
>> Tested-by: Donald Robson<donald.robson@imgtec.com>
>> Reviewed-by: Boris Brezillon<boris.brezillon@collabora.com>
>> Suggested-by: Dave Airlie<airlied@redhat.com>
>> Signed-off-by: Danilo Krummrich<dakr@redhat.com>
>> ---
>>   Documentation/gpu/drm-mm.rst    |   36 +
>>   drivers/gpu/drm/Makefile        |    1 +
>>   drivers/gpu/drm/drm_gem.c       |    3 +
>>   drivers/gpu/drm/drm_gpuva_mgr.c | 1743 +++++++++++++++++++++++++++++++
>>   include/drm/drm_drv.h           |    6 +
>>   include/drm/drm_gem.h           |   52 +
>>   include/drm/drm_gpuva_mgr.h     |  756 ++++++++++++++
>>   7 files changed, 2597 insertions(+)
>>   create mode 100644 drivers/gpu/drm/drm_gpuva_mgr.c
>>   create mode 100644 include/drm/drm_gpuva_mgr.h
>>
>> diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst
>> index a52e6f4117d6..3d5dc9dc1bfe 100644
>> --- a/Documentation/gpu/drm-mm.rst
>> +++ b/Documentation/gpu/drm-mm.rst
>> @@ -466,6 +466,42 @@ DRM MM Range Allocator Function References
>>   .. kernel-doc:: drivers/gpu/drm/drm_mm.c
>>      :export:
>> +DRM GPU VA Manager
>> +==================
>> +
>> +Overview
>> +--------
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_gpuva_mgr.c
>> +   :doc: Overview
>> +
>> +Split and Merge
>> +---------------
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_gpuva_mgr.c
>> +   :doc: Split and Merge
>> +
>> +Locking
>> +-------
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_gpuva_mgr.c
>> +   :doc: Locking
>> +
>> +Examples
>> +--------
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_gpuva_mgr.c
>> +   :doc: Examples
>> +
>> +DRM GPU VA Manager Function References
>> +--------------------------------------
>> +
>> +.. kernel-doc:: include/drm/drm_gpuva_mgr.h
>> +   :internal:
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_gpuva_mgr.c
>> +   :export:
>> +
>>   DRM Buddy Allocator
>>   ===================
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index 414855e2a463..6d6c9dec66e8 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -45,6 +45,7 @@ drm-y := \
>>       drm_vblank.o \
>>       drm_vblank_work.o \
>>       drm_vma_manager.o \
>> +    drm_gpuva_mgr.o \
>>       drm_writeback.o
>>   drm-$(CONFIG_DRM_LEGACY) += \
>>       drm_agpsupport.o \
>> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
>> index 1a5a2cd0d4ec..cd878ebddbd0 100644
>> --- a/drivers/gpu/drm/drm_gem.c
>> +++ b/drivers/gpu/drm/drm_gem.c
>> @@ -164,6 +164,9 @@ void drm_gem_private_object_init(struct drm_device 
>> *dev,
>>       if (!obj->resv)
>>           obj->resv = &obj->_resv;
>> +    if (drm_core_check_feature(dev, DRIVER_GEM_GPUVA))
>> +        drm_gem_gpuva_init(obj);
>> +
>>       drm_vma_node_reset(&obj->vma_node);
>>       INIT_LIST_HEAD(&obj->lru_node);
>>   }
>> diff --git a/drivers/gpu/drm/drm_gpuva_mgr.c 
>> b/drivers/gpu/drm/drm_gpuva_mgr.c
>> new file mode 100644
>> index 000000000000..4414990c05cc
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_gpuva_mgr.c
>> @@ -0,0 +1,1743 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
> SPDX-License is GPL-2.0 but below looks like MIT. Can we use "GPL-2.0 OR 
> MIT" or does something restrict it to GPL-only?
>> + * Copyright (c) 2022 Red Hat.
>> + *
>> + * 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, 
>> sublicense,
>> + * 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 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 NONINFRINGEMENT.  IN NO EVENT 
>> SHALL
>> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) 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.
>> + *
>> + * Authors:
>> + *     Danilo Krummrich<dakr@redhat.com>
>> + *
>> + */
>> +
>> +#include <drm/drm_gpuva_mgr.h>
>> +
>> +#include <linux/interval_tree_generic.h>
>> +#include <linux/mm.h>
>> +
>> +/**
>> + * DOC: Overview
>> + *
>> + * The DRM GPU VA Manager, represented by struct drm_gpuva_manager 
>> keeps track
>> + * of a GPU's virtual address (VA) space and manages the 
>> corresponding virtual
>> + * mappings represented by &drm_gpuva objects. It also keeps track of 
>> the
>> + * mapping's backing &drm_gem_object buffers.
>> + *
>> + * &drm_gem_object buffers maintain a list of &drm_gpuva objects 
>> representing
>> + * all existent GPU VA mappings using this &drm_gem_object as backing 
>> buffer.
>> + *
>> + * GPU VAs can be flagged as sparse, such that drivers may use GPU 
>> VAs to also
>> + * keep track of sparse PTEs in order to support Vulkan 'Sparse 
>> Resources'.
>> + *
>> + * The GPU VA manager internally uses a rb-tree to manage the
>> + * &drm_gpuva mappings within a GPU's virtual address space.
>> + *
>> + * The &drm_gpuva_manager contains a special &drm_gpuva representing the
>> + * portion of VA space reserved by the kernel. This node is 
>> initialized together
>> + * with the GPU VA manager instance and removed when the GPU VA 
>> manager is
>> + * destroyed.
>> + *
>> + * In a typical application drivers would embed struct 
>> drm_gpuva_manager and
>> + * struct drm_gpuva within their own driver specific structures, 
>> there won't be
>> + * any memory allocations of it's own nor memory allocations of 
>> &drm_gpuva
> s/it's/its/
>> + * entries.
>> + *
>> + * The data structures needed to store &drm_gpuvas within the 
>> &drm_gpuva_manager
>> + * are contained within struct drm_gpuva already. Hence, for inserting
>> + * &drm_gpuva entries from within dma-fence signalling critical 
>> sections it is
>> + * enough to pre-allocate the &drm_gpuva structures.
>> + */
>> +
>> +/**
>> + * DOC: Split and Merge
>> + *
>> + * Besides it's capability to manage and represent a GPU VA space, the
> s/it's/its/
>> + * &drm_gpuva_manager also provides functions to let the 
>> &drm_gpuva_manager
>> + * calculate a sequence of operations to satisfy a given map or unmap 
>> request.
>> + *
>> + * Therefore the DRM GPU VA manager provides an algorithm 
>> implementing splitting
>> + * and merging of existent GPU VA mappings with the ones that are 
>> requested to
>> + * be mapped or unmapped. This feature is required by the Vulkan API to
>> + * implement Vulkan 'Sparse Memory Bindings' - drivers UAPIs often 
>> refer to this
>> + * as VM BIND.
>> + *
>> + * Drivers can call drm_gpuva_sm_map() to receive a sequence of 
>> callbacks
>> + * containing map, unmap and remap operations for a given newly 
>> requested
>> + * mapping. The sequence of callbacks represents the set of 
>> operations to
>> + * execute in order to integrate the new mapping cleanly into the 
>> current state
>> + * of the GPU VA space.
>> + *
>> + * Depending on how the new GPU VA mapping intersects with the 
>> existent mappings
>> + * of the GPU VA space the &drm_gpuva_fn_ops callbacks contain an 
>> arbitrary
>> + * amount of unmap operations, a maximum of two remap operations and 
>> a single
>> + * map operation. The caller might receive no callback at all if no 
>> operation is
>> + * required, e.g. if the requested mapping already exists in the 
>> exact same way.
>> + *
>> + * The single map operation represents the original map operation 
>> requested by
>> + * the caller.
>> + *
>> + * &drm_gpuva_op_unmap contains a 'keep' field, which indicates 
>> whether the
>> + * &drm_gpuva to unmap is physically contiguous with the original 
>> mapping
>> + * request. Optionally, if 'keep' is set, drivers may keep the actual 
>> page table
>> + * entries for this &drm_gpuva, adding the missing page table entries 
>> only and
>> + * update the &drm_gpuva_manager's view of things accordingly.
>> + *
>> + * Drivers may do the same optimization, namely delta page table 
>> updates, also
>> + * for remap operations. This is possible since &drm_gpuva_op_remap 
>> consists of
>> + * one unmap operation and one or two map operations, such that 
>> drivers can
>> + * derive the page table update delta accordingly.
>> + *
>> + * Note that there can't be more than two existent mappings to split 
>> up, one at
>> + * the beginning and one at the end of the new mapping, hence there is a
>> + * maximum of two remap operations.
>> + *
>> + * Analogous to drm_gpuva_sm_map() drm_gpuva_sm_unmap() uses 
>> &drm_gpuva_fn_ops
>> + * to call back into the driver in order to unmap a range of GPU VA 
>> space. The
>> + * logic behind this function is way simpler though: For all existent 
>> mappings
>> + * enclosed by the given range unmap operations are created. For 
>> mappings which
>> + * are only partically located within the given range, remap 
>> operations are
>> + * created such that those mappings are split up and re-mapped 
>> partically.
>> + *
>> + * As an alternative to drm_gpuva_sm_map() and drm_gpuva_sm_unmap(),
>> + * drm_gpuva_sm_map_ops_create() and drm_gpuva_sm_unmap_ops_create() 
>> can be used
>> + * to directly obtain an instance of struct drm_gpuva_ops containing 
>> a list of
>> + * &drm_gpuva_op, which can be iterated with drm_gpuva_for_each_op(). 
>> This list
>> + * contains the &drm_gpuva_ops analogous to the callbacks one would 
>> receive when
>> + * calling drm_gpuva_sm_map() or drm_gpuva_sm_unmap(). While this way 
>> requires
>> + * more memory (to allocate the &drm_gpuva_ops), it provides drivers 
>> a way to
>> + * iterate the &drm_gpuva_op multiple times, e.g. once in a context 
>> where memory
>> + * allocations are possible (e.g. to allocate GPU page tables) and 
>> once in the
>> + * dma-fence signalling critical path.
>> + *
>> + * To update the &drm_gpuva_manager's view of the GPU VA space
>> + * drm_gpuva_insert() and drm_gpuva_remove() may be used. These 
>> functions can
>> + * safely be used from &drm_gpuva_fn_ops callbacks originating from
>> + * drm_gpuva_sm_map() or drm_gpuva_sm_unmap(). However, it might be more
>> + * convenient to use the provided helper functions drm_gpuva_map(),
>> + * drm_gpuva_remap() and drm_gpuva_unmap() instead.
>> + *
>> + * The following diagram depicts the basic relationships of existent 
>> GPU VA
>> + * mappings, a newly requested mapping and the resulting mappings as 
>> implemented
>> + * by drm_gpuva_sm_map() - it doesn't cover any arbitrary 
>> combinations of these.
>> + *
>> + * 1) Requested mapping is identical. Replace it, but indicate the 
>> backing PTEs
>> + *    could be kept.
>> + *
>> + *    ::
>> + *
>> + *         0     a     1
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *         0     a     1
>> + *    req: |-----------| (bo_offset=n)
>> + *
>> + *         0     a     1
>> + *    new: |-----------| (bo_offset=n)
>> + *
>> + *
>> + * 2) Requested mapping is identical, except for the BO offset, hence 
>> replace
>> + *    the mapping.
>> + *
>> + *    ::
>> + *
>> + *         0     a     1
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *         0     a     1
>> + *    req: |-----------| (bo_offset=m)
>> + *
>> + *         0     a     1
>> + *    new: |-----------| (bo_offset=m)
>> + *
>> + *
>> + * 3) Requested mapping is identical, except for the backing BO, 
>> hence replace
>> + *    the mapping.
>> + *
>> + *    ::
>> + *
>> + *         0     a     1
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *         0     b     1
>> + *    req: |-----------| (bo_offset=n)
>> + *
>> + *         0     b     1
>> + *    new: |-----------| (bo_offset=n)
>> + *
>> + *
>> + * 4) Existent mapping is a left aligned subset of the requested one, 
>> hence
>> + *    replace the existent one.
>> + *
>> + *    ::
>> + *
>> + *         0  a  1
>> + *    old: |-----|       (bo_offset=n)
>> + *
>> + *         0     a     2
>> + *    req: |-----------| (bo_offset=n)
>> + *
>> + *         0     a     2
>> + *    new: |-----------| (bo_offset=n)
>> + *
>> + *    .. note::
>> + *       We expect to see the same result for a request with a 
>> different BO
>> + *       and/or non-contiguous BO offset.
>> + *
>> + *
>> + * 5) Requested mapping's range is a left aligned subset of the 
>> existent one,
>> + *    but backed by a different BO. Hence, map the requested mapping 
>> and split
>> + *    the existent one adjusting it's BO offset.
> Typo: s/it's/its/ above and in multiple places below.
>> + *
>> + *    ::
>> + *
>> + *         0     a     2
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *         0  b  1
>> + *    req: |-----|       (bo_offset=n)
>> + *
>> + *         0  b  1  a' 2
>> + *    new: |-----|-----| (b.bo_offset=n, a.bo_offset=n+1)
>> + *
>> + *    .. note::
>> + *       We expect to see the same result for a request with a 
>> different BO
>> + *       and/or non-contiguous BO offset.
>> + *
>> + *
>> + * 6) Existent mapping is a superset of the requested mapping. Split 
>> it up, but
>> + *    indicate that the backing PTEs could be kept.
>> + *
>> + *    ::
>> + *
>> + *         0     a     2
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *         0  a  1
>> + *    req: |-----|       (bo_offset=n)
>> + *
>> + *         0  a  1  a' 2
>> + *    new: |-----|-----| (a.bo_offset=n, a'.bo_offset=n+1)
>> + *
>> + *
>> + * 7) Requested mapping's range is a right aligned subset of the 
>> existent one,
>> + *    but backed by a different BO. Hence, map the requested mapping 
>> and split
>> + *    the existent one, without adjusting the BO offset.
>> + *
>> + *    ::
>> + *
>> + *         0     a     2
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *               1  b  2
>> + *    req:       |-----| (bo_offset=m)
>> + *
>> + *         0  a  1  b  2
>> + *    new: |-----|-----| (a.bo_offset=n,b.bo_offset=m)
>> + *
>> + *
>> + * 8) Existent mapping is a superset of the requested mapping. Split 
>> it up, but
>> + *    indicate that the backing PTEs could be kept.
>> + *
>> + *    ::
>> + *
>> + *          0     a     2
>> + *    old: |-----------| (bo_offset=n)
>> + *
>> + *               1  a  2
>> + *    req:       |-----| (bo_offset=n+1)
>> + *
>> + *         0  a' 1  a  2
>> + *    new: |-----|-----| (a'.bo_offset=n, a.bo_offset=n+1)
>> + *
>> + *
>> + * 9) Existent mapping is overlapped at the end by the requested 
>> mapping backed
>> + *    by a different BO. Hence, map the requested mapping and split 
>> up the
>> + *    existent one, without adjusting the BO offset.
>> + *
>> + *    ::
>> + *
>> + *         0     a     2
>> + *    old: |-----------|       (bo_offset=n)
>> + *
>> + *               1     b     3
>> + *    req:       |-----------| (bo_offset=m)
>> + *
>> + *         0  a  1     b     3
>> + *    new: |-----|-----------| (a.bo_offset=n,b.bo_offset=m)
>> + *
>> + *
>> + * 10) Existent mapping is overlapped by the requested mapping, both 
>> having the
>> + *     same backing BO with a contiguous offset. Indicate the backing 
>> PTEs of
>> + *     the old mapping could be kept.
>> + *
>> + *     ::
>> + *
>> + *          0     a     2
>> + *     old: |-----------|       (bo_offset=n)
>> + *
>> + *                1     a     3
>> + *     req:       |-----------| (bo_offset=n+1)
>> + *
>> + *          0  a' 1     a     3
>> + *     new: |-----|-----------| (a'.bo_offset=n, a.bo_offset=n+1)
>> + *
>> + *
>> + * 11) Requested mapping's range is a centered subset of the existent 
>> one
>> + *     having a different backing BO. Hence, map the requested 
>> mapping and split
>> + *     up the existent one in two mappings, adjusting the BO offset 
>> of the right
>> + *     one accordingly.
>> + *
>> + *     ::
>> + *
>> + *          0        a        3
>> + *     old: |-----------------| (bo_offset=n)
>> + *
>> + *                1  b  2
>> + *     req:       |-----|       (bo_offset=m)
>> + *
>> + *          0  a  1  b  2  a' 3
>> + *     new: |-----|-----|-----| 
>> (a.bo_offset=n,b.bo_offset=m,a'.bo_offset=n+2)
>> + *
>> + *
>> + * 12) Requested mapping is a contiguous subset of the existent one. 
>> Split it
>> + *     up, but indicate that the backing PTEs could be kept.
>> + *
>> + *     ::
>> + *
>> + *          0        a        3
>> + *     old: |-----------------| (bo_offset=n)
>> + *
>> + *                1  a  2
>> + *     req:       |-----|       (bo_offset=n+1)
>> + *
>> + *          0  a' 1  a  2 a'' 3
>> + *     old: |-----|-----|-----| (a'.bo_offset=n, a.bo_offset=n+1, 
>> a''.bo_offset=n+2)
>> + *
>> + *
>> + * 13) Existent mapping is a right aligned subset of the requested 
>> one, hence
>> + *     replace the existent one.
>> + *
>> + *     ::
>> + *
>> + *                1  a  2
>> + *     old:       |-----| (bo_offset=n+1)
>> + *
>> + *          0     a     2
>> + *     req: |-----------| (bo_offset=n)
>> + *
>> + *          0     a     2
>> + *     new: |-----------| (bo_offset=n)
>> + *
>> + *     .. note::
>> + *        We expect to see the same result for a request with a 
>> different bo
>> + *        and/or non-contiguous bo_offset.
>> + *
>> + *
>> + * 14) Existent mapping is a centered subset of the requested one, hence
>> + *     replace the existent one.
>> + *
>> + *     ::
>> + *
>> + *                1  a  2
>> + *     old:       |-----| (bo_offset=n+1)
>> + *
>> + *          0        a       3
>> + *     req: |----------------| (bo_offset=n)
>> + *
>> + *          0        a       3
>> + *     new: |----------------| (bo_offset=n)
>> + *
>> + *     .. note::
>> + *        We expect to see the same result for a request with a 
>> different bo
>> + *        and/or non-contiguous bo_offset.
>> + *
>> + *
>> + * 15) Existent mappings is overlapped at the beginning by the 
>> requested mapping
>> + *     backed by a different BO. Hence, map the requested mapping and 
>> split up
>> + *     the existent one, adjusting it's BO offset accordingly.
>> + *
>> + *     ::
>> + *
>> + *                1     a     3
>> + *     old:       |-----------| (bo_offset=n)
>> + *
>> + *          0     b     2
>> + *     req: |-----------|       (bo_offset=m)
>> + *
>> + *          0     b     2  a' 3
>> + *     new: |-----------|-----| (b.bo_offset=m,a.bo_offset=n+2)
>> + */
>> +
>> +/**
>> + * DOC: Locking
>> + *
>> + * Generally, the GPU VA manager does not take care of locking 
>> itself, it is
>> + * the drivers responsibility to take care about locking. Drivers 
>> might want to
>> + * protect the following operations: inserting, removing and iterating
>> + * &drm_gpuva objects as well as generating all kinds of operations, 
>> such as
>> + * split / merge or prefetch.
>> + *
>> + * The GPU VA manager also does not take care of the locking of the 
>> backing
>> + * &drm_gem_object buffers GPU VA lists by itself; drivers are 
>> responsible to
>> + * enforce mutual exclusion using either the GEMs dma_resv lock or 
>> alternatively
>> + * a driver specific external lock by setting the 
>> @DRM_GPUVA_MANAGER_LOCK_EXTERN
>> + * flag.
> 
> Is the external lock used or anticipated by any WIP implementation? If 
> not I suggest to leave it out until there is a user.

I think the PowerVR driver requires this. However, it's generally useful 
for any driver using direct callbacks rather than drm_gpuva_ops.

Once the page table handling in Nouveau is re-worked, and direct 
callbacks can be used, I probably want to use this in Nouveau as well.

Gonna fix up all other comments.

- Danilo

> 
>> + *
>> + * For the latter, functions such as drm_gpuva_link() or 
>> drm_gpuva_unlink()
>> + * contain lockdep checks to indicate locking issues. For this to 
>> work drivers
>> + * must provide (in case the @DRM_GPUVA_MANAGER_LOCK_EXTERN flag is 
>> set) their
>> + * external lock with drm_gpuva_manager_set_ext_lock() after 
>> initialization.
>> + */
>> +
>> +/**
>> + * DOC: Examples
>> + *
>> + * This section gives two examples on how to let the DRM GPUVA 
>> Manager generate
>> + * &drm_gpuva_op in order to satisfy a given map or unmap request and 
>> how to
>> + * make use of them.
>> + *
>> + * The below code is strictly limited to illustrate the generic usage 
>> pattern.
>> + * To maintain simplicitly, it doesn't make use of any abstractions 
>> for common
>> + * code, different (asyncronous) stages with fence signalling 
>> critical paths,
>> + * any other helpers or error handling in terms of freeing memory and 
>> dropping
>> + * previously taken locks.
>> + *
>> + * 1) Obtain a list of &drm_gpuva_op to create a new mapping::
>> + *
>> + *    // Allocates a new &drm_gpuva.
>> + *    struct drm_gpuva * driver_gpuva_alloc(void);
>> + *
>> + *    // Typically drivers would embedd the &drm_gpuva_manager and 
>> &drm_gpuva
>> + *    // structure in individual driver structures and lock the 
>> dma-resv with
>> + *    // drm_exec or similar helpers.
>> + *    int driver_mapping_create(struct drm_gpuva_manager *mgr,
>> + *                  u64 addr, u64 range,
>> + *                  struct drm_gem_object *obj, u64 offset)
>> + *    {
>> + *        struct drm_gpuva_ops *ops;
>> + *        struct drm_gpuva_op *op
>> + *
>> + *        driver_lock_va_space();
>> + *        ops = drm_gpuva_sm_map_ops_create(mgr, addr, range,
>> + *                          obj, offset);
>> + *        if (IS_ERR(ops))
>> + *            return PTR_ERR(ops);
>> + *
>> + *        drm_gpuva_for_each_op(op, ops) {
>> + *            struct drm_gpuva *va;
>> + *
>> + *            switch (op->op) {
>> + *            case DRM_GPUVA_OP_MAP:
>> + *                va = driver_gpuva_alloc();
>> + *                if (!va)
>> + *                    ; // unwind previous VA space updates,
>> + *                      // free memory and unlock
>> + *
>> + *                driver_vm_map();
>> + *                drm_gpuva_map(mgr, va, &op->map);
>> + *                drm_gpuva_link(va);
>> + *
>> + *                break;
>> + *            case DRM_GPUVA_OP_REMAP: {
>> + *                struct drm_gpuva *prev = NULL, *next = NULL;
>> + *
>> + *                va = op->remap.unmap->va;
>> + *
>> + *                if (op->remap.prev) {
>> + *                    prev = driver_gpuva_alloc();
>> + *                    if (!prev)
>> + *                        ; // unwind previous VA space
>> + *                          // updates, free memory and
>> + *                          // unlock
>> + *                }
>> + *
>> + *                if (op->remap.next) {
>> + *                    next = driver_gpuva_alloc();
>> + *                    if (!next)
>> + *                        ; // unwind previous VA space
>> + *                          // updates, free memory and
>> + *                          // unlock
>> + *                }
>> + *
>> + *                driver_vm_remap();
>> + *                drm_gpuva_remap(prev, next, &op->remap);
>> + *
>> + *                drm_gpuva_unlink(va);
>> + *                if (prev)
>> + *                    drm_gpuva_link(prev);
>> + *                if (next)
>> + *                    drm_gpuva_link(next);
>> + *
>> + *                break;
>> + *            }
>> + *            case DRM_GPUVA_OP_UNMAP:
>> + *                va = op->unmap->va;
>> + *
>> + *                driver_vm_unmap();
>> + *                drm_gpuva_unlink(va);
>> + *                drm_gpuva_unmap(&op->unmap);
>> + *
>> + *                break;
>> + *            default:
>> + *                break;
>> + *            }
>> + *        }
>> + *        driver_unlock_va_space();
>> + *
>> + *        return 0;
>> + *    }
>> + *
>> + * 2) Receive a callback for each &drm_gpuva_op to create a new 
>> mapping::
>> + *
>> + *    struct driver_context {
>> + *        struct drm_gpuva_manager *mgr;
>> + *        struct drm_gpuva *new_va;
>> + *        struct drm_gpuva *prev_va;
>> + *        struct drm_gpuva *next_va;
>> + *    };
>> + *
>> + *    // ops to pass to drm_gpuva_manager_init()
>> + *    static const struct drm_gpuva_fn_ops driver_gpuva_ops = {
>> + *        .sm_step_map = driver_gpuva_map,
>> + *        .sm_step_remap = driver_gpuva_remap,
>> + *        .sm_step_unmap = driver_gpuva_unmap,
>> + *    };
>> + *
>> + *    // Typically drivers would embedd the &drm_gpuva_manager and 
>> &drm_gpuva
>> + *    // structure in individual driver structures and lock the 
>> dma-resv with
>> + *    // drm_exec or similar helpers.
>> + *    int driver_mapping_create(struct drm_gpuva_manager *mgr,
>> + *                  u64 addr, u64 range,
>> + *                  struct drm_gem_object *obj, u64 offset)
>> + *    {
>> + *        struct driver_context ctx;
>> + *        struct drm_gpuva_ops *ops;
>> + *        struct drm_gpuva_op *op;
>> + *        int ret = 0;
>> + *
>> + *        ctx.mgr = mgr;
>> + *
>> + *        ctx.new_va = kzalloc(sizeof(*ctx.new_va), GFP_KERNEL);
>> + *        ctx.prev_va = kzalloc(sizeof(*ctx.prev_va), GFP_KERNEL);
>> + *        ctx.next_va = kzalloc(sizeof(*ctx.next_va), GFP_KERNEL);
>> + *        if (!ctx.new_va || !ctx.prev_va || !ctx.next_va) {
>> + *            ret = -ENOMEM;
>> + *            goto out;
>> + *        }
>> + *
>> + *        driver_lock_va_space();
>> + *        ret = drm_gpuva_sm_map(mgr, &ctx, addr, range, obj, offset);
>> + *        driver_unlock_va_space();
>> + *
>> + *    out:
>> + *        kfree(ctx.new_va);
>> + *        kfree(ctx.prev_va);
>> + *        kfree(ctx.next_va);
>> + *        return ret;
>> + *    }
>> + *
>> + *    int driver_gpuva_map(struct drm_gpuva_op *op, void *__ctx)
>> + *    {
>> + *        struct driver_context *ctx = __ctx;
>> + *
>> + *        drm_gpuva_map(ctx->mgr, ctx->new_va, &op->map);
>> + *
>> + *        drm_gpuva_link(ctx->new_va);
>> + *
>> + *        // prevent the new GPUVA from being freed in
>> + *        // driver_mapping_create()
>> + *        ctx->new_va = NULL;
>> + *
>> + *        return 0;
>> + *    }
>> + *
>> + *    int driver_gpuva_remap(struct drm_gpuva_op *op, void *__ctx)
>> + *    {
>> + *        struct driver_context *ctx = __ctx;
>> + *
>> + *        drm_gpuva_remap(ctx->prev_va, ctx->next_va, &op->remap);
>> + *
>> + *        drm_gpuva_unlink(op->remap.unmap->va);
>> + *        kfree(op->remap.unmap->va);
>> + *
>> + *        if (op->remap.prev) {
>> + *            drm_gpuva_link(ctx->prev_va);
>> + *            ctx->prev_va = NULL;
>> + *        }
>> + *
>> + *        if (op->remap.next) {
>> + *            drm_gpuva_link(ctx->next_va);
>> + *            ctx->next_va = NULL;
>> + *        }
>> + *
>> + *        return 0;
>> + *    }
>> + *
>> + *    int driver_gpuva_unmap(struct drm_gpuva_op *op, void *__ctx)
>> + *    {
>> + *        drm_gpuva_unlink(op->unmap.va);
>> + *        drm_gpuva_unmap(&op->unmap);
>> + *        kfree(op->unmap.va);
>> + *
>> + *        return 0;
>> + *    }
>> + */
>> +
>> +#define to_drm_gpuva(__node)    container_of((__node), struct 
>> drm_gpuva, rb.node)
>> +
>> +#define GPUVA_START(node) ((node)->va.addr)
>> +#define GPUVA_LAST(node) ((node)->va.addr + (node)->va.range - 1)
>> +
>> +/* We do not actually use drm_gpuva_it_next(), tell the compiler to 
>> not complain
>> + * about this.
>> + */
>> +INTERVAL_TREE_DEFINE(struct drm_gpuva, rb.node, u64, rb.__subtree_last,
>> +             GPUVA_START, GPUVA_LAST, static __attribute__((unused)),
> 
> Would  s/__attribute__((unused))/__maybe_unused/ work here?
> 
>> +             drm_gpuva_it)
>> +
>> +static int __drm_gpuva_insert(struct drm_gpuva_manager *mgr,
>> +                  struct drm_gpuva *va);
>> +static void __drm_gpuva_remove(struct drm_gpuva *va);
>> +
>> +static inline bool
> "static inline" is typically used only in header files, since the 
> compiler should be smart enough to inline if beneficial. Prefer 
> "static". Also in multiple places below.
>> +drm_gpuva_check_overflow(u64 addr, u64 range)
>> +{
>> +    u64 end;
>> +
>> +    return WARN(check_add_overflow(addr, range, &end),
>> +            "GPUVA address limited to %lu bytes.\n", sizeof(end));
>> +}
>> +
>> +static inline bool
>> +drm_gpuva_in_mm_range(struct drm_gpuva_manager *mgr, u64 addr, u64 
>> range)
>> +{
>> +    u64 end = addr + range;
>> +    u64 mm_start = mgr->mm_start;
>> +    u64 mm_end = mm_start + mgr->mm_range;
>> +
>> +    return addr >= mm_start && end <= mm_end;
>> +}
>> +
>> +static inline bool
>> +drm_gpuva_in_kernel_node(struct drm_gpuva_manager *mgr, u64 addr, u64 
>> range)
>> +{
>> +    u64 end = addr + range;
>> +    u64 kstart = mgr->kernel_alloc_node.va.addr;
>> +    u64 krange = mgr->kernel_alloc_node.va.range;
>> +    u64 kend = kstart + krange;
>> +
>> +    return krange && addr < kend && kstart < end;
>> +}
>> +
>> +static inline bool
>> +drm_gpuva_range_valid(struct drm_gpuva_manager *mgr,
>> +              u64 addr, u64 range)
>> +{
>> +
>> +    return !drm_gpuva_check_overflow(addr, range) &&
>> +           drm_gpuva_in_mm_range(mgr, addr, range) &&
>> +           !drm_gpuva_in_kernel_node(mgr, addr, range);
>> +}
>> +
>> +/**
>> + * drm_gpuva_manager_init - initialize a &drm_gpuva_manager
> Function kerneldoc names should end with "()": drm_gpuva_manager_init(). 
> General comment across the patch.
>> + * @mgr: pointer to the &drm_gpuva_manager to initialize
>> + * @name: the name of the GPU VA space
>> + * @start_offset: the start offset of the GPU VA space
>> + * @range: the size of the GPU VA space
>> + * @reserve_offset: the start of the kernel reserved GPU VA area
>> + * @reserve_range: the size of the kernel reserved GPU VA area
>> + * @ops: &drm_gpuva_fn_ops called on &drm_gpuva_sm_map / 
>> &drm_gpuva_sm_unmap
>> + * @flags: the feature flags for the &drm_gpuva_manager
>> + *
>> + * The &drm_gpuva_manager must be initialized with this function 
>> before use.
>> + *
>> + * Note that @mgr must be cleared to 0 before calling this function. 
>> The given
>> + * &name is expected to be managed by the surrounding driver structures.
>> + */
>> +void
>> +drm_gpuva_manager_init(struct drm_gpuva_manager *mgr,
>> +               const char *name,
>> +               u64 start_offset, u64 range,
>> +               u64 reserve_offset, u64 reserve_range,
>> +               const struct drm_gpuva_fn_ops *ops,
>> +               enum drm_gpuva_manager_flags flags)
>> +{
>> +    mgr->rb.tree = RB_ROOT_CACHED;
>> +    INIT_LIST_HEAD(&mgr->rb.list);
>> +
>> +    drm_gpuva_check_overflow(start_offset, range);
>> +    mgr->mm_start = start_offset;
>> +    mgr->mm_range = range;
>> +
>> +    mgr->name = name ? name : "unknown";
>> +    mgr->flags = flags;
>> +    mgr->ops = ops;
>> +
>> +    memset(&mgr->kernel_alloc_node, 0, sizeof(struct drm_gpuva));
>> +
>> +    if (reserve_range) {
>> +        mgr->kernel_alloc_node.va.addr = reserve_offset;
>> +        mgr->kernel_alloc_node.va.range = reserve_range;
>> +
>> +        if (likely(!drm_gpuva_check_overflow(reserve_offset,
>> +                             reserve_range)))
>> +            __drm_gpuva_insert(mgr, &mgr->kernel_alloc_node);
>> +    }
>> +
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_manager_init);
>> +
>> +/**
>> + * drm_gpuva_manager_destroy - cleanup a &drm_gpuva_manager
>> + * @mgr: pointer to the &drm_gpuva_manager to clean up
>> + *
>> + * Note that it is a bug to call this function on a manager that still
>> + * holds GPU VA mappings.
>> + */
>> +void
>> +drm_gpuva_manager_destroy(struct drm_gpuva_manager *mgr)
>> +{
>> +    mgr->name = NULL;
>> +
>> +    if (mgr->kernel_alloc_node.va.range)
>> +        __drm_gpuva_remove(&mgr->kernel_alloc_node);
>> +
>> +    WARN(!RB_EMPTY_ROOT(&mgr->rb.tree.rb_root),
>> +         "GPUVA tree is not empty, potentially leaking memory.");
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_manager_destroy);
>> +
>> +static int
>> +__drm_gpuva_insert(struct drm_gpuva_manager *mgr,
>> +           struct drm_gpuva *va)
>> +{
>> +    struct rb_node *node;
>> +    struct list_head *head;
>> +
>> +    if (drm_gpuva_it_iter_first(&mgr->rb.tree,
>> +                    GPUVA_START(va),
>> +                    GPUVA_LAST(va)))
>> +        return -EEXIST;
>> +
>> +    va->mgr = mgr;
>> +
>> +    drm_gpuva_it_insert(va, &mgr->rb.tree);
>> +
>> +    node = rb_prev(&va->rb.node);
>> +    if (node)
>> +        head = &(to_drm_gpuva(node))->rb.entry;
>> +    else
>> +        head = &mgr->rb.list;
>> +
>> +    list_add(&va->rb.entry, head);
>> +
>> +    return 0;
>> +}
>> +
>> +/**
>> + * drm_gpuva_insert - insert a &drm_gpuva
>> + * @mgr: the &drm_gpuva_manager to insert the &drm_gpuva in
>> + * @va: the &drm_gpuva to insert
>> + *
>> + * Insert a &drm_gpuva with a given address and range into a
>> + * &drm_gpuva_manager.
>> + *
>> + * It is safe to use this function using the safe versions of 
>> iterating the GPU
>> + * VA space, such as drm_gpuva_for_each_va_safe() and
>> + * drm_gpuva_for_each_va_range_safe().
>> + *
>> + * Returns: 0 on success, negative error code on failure.
>> + */
>> +int
>> +drm_gpuva_insert(struct drm_gpuva_manager *mgr,
>> +         struct drm_gpuva *va)
>> +{
>> +    u64 addr = va->va.addr;
>> +    u64 range = va->va.range;
>> +
>> +    if (unlikely(!drm_gpuva_range_valid(mgr, addr, range)))
>> +        return -EINVAL;
>> +
>> +    return __drm_gpuva_insert(mgr, va);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_insert);
>> +
>> +static void
>> +__drm_gpuva_remove(struct drm_gpuva *va)
>> +{
>> +    drm_gpuva_it_remove(va, &va->mgr->rb.tree);
>> +    list_del_init(&va->rb.entry);
>> +}
>> +
>> +/**
>> + * drm_gpuva_remove - remove a &drm_gpuva
>> + * @va: the &drm_gpuva to remove
>> + *
>> + * This removes the given &va from the underlaying tree.
>> + *
>> + * It is safe to use this function using the safe versions of 
>> iterating the GPU
>> + * VA space, such as drm_gpuva_for_each_va_safe() and
>> + * drm_gpuva_for_each_va_range_safe().
>> + */
>> +void
>> +drm_gpuva_remove(struct drm_gpuva *va)
>> +{
>> +    struct drm_gpuva_manager *mgr = va->mgr;
>> +
>> +    if (unlikely(va == &mgr->kernel_alloc_node)) {
>> +        WARN(1, "Can't destroy kernel reserved node.\n");
>> +        return;
>> +    }
>> +
>> +    __drm_gpuva_remove(va);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_remove);
>> +
>> +/**
>> + * drm_gpuva_link - link a &drm_gpuva
>> + * @va: the &drm_gpuva to link
>> + *
>> + * This adds the given &va to the GPU VA list of the &drm_gem_object 
>> it is
>> + * associated with.
>> + *
>> + * This function expects the caller to protect the GEM's GPUVA list 
>> against
>> + * concurrent access using the GEMs dma_resv lock.
>> + */
>> +void
>> +drm_gpuva_link(struct drm_gpuva *va)
>> +{
>> +    struct drm_gpuva_manager *mgr = va->mgr;
>> +    struct drm_gem_object *obj = va->gem.obj;
>> +
>> +    if (unlikely(!obj))
>> +        return;
>> +
>> +    if (drm_gpuva_manager_external_lock(mgr))
>> +        drm_gpuva_manager_ext_assert_held(mgr);
>> +    else
>> +        dma_resv_assert_held(obj->resv);
>> +
>> +    list_add_tail(&va->gem.entry, &obj->gpuva.list);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_link);
>> +
>> +/**
>> + * drm_gpuva_unlink - unlink a &drm_gpuva
>> + * @va: the &drm_gpuva to unlink
>> + *
>> + * This removes the given &va from the GPU VA list of the 
>> &drm_gem_object it is
>> + * associated with.
>> + *
>> + * This function expects the caller to protect the GEM's GPUVA list 
>> against
>> + * concurrent access using the GEMs dma_resv lock.
>> + */
>> +void
>> +drm_gpuva_unlink(struct drm_gpuva *va)
>> +{
>> +    struct drm_gpuva_manager *mgr = va->mgr;
>> +    struct drm_gem_object *obj = va->gem.obj;
>> +
>> +    if (unlikely(!obj))
>> +        return;
>> +
>> +    if (drm_gpuva_manager_external_lock(mgr))
>> +        drm_gpuva_manager_ext_assert_held(mgr);
>> +    else
>> +        dma_resv_assert_held(obj->resv);
>> +
>> +    list_del_init(&va->gem.entry);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_unlink);
>> +
>> +/**
>> + * drm_gpuva_find_first - find the first &drm_gpuva in the given range
>> + * @mgr: the &drm_gpuva_manager to search in
>> + * @addr: the &drm_gpuvas address
>> + * @range: the &drm_gpuvas range
>> + *
>> + * Returns: the first &drm_gpuva within the given range
>> + */
>> +struct drm_gpuva *
>> +drm_gpuva_find_first(struct drm_gpuva_manager *mgr,
>> +             u64 addr, u64 range)
>> +{
>> +    u64 last = addr + range - 1;
>> +
>> +    return drm_gpuva_it_iter_first(&mgr->rb.tree, addr, last);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_find_first);
>> +
>> +/**
>> + * drm_gpuva_find - find a &drm_gpuva
>> + * @mgr: the &drm_gpuva_manager to search in
>> + * @addr: the &drm_gpuvas address
>> + * @range: the &drm_gpuvas range
>> + *
>> + * Returns: the &drm_gpuva at a given &addr and with a given &range
>> + */
>> +struct drm_gpuva *
>> +drm_gpuva_find(struct drm_gpuva_manager *mgr,
>> +           u64 addr, u64 range)
>> +{
>> +    struct drm_gpuva *va;
>> +
>> +    va = drm_gpuva_find_first(mgr, addr, range);
>> +    if (!va)
>> +        goto out;
>> +
>> +    if (va->va.addr != addr ||
>> +        va->va.range != range)
>> +        goto out;
>> +
>> +    return va;
>> +
>> +out:
>> +    return NULL;
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_find);
>> +
>> +/**
>> + * drm_gpuva_find_prev - find the &drm_gpuva before the given address
>> + * @mgr: the &drm_gpuva_manager to search in
>> + * @start: the given GPU VA's start address
>> + *
>> + * Find the adjacent &drm_gpuva before the GPU VA with given &start 
>> address.
>> + *
>> + * Note that if there is any free space between the GPU VA mappings 
>> no mapping
>> + * is returned.
>> + *
>> + * Returns: a pointer to the found &drm_gpuva or NULL if none was found
>> + */
>> +struct drm_gpuva *
>> +drm_gpuva_find_prev(struct drm_gpuva_manager *mgr, u64 start)
>> +{
>> +    if (!drm_gpuva_range_valid(mgr, start - 1, 1))
>> +        return NULL;
>> +
>> +    return drm_gpuva_it_iter_first(&mgr->rb.tree, start - 1, start);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_find_prev);
>> +
>> +/**
>> + * drm_gpuva_find_next - find the &drm_gpuva after the given address
>> + * @mgr: the &drm_gpuva_manager to search in
>> + * @end: the given GPU VA's end address
>> + *
>> + * Find the adjacent &drm_gpuva after the GPU VA with given &end 
>> address.
>> + *
>> + * Note that if there is any free space between the GPU VA mappings 
>> no mapping
>> + * is returned.
>> + *
>> + * Returns: a pointer to the found &drm_gpuva or NULL if none was found
>> + */
>> +struct drm_gpuva *
>> +drm_gpuva_find_next(struct drm_gpuva_manager *mgr, u64 end)
>> +{
>> +    if (!drm_gpuva_range_valid(mgr, end, 1))
>> +        return NULL;
>> +
>> +    return drm_gpuva_it_iter_first(&mgr->rb.tree, end, end + 1);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_find_next);
>> +
>> +/**
>> + * drm_gpuva_interval_empty - indicate whether a given interval of 
>> the VA space
>> + * is empty
>> + * @mgr: the &drm_gpuva_manager to check the range for
>> + * @addr: the start address of the range
>> + * @range: the range of the interval
>> + *
>> + * Returns: true if the interval is empty, false otherwise
>> + */
>> +bool
>> +drm_gpuva_interval_empty(struct drm_gpuva_manager *mgr, u64 addr, u64 
>> range)
>> +{
>> +    return !drm_gpuva_find_first(mgr, addr, range);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_interval_empty);
>> +
>> +/**
>> + * drm_gpuva_map - helper to insert a &drm_gpuva according to a
>> + * &drm_gpuva_op_map
>> + * @mgr: the &drm_gpuva_manager
>> + * @va: the &drm_gpuva to insert
>> + * @op: the &drm_gpuva_op_map to initialize @va with
>> + *
>> + * Initializes the @va from the @op and inserts it into the given @mgr.
>> + */
>> +void
>> +drm_gpuva_map(struct drm_gpuva_manager *mgr,
>> +          struct drm_gpuva *va,
>> +          struct drm_gpuva_op_map *op)
>> +{
>> +    drm_gpuva_init_from_op(va, op);
>> +    drm_gpuva_insert(mgr, va);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_map);
>> +
>> +/**
>> + * drm_gpuva_remap - helper to remap a &drm_gpuva according to a
>> + * &drm_gpuva_op_remap
>> + * @prev: the &drm_gpuva to remap when keeping the start of a mapping
>> + * @next: the &drm_gpuva to remap when keeping the end of a mapping
>> + * @op: the &drm_gpuva_op_remap to initialize @prev and @next with
>> + *
>> + * Removes the currently mapped &drm_gpuva and remaps it using @prev 
>> and/or
>> + * @next.
>> + */
>> +void
>> +drm_gpuva_remap(struct drm_gpuva *prev,
>> +        struct drm_gpuva *next,
>> +        struct drm_gpuva_op_remap *op)
>> +{
>> +    struct drm_gpuva *curr = op->unmap->va;
>> +    struct drm_gpuva_manager *mgr = curr->mgr;
>> +    struct drm_gpuva_op_map *map;
>> +
>> +    drm_gpuva_remove(curr);
>> +
>> +    if ((map = op->prev)) {
>> +        drm_gpuva_init_from_op(prev, map);
>> +        drm_gpuva_insert(mgr, prev);
>> +    }
>> +
>> +    if ((map = op->next)) {
>> +        drm_gpuva_init_from_op(next, map);
>> +        drm_gpuva_insert(mgr, next);
>> +    }
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_remap);
>> +
>> +/**
>> + * drm_gpuva_unmap - helper to remove a &drm_gpuva according to a
>> + * &drm_gpuva_op_unmap
>> + * @op: the &drm_gpuva_op_unmap specifying the &drm_gpuva to remove
>> + *
>> + * Removes the &drm_gpuva associated with the &drm_gpuva_op_unmap.
>> + */
>> +void
>> +drm_gpuva_unmap(struct drm_gpuva_op_unmap *op)
>> +{
>> +    drm_gpuva_remove(op->va);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_unmap);
>> +
>> +static int
>> +op_map_cb(const struct drm_gpuva_fn_ops *fn, void *priv,
>> +      u64 addr, u64 range,
>> +      struct drm_gem_object *obj, u64 offset)
>> +{
>> +    struct drm_gpuva_op op = {};
>> +
>> +    op.op = DRM_GPUVA_OP_MAP;
>> +    op.map.va.addr = addr;
>> +    op.map.va.range = range;
>> +    op.map.gem.obj = obj;
>> +    op.map.gem.offset = offset;
>> +
>> +    return fn->sm_step_map(&op, priv);
>> +}
>> +
>> +static int
>> +op_remap_cb(const struct drm_gpuva_fn_ops *fn, void *priv,
>> +        struct drm_gpuva_op_map *prev,
>> +        struct drm_gpuva_op_map *next,
>> +        struct drm_gpuva_op_unmap *unmap)
>> +{
>> +    struct drm_gpuva_op op = {};
>> +    struct drm_gpuva_op_remap *r;
>> +
>> +    op.op = DRM_GPUVA_OP_REMAP;
>> +    r = &op.remap;
>> +    r->prev = prev;
>> +    r->next = next;
>> +    r->unmap = unmap;
>> +
>> +    return fn->sm_step_remap(&op, priv);
>> +}
>> +
>> +static int
>> +op_unmap_cb(const struct drm_gpuva_fn_ops *fn, void *priv,
>> +        struct drm_gpuva *va, bool merge)
>> +{
>> +    struct drm_gpuva_op op = {};
>> +
>> +    op.op = DRM_GPUVA_OP_UNMAP;
>> +    op.unmap.va = va;
>> +    op.unmap.keep = merge;
>> +
>> +    return fn->sm_step_unmap(&op, priv);
>> +}
>> +
>> +static int
>> +__drm_gpuva_sm_map(struct drm_gpuva_manager *mgr,
>> +           const struct drm_gpuva_fn_ops *ops, void *priv,
>> +           u64 req_addr, u64 req_range,
>> +           struct drm_gem_object *req_obj, u64 req_offset)
>> +{
>> +    struct drm_gpuva *va, *next, *prev = NULL;
>> +    u64 req_end = req_addr + req_range;
>> +    int ret;
>> +
>> +    if (unlikely(!drm_gpuva_range_valid(mgr, req_addr, req_range)))
>> +        return -EINVAL;
>> +
>> +    drm_gpuva_for_each_va_range_safe(va, next, mgr, req_addr, req_end) {
>> +        struct drm_gem_object *obj = va->gem.obj;
>> +        u64 offset = va->gem.offset;
>> +        u64 addr = va->va.addr;
>> +        u64 range = va->va.range;
>> +        u64 end = addr + range;
>> +        bool merge = !!va->gem.obj;
>> +
>> +        if (addr == req_addr) {
>> +            merge &= obj == req_obj &&
>> +                 offset == req_offset;
>> +
>> +            if (end == req_end) {
>> +                ret = op_unmap_cb(ops, priv, va, merge);
>> +                if (ret)
>> +                    return ret;
>> +                break;
>> +            }
>> +
>> +            if (end < req_end) {
>> +                ret = op_unmap_cb(ops, priv, va, merge);
>> +                if (ret)
>> +                    return ret;
>> +                goto next;
>> +            }
>> +
>> +            if (end > req_end) {
>> +                struct drm_gpuva_op_map n = {
>> +                    .va.addr = req_end,
>> +                    .va.range = range - req_range,
>> +                    .gem.obj = obj,
>> +                    .gem.offset = offset + req_range,
>> +                };
>> +                struct drm_gpuva_op_unmap u = {
>> +                    .va = va,
>> +                    .keep = merge,
>> +                };
>> +
>> +                ret = op_remap_cb(ops, priv, NULL, &n, &u);
>> +                if (ret)
>> +                    return ret;
>> +                break;
>> +            }
>> +        } else if (addr < req_addr) {
>> +            u64 ls_range = req_addr - addr;
>> +            struct drm_gpuva_op_map p = {
>> +                .va.addr = addr,
>> +                .va.range = ls_range,
>> +                .gem.obj = obj,
>> +                .gem.offset = offset,
>> +            };
>> +            struct drm_gpuva_op_unmap u = { .va = va };
>> +
>> +            merge &= obj == req_obj &&
>> +                 offset + ls_range == req_offset;
>> +            u.keep = merge;
>> +
>> +            if (end == req_end) {
>> +                ret = op_remap_cb(ops, priv, &p, NULL, &u);
>> +                if (ret)
>> +                    return ret;
>> +                break;
>> +            }
>> +
>> +            if (end < req_end) {
>> +                ret = op_remap_cb(ops, priv, &p, NULL, &u);
>> +                if (ret)
>> +                    return ret;
>> +                goto next;
>> +            }
>> +
>> +            if (end > req_end) {
>> +                struct drm_gpuva_op_map n = {
>> +                    .va.addr = req_end,
>> +                    .va.range = end - req_end,
>> +                    .gem.obj = obj,
>> +                    .gem.offset = offset + ls_range +
>> +                              req_range,
>> +                };
>> +
>> +                ret = op_remap_cb(ops, priv, &p, &n, &u);
>> +                if (ret)
>> +                    return ret;
>> +                break;
>> +            }
>> +        } else if (addr > req_addr) {
>> +            merge &= obj == req_obj &&
>> +                 offset == req_offset +
>> +                       (addr - req_addr);
>> +
>> +            if (end == req_end) {
>> +                ret = op_unmap_cb(ops, priv, va, merge);
>> +                if (ret)
>> +                    return ret;
>> +                break;
>> +            }
>> +
>> +            if (end < req_end) {
>> +                ret = op_unmap_cb(ops, priv, va, merge);
>> +                if (ret)
>> +                    return ret;
>> +                goto next;
>> +            }
>> +
>> +            if (end > req_end) {
>> +                struct drm_gpuva_op_map n = {
>> +                    .va.addr = req_end,
>> +                    .va.range = end - req_end,
>> +                    .gem.obj = obj,
>> +                    .gem.offset = offset + req_end - addr,
>> +                };
>> +                struct drm_gpuva_op_unmap u = {
>> +                    .va = va,
>> +                    .keep = merge,
>> +                };
>> +
>> +                ret = op_remap_cb(ops, priv, NULL, &n, &u);
>> +                if (ret)
>> +                    return ret;
>> +                break;
>> +            }
>> +        }
>> +next:
>> +        prev = va;
>> +    }
>> +
>> +    return op_map_cb(ops, priv,
>> +             req_addr, req_range,
>> +             req_obj, req_offset);
>> +}
>> +
>> +static int
>> +__drm_gpuva_sm_unmap(struct drm_gpuva_manager *mgr,
>> +             const struct drm_gpuva_fn_ops *ops, void *priv,
>> +             u64 req_addr, u64 req_range)
>> +{
>> +    struct drm_gpuva *va, *next;
>> +    u64 req_end = req_addr + req_range;
>> +    int ret;
>> +
>> +    if (unlikely(!drm_gpuva_range_valid(mgr, req_addr, req_range)))
>> +        return -EINVAL;
>> +
>> +    drm_gpuva_for_each_va_range_safe(va, next, mgr, req_addr, req_end) {
>> +        struct drm_gpuva_op_map prev = {}, next = {};
>> +        bool prev_split = false, next_split = false;
>> +        struct drm_gem_object *obj = va->gem.obj;
>> +        u64 offset = va->gem.offset;
>> +        u64 addr = va->va.addr;
>> +        u64 range = va->va.range;
>> +        u64 end = addr + range;
>> +
>> +        if (addr < req_addr) {
>> +            prev.va.addr = addr;
>> +            prev.va.range = req_addr - addr;
>> +            prev.gem.obj = obj;
>> +            prev.gem.offset = offset;
>> +
>> +            prev_split = true;
>> +        }
>> +
>> +        if (end > req_end) {
>> +            next.va.addr = req_end;
>> +            next.va.range = end - req_end;
>> +            next.gem.obj = obj;
>> +            next.gem.offset = offset + (req_end - addr);
>> +
>> +            next_split = true;
>> +        }
>> +
>> +        if (prev_split || next_split) {
>> +            struct drm_gpuva_op_unmap unmap = { .va = va };
>> +
>> +            ret = op_remap_cb(ops, priv,
>> +                      prev_split ? &prev : NULL,
>> +                      next_split ? &next : NULL,
>> +                      &unmap);
>> +            if (ret)
>> +                return ret;
>> +        } else {
>> +            ret = op_unmap_cb(ops, priv, va, false);
>> +            if (ret)
>> +                return ret;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +/**
>> + * drm_gpuva_sm_map - creates the &drm_gpuva_op split/merge steps
>> + * @mgr: the &drm_gpuva_manager representing the GPU VA space
>> + * @req_addr: the start address of the new mapping
>> + * @req_range: the range of the new mapping
>> + * @req_obj: the &drm_gem_object to map
>> + * @req_offset: the offset within the &drm_gem_object
>> + * @priv: pointer to a driver private data structure
>> + *
>> + * This function iterates the given range of the GPU VA space. It 
>> utilizes the
>> + * &drm_gpuva_fn_ops to call back into the driver providing the split 
>> and merge
>> + * steps.
>> + *
>> + * Drivers may use these callbacks to update the GPU VA space right 
>> away within
>> + * the callback. In case the driver decides to copy and store the 
>> operations for
>> + * later processing neither this function nor &drm_gpuva_sm_unmap is 
>> allowed to
>> + * be called before the &drm_gpuva_manager's view of the GPU VA space 
>> was
>> + * updated with the previous set of operations. To update the
>> + * &drm_gpuva_manager's view of the GPU VA space drm_gpuva_insert(),
>> + * drm_gpuva_destroy_locked() and/or drm_gpuva_destroy_unlocked() 
>> should be
>> + * used.
>> + *
>> + * A sequence of callbacks can contain map, unmap and remap 
>> operations, but
>> + * the sequence of callbacks might also be empty if no operation is 
>> required,
>> + * e.g. if the requested mapping already exists in the exact same way.
>> + *
>> + * There can be an arbitrary amount of unmap operations, a maximum of 
>> two remap
>> + * operations and a single map operation. The latter one represents 
>> the original
>> + * map operation requested by the caller.
>> + *
>> + * Returns: 0 on success or a negative error code
>> + */
>> +int
>> +drm_gpuva_sm_map(struct drm_gpuva_manager *mgr, void *priv,
>> +         u64 req_addr, u64 req_range,
>> +         struct drm_gem_object *req_obj, u64 req_offset)
>> +{
>> +    const struct drm_gpuva_fn_ops *ops = mgr->ops;
>> +
>> +    if (unlikely(!(ops && ops->sm_step_map &&
>> +               ops->sm_step_remap &&
>> +               ops->sm_step_unmap)))
>> +        return -EINVAL;
>> +
>> +    return __drm_gpuva_sm_map(mgr, ops, priv,
>> +                  req_addr, req_range,
>> +                  req_obj, req_offset);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_sm_map);
>> +
>> +/**
>> + * drm_gpuva_sm_unmap - creates the &drm_gpuva_ops to split on unmap
>> + * @mgr: the &drm_gpuva_manager representing the GPU VA space
>> + * @priv: pointer to a driver private data structure
>> + * @req_addr: the start address of the range to unmap
>> + * @req_range: the range of the mappings to unmap
>> + *
>> + * This function iterates the given range of the GPU VA space. It 
>> utilizes the
>> + * &drm_gpuva_fn_ops to call back into the driver providing the 
>> operations to
>> + * unmap and, if required, split existent mappings.
>> + *
>> + * Drivers may use these callbacks to update the GPU VA space right 
>> away within
>> + * the callback. In case the driver decides to copy and store the 
>> operations for
>> + * later processing neither this function nor &drm_gpuva_sm_map is 
>> allowed to be
>> + * called before the &drm_gpuva_manager's view of the GPU VA space 
>> was updated
>> + * with the previous set of operations. To update the 
>> &drm_gpuva_manager's view
>> + * of the GPU VA space drm_gpuva_insert(), drm_gpuva_destroy_locked() 
>> and/or
>> + * drm_gpuva_destroy_unlocked() should be used.
>> + *
>> + * A sequence of callbacks can contain unmap and remap operations, 
>> depending on
>> + * whether there are actual overlapping mappings to split.
>> + *
>> + * There can be an arbitrary amount of unmap operations and a maximum 
>> of two
>> + * remap operations.
>> + *
>> + * Returns: 0 on success or a negative error code
>> + */
>> +int
>> +drm_gpuva_sm_unmap(struct drm_gpuva_manager *mgr, void *priv,
>> +           u64 req_addr, u64 req_range)
>> +{
>> +    const struct drm_gpuva_fn_ops *ops = mgr->ops;
>> +
>> +    if (unlikely(!(ops && ops->sm_step_remap &&
>> +               ops->sm_step_unmap)))
>> +        return -EINVAL;
>> +
>> +    return __drm_gpuva_sm_unmap(mgr, ops, priv,
>> +                    req_addr, req_range);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_sm_unmap);
>> +
>> +static struct drm_gpuva_op *
>> +gpuva_op_alloc(struct drm_gpuva_manager *mgr)
>> +{
>> +    const struct drm_gpuva_fn_ops *fn = mgr->ops;
>> +    struct drm_gpuva_op *op;
>> +
>> +    if (fn && fn->op_alloc)
>> +        op = fn->op_alloc();
>> +    else
>> +        op = kzalloc(sizeof(*op), GFP_KERNEL);
>> +
>> +    if (unlikely(!op))
>> +        return NULL;
>> +
>> +    return op;
>> +}
>> +
>> +static void
>> +gpuva_op_free(struct drm_gpuva_manager *mgr,
>> +          struct drm_gpuva_op *op)
>> +{
>> +    const struct drm_gpuva_fn_ops *fn = mgr->ops;
>> +
>> +    if (fn && fn->op_free)
>> +        fn->op_free(op);
>> +    else
>> +        kfree(op);
>> +}
>> +
>> +static int
>> +drm_gpuva_sm_step(struct drm_gpuva_op *__op,
>> +          void *priv)
>> +{
>> +    struct {
>> +        struct drm_gpuva_manager *mgr;
>> +        struct drm_gpuva_ops *ops;
>> +    } *args = priv;
>> +    struct drm_gpuva_manager *mgr = args->mgr;
>> +    struct drm_gpuva_ops *ops = args->ops;
>> +    struct drm_gpuva_op *op;
>> +
>> +    op = gpuva_op_alloc(mgr);
>> +    if (unlikely(!op))
>> +        goto err;
>> +
>> +    memcpy(op, __op, sizeof(*op));
>> +
>> +    if (op->op == DRM_GPUVA_OP_REMAP) {
>> +        struct drm_gpuva_op_remap *__r = &__op->remap;
>> +        struct drm_gpuva_op_remap *r = &op->remap;
>> +
>> +        r->unmap = kmemdup(__r->unmap, sizeof(*r->unmap),
>> +                   GFP_KERNEL);
>> +        if (unlikely(!r->unmap))
>> +            goto err_free_op;
>> +
>> +        if (__r->prev) {
>> +            r->prev = kmemdup(__r->prev, sizeof(*r->prev),
>> +                      GFP_KERNEL);
>> +            if (unlikely(!r->prev))
>> +                goto err_free_unmap;
>> +        }
>> +
>> +        if (__r->next) {
>> +            r->next = kmemdup(__r->next, sizeof(*r->next),
>> +                      GFP_KERNEL);
>> +            if (unlikely(!r->next))
>> +                goto err_free_prev;
>> +        }
>> +    }
>> +
>> +    list_add_tail(&op->entry, &ops->list);
>> +
>> +    return 0;
>> +
>> +err_free_unmap:
>> +    kfree(op->remap.unmap);
>> +err_free_prev:
>> +    kfree(op->remap.prev);
>> +err_free_op:
>> +    gpuva_op_free(mgr, op);
>> +err:
>> +    return -ENOMEM;
>> +}
>> +
>> +static const struct drm_gpuva_fn_ops gpuva_list_ops = {
>> +    .sm_step_map = drm_gpuva_sm_step,
>> +    .sm_step_remap = drm_gpuva_sm_step,
>> +    .sm_step_unmap = drm_gpuva_sm_step,
>> +};
>> +
>> +/**
>> + * drm_gpuva_sm_map_ops_create - creates the &drm_gpuva_ops to split 
>> and merge
>> + * @mgr: the &drm_gpuva_manager representing the GPU VA space
>> + * @req_addr: the start address of the new mapping
>> + * @req_range: the range of the new mapping
>> + * @req_obj: the &drm_gem_object to map
>> + * @req_offset: the offset within the &drm_gem_object
>> + *
>> + * This function creates a list of operations to perform splitting 
>> and merging
>> + * of existent mapping(s) with the newly requested one.
>> + *
>> + * The list can be iterated with &drm_gpuva_for_each_op and must be 
>> processed
>> + * in the given order. It can contain map, unmap and remap 
>> operations, but it
>> + * also can be empty if no operation is required, e.g. if the 
>> requested mapping
>> + * already exists is the exact same way.
>> + *
>> + * There can be an arbitrary amount of unmap operations, a maximum of 
>> two remap
>> + * operations and a single map operation. The latter one represents 
>> the original
>> + * map operation requested by the caller.
>> + *
>> + * Note that before calling this function again with another mapping 
>> request it
>> + * is necessary to update the &drm_gpuva_manager's view of the GPU VA 
>> space. The
>> + * previously obtained operations must be either processed or 
>> abandoned. To
>> + * update the &drm_gpuva_manager's view of the GPU VA space 
>> drm_gpuva_insert(),
>> + * drm_gpuva_destroy_locked() and/or drm_gpuva_destroy_unlocked() 
>> should be
>> + * used.
>> + *
>> + * After the caller finished processing the returned &drm_gpuva_ops, 
>> they must
>> + * be freed with &drm_gpuva_ops_free.
>> + *
>> + * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR on 
>> failure
>> + */
>> +struct drm_gpuva_ops *
>> +drm_gpuva_sm_map_ops_create(struct drm_gpuva_manager *mgr,
>> +                u64 req_addr, u64 req_range,
>> +                struct drm_gem_object *req_obj, u64 req_offset)
>> +{
>> +    struct drm_gpuva_ops *ops;
>> +    struct {
>> +        struct drm_gpuva_manager *mgr;
>> +        struct drm_gpuva_ops *ops;
>> +    } args;
>> +    int ret;
>> +
>> +    ops = kzalloc(sizeof(*ops), GFP_KERNEL);
>> +    if (unlikely(!ops))
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    INIT_LIST_HEAD(&ops->list);
>> +
>> +    args.mgr = mgr;
>> +    args.ops = ops;
>> +
>> +    ret = __drm_gpuva_sm_map(mgr, &gpuva_list_ops, &args,
>> +                 req_addr, req_range,
>> +                 req_obj, req_offset);
>> +    if (ret)
>> +        goto err_free_ops;
>> +
>> +    return ops;
>> +
>> +err_free_ops:
>> +    drm_gpuva_ops_free(mgr, ops);
>> +    return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_sm_map_ops_create);
>> +
>> +/**
>> + * drm_gpuva_sm_unmap_ops_create - creates the &drm_gpuva_ops to 
>> split on unmap
>> + * @mgr: the &drm_gpuva_manager representing the GPU VA space
>> + * @req_addr: the start address of the range to unmap
>> + * @req_range: the range of the mappings to unmap
>> + *
>> + * This function creates a list of operations to perform unmapping 
>> and, if
>> + * required, splitting of the mappings overlapping the unmap range.
>> + *
>> + * The list can be iterated with &drm_gpuva_for_each_op and must be 
>> processed
>> + * in the given order. It can contain unmap and remap operations, 
>> depending on
>> + * whether there are actual overlapping mappings to split.
>> + *
>> + * There can be an arbitrary amount of unmap operations and a maximum 
>> of two
>> + * remap operations.
>> + *
>> + * Note that before calling this function again with another range to 
>> unmap it
>> + * is necessary to update the &drm_gpuva_manager's view of the GPU VA 
>> space. The
>> + * previously obtained operations must be processed or abandoned. To 
>> update the
>> + * &drm_gpuva_manager's view of the GPU VA space drm_gpuva_insert(),
>> + * drm_gpuva_destroy_locked() and/or drm_gpuva_destroy_unlocked() 
>> should be
>> + * used.
>> + *
>> + * After the caller finished processing the returned &drm_gpuva_ops, 
>> they must
>> + * be freed with &drm_gpuva_ops_free.
>> + *
>> + * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR on 
>> failure
>> + */
>> +struct drm_gpuva_ops *
>> +drm_gpuva_sm_unmap_ops_create(struct drm_gpuva_manager *mgr,
>> +                  u64 req_addr, u64 req_range)
>> +{
>> +    struct drm_gpuva_ops *ops;
>> +    struct {
>> +        struct drm_gpuva_manager *mgr;
>> +        struct drm_gpuva_ops *ops;
>> +    } args;
>> +    int ret;
>> +
>> +    ops = kzalloc(sizeof(*ops), GFP_KERNEL);
>> +    if (unlikely(!ops))
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    INIT_LIST_HEAD(&ops->list);
>> +
>> +    args.mgr = mgr;
>> +    args.ops = ops;
>> +
>> +    ret = __drm_gpuva_sm_unmap(mgr, &gpuva_list_ops, &args,
>> +                   req_addr, req_range);
>> +    if (ret)
>> +        goto err_free_ops;
>> +
>> +    return ops;
>> +
>> +err_free_ops:
>> +    drm_gpuva_ops_free(mgr, ops);
>> +    return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_sm_unmap_ops_create);
>> +
>> +/**
>> + * drm_gpuva_prefetch_ops_create - creates the &drm_gpuva_ops to 
>> prefetch
>> + * @mgr: the &drm_gpuva_manager representing the GPU VA space
>> + * @addr: the start address of the range to prefetch
>> + * @range: the range of the mappings to prefetch
>> + *
>> + * This function creates a list of operations to perform prefetching.
>> + *
>> + * The list can be iterated with &drm_gpuva_for_each_op and must be 
>> processed
>> + * in the given order. It can contain prefetch operations.
>> + *
>> + * There can be an arbitrary amount of prefetch operations.
>> + *
>> + * After the caller finished processing the returned &drm_gpuva_ops, 
>> they must
>> + * be freed with &drm_gpuva_ops_free.
>> + *
>> + * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR on 
>> failure
>> + */
>> +struct drm_gpuva_ops *
>> +drm_gpuva_prefetch_ops_create(struct drm_gpuva_manager *mgr,
>> +                  u64 addr, u64 range)
>> +{
>> +    struct drm_gpuva_ops *ops;
>> +    struct drm_gpuva_op *op;
>> +    struct drm_gpuva *va;
>> +    u64 end = addr + range;
>> +    int ret;
>> +
>> +    ops = kzalloc(sizeof(*ops), GFP_KERNEL);
>> +    if (!ops)
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    INIT_LIST_HEAD(&ops->list);
>> +
>> +    drm_gpuva_for_each_va_range(va, mgr, addr, end) {
>> +        op = gpuva_op_alloc(mgr);
>> +        if (!op) {
>> +            ret = -ENOMEM;
>> +            goto err_free_ops;
>> +        }
>> +
>> +        op->op = DRM_GPUVA_OP_PREFETCH;
>> +        op->prefetch.va = va;
>> +        list_add_tail(&op->entry, &ops->list);
>> +    }
>> +
>> +    return ops;
>> +
>> +err_free_ops:
>> +    drm_gpuva_ops_free(mgr, ops);
>> +    return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_prefetch_ops_create);
>> +
>> +/**
>> + * drm_gpuva_gem_unmap_ops_create - creates the &drm_gpuva_ops to 
>> unmap a GEM
>> + * @mgr: the &drm_gpuva_manager representing the GPU VA space
>> + * @obj: the &drm_gem_object to unmap
>> + *
>> + * This function creates a list of operations to perform unmapping 
>> for every
>> + * GPUVA attached to a GEM.
>> + *
>> + * The list can be iterated with &drm_gpuva_for_each_op and consists 
>> out of an
>> + * arbitrary amount of unmap operations.
>> + *
>> + * After the caller finished processing the returned &drm_gpuva_ops, 
>> they must
>> + * be freed with &drm_gpuva_ops_free.
>> + *
>> + * It is the callers responsibility to protect the GEMs GPUVA list 
>> against
>> + * concurrent access using the GEMs dma_resv lock.
>> + *
>> + * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR on 
>> failure
>> + */
>> +struct drm_gpuva_ops *
>> +drm_gpuva_gem_unmap_ops_create(struct drm_gpuva_manager *mgr,
>> +                   struct drm_gem_object *obj)
>> +{
>> +    struct drm_gpuva_ops *ops;
>> +    struct drm_gpuva_op *op;
>> +    struct drm_gpuva *va;
>> +    int ret;
>> +
>> +    if (drm_gpuva_manager_external_lock(mgr))
>> +        drm_gpuva_manager_ext_assert_held(mgr);
>> +    else
>> +        dma_resv_assert_held(obj->resv);
>> +
>> +    ops = kzalloc(sizeof(*ops), GFP_KERNEL);
>> +    if (!ops)
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    INIT_LIST_HEAD(&ops->list);
>> +
>> +    drm_gem_for_each_gpuva(va, obj) {
>> +        op = gpuva_op_alloc(mgr);
>> +        if (!op) {
>> +            ret = -ENOMEM;
>> +            goto err_free_ops;
>> +        }
>> +
>> +        op->op = DRM_GPUVA_OP_UNMAP;
>> +        op->unmap.va = va;
>> +        list_add_tail(&op->entry, &ops->list);
>> +    }
>> +
>> +    return ops;
>> +
>> +err_free_ops:
>> +    drm_gpuva_ops_free(mgr, ops);
>> +    return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_gem_unmap_ops_create);
>> +
>> +
>> +/**
>> + * drm_gpuva_ops_free - free the given &drm_gpuva_ops
>> + * @mgr: the &drm_gpuva_manager the ops were created for
>> + * @ops: the &drm_gpuva_ops to free
>> + *
>> + * Frees the given &drm_gpuva_ops structure including all the ops 
>> associated
>> + * with it.
>> + */
>> +void
>> +drm_gpuva_ops_free(struct drm_gpuva_manager *mgr,
>> +           struct drm_gpuva_ops *ops)
>> +{
>> +    struct drm_gpuva_op *op, *next;
>> +
>> +    drm_gpuva_for_each_op_safe(op, next, ops) {
>> +        list_del(&op->entry);
>> +
>> +        if (op->op == DRM_GPUVA_OP_REMAP) {
>> +            kfree(op->remap.prev);
>> +            kfree(op->remap.next);
>> +            kfree(op->remap.unmap);
>> +        }
>> +
>> +        gpuva_op_free(mgr, op);
>> +    }
>> +
>> +    kfree(ops);
>> +}
>> +EXPORT_SYMBOL(drm_gpuva_ops_free);
>> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
>> index 89e2706cac56..04dbe223b1a5 100644
>> --- a/include/drm/drm_drv.h
>> +++ b/include/drm/drm_drv.h
>> @@ -104,6 +104,12 @@ enum drm_driver_feature {
>>        * acceleration should be handled by two drivers that are 
>> connected using auxiliary bus.
>>        */
>>       DRIVER_COMPUTE_ACCEL            = BIT(7),
>> +    /**
>> +     * @DRIVER_GEM_GPUVA:
>> +     *
>> +     * Driver supports user defined GPU VA bindings for GEM objects.
>> +     */
>> +    DRIVER_GEM_GPUVA        = BIT(8),
>>       /* IMPORTANT: Below are all the legacy flags, add new ones 
>> above. */
>> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
>> index bbc721870c13..5ec8148a30ee 100644
>> --- a/include/drm/drm_gem.h
>> +++ b/include/drm/drm_gem.h
>> @@ -36,6 +36,8 @@
>>   #include <linux/kref.h>
>>   #include <linux/dma-resv.h>
>> +#include <linux/list.h>
>> +#include <linux/mutex.h>
>>   #include <drm/drm_vma_manager.h>
>> @@ -379,6 +381,18 @@ struct drm_gem_object {
>>        */
>>       struct dma_resv _resv;
>> +    /**
>> +     * @gpuva:
>> +     *
>> +     * Provides the list of GPU VAs attached to this GEM object.
>> +     *
>> +     * Drivers should lock list accesses with the GEMs &dma_resv lock
>> +     * (&drm_gem_object.resv).
>> +     */
>> +    struct {
>> +        struct list_head list;
>> +    } gpuva;
>> +
>>       /**
>>        * @funcs:
>>        *
>> @@ -526,4 +540,42 @@ unsigned long drm_gem_lru_scan(struct drm_gem_lru 
>> *lru,
>>   int drm_gem_evict(struct drm_gem_object *obj);
>> +/**
>> + * drm_gem_gpuva_init - initialize the gpuva list of a GEM object
>> + * @obj: the &drm_gem_object
>> + *
>> + * This initializes the &drm_gem_object's &drm_gpuva list.
>> + *
>> + * Calling this function is only necessary for drivers intending to 
>> support the
>> + * &drm_driver_feature DRIVER_GEM_GPUVA.
>> + */
>> +static inline void drm_gem_gpuva_init(struct drm_gem_object *obj)
>> +{
>> +    INIT_LIST_HEAD(&obj->gpuva.list);
>> +}
>> +
>> +/**
>> + * drm_gem_for_each_gpuva - iternator to walk over a list of gpuvas
> 
> s/iternator/iterator/. (multiple places) Although since "iterator" 
> typically refers to an object being iterated over, perhaps
> 
> "drm_gem_for_each_gpuva() - iterate over a list of gpuvas", (general 
> comment across the patch).
> 
>> + * @entry: &drm_gpuva structure to assign to in each iteration step
>> + * @obj: the &drm_gem_object the &drm_gpuvas to walk are associated with
>> + *
>> + * This iterator walks over all &drm_gpuva structures associated with 
>> the
>> + * &drm_gpuva_manager.
>> + */
>> +#define drm_gem_for_each_gpuva(entry__, obj__) \
>> +    list_for_each_entry(entry__, &(obj__)->gpuva.list, gem.entry)
>> +
>> +/**
>> + * drm_gem_for_each_gpuva_safe - iternator to safely walk over a list 
>> of gpuvas
>> + * @entry: &drm_gpuva structure to assign to in each iteration step
>> + * @next: &next &drm_gpuva to store the next step
>> + * @obj: the &drm_gem_object the &drm_gpuvas to walk are associated with
>> + *
>> + * This iterator walks over all &drm_gpuva structures associated with 
>> the
>> + * &drm_gem_object. It is implemented with 
>> list_for_each_entry_safe(), hence
>> + * it is save against removal of elements.
>> + */
>> +#define drm_gem_for_each_gpuva_safe(entry__, next__, obj__) \
>> +    list_for_each_entry_safe(entry__, next__, &(obj__)->gpuva.list, 
>> gem.entry)
>> +
>>   #endif /* __DRM_GEM_H__ */
>> diff --git a/include/drm/drm_gpuva_mgr.h b/include/drm/drm_gpuva_mgr.h
>> new file mode 100644
>> index 000000000000..4f23aaf726dd
>> --- /dev/null
>> +++ b/include/drm/drm_gpuva_mgr.h
>> @@ -0,0 +1,756 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +#ifndef __DRM_GPUVA_MGR_H__
>> +#define __DRM_GPUVA_MGR_H__
>> +
>> +/*
>> + * Copyright (c) 2022 Red Hat.
>> + *
>> + * 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, 
>> sublicense,
>> + * 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 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 NONINFRINGEMENT.  IN NO EVENT 
>> SHALL
>> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) 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/list.h>
>> +#include <linux/rbtree.h>
>> +#include <linux/types.h>
>> +
>> +#include <drm/drm_gem.h>
>> +
>> +struct drm_gpuva_manager;
>> +struct drm_gpuva_fn_ops;
>> +
>> +/**
>> + * enum drm_gpuva_flags - flags for struct drm_gpuva
>> + */
>> +enum drm_gpuva_flags {
>> +    /**
>> +     * @DRM_GPUVA_INVALIDATED:
>> +     *
>> +     * Flag indicating that the &drm_gpuva's backing GEM is invalidated.
>> +     */
>> +    DRM_GPUVA_INVALIDATED = (1 << 0),
>> +
>> +    /**
>> +     * @DRM_GPUVA_SPARSE:
>> +     *
>> +     * Flag indicating that the &drm_gpuva is a sparse mapping.
>> +     */
>> +    DRM_GPUVA_SPARSE = (1 << 1),
>> +
>> +    /**
>> +     * @DRM_GPUVA_USERBITS: user defined bits
>> +     */
>> +    DRM_GPUVA_USERBITS = (1 << 2),
>> +};
>> +
>> +/**
>> + * struct drm_gpuva - structure to track a GPU VA mapping
>> + *
>> + * This structure represents a GPU VA mapping and is associated with a
>> + * &drm_gpuva_manager.
>> + *
>> + * Typically, this structure is embedded in bigger driver structures.
>> + */
>> +struct drm_gpuva {
>> +    /**
>> +     * @mgr: the &drm_gpuva_manager this object is associated with
>> +     */
>> +    struct drm_gpuva_manager *mgr;
>> +
>> +    /**
>> +     * @flags: the &drm_gpuva_flags for this mapping
>> +     */
>> +    enum drm_gpuva_flags flags;
>> +
>> +    /**
>> +     * @va: structure containing the address and range of the &drm_gpuva
>> +     */
>> +    struct {
>> +        /**
>> +         * @addr: the start address
>> +         */
>> +        u64 addr;
>> +
>> +        /*
>> +         * @range: the range
>> +         */
>> +        u64 range;
>> +    } va;
>> +
>> +    /**
>> +     * @gem: structure containing the &drm_gem_object and it's offset
>> +     */
>> +    struct {
>> +        /**
>> +         * @offset: the offset within the &drm_gem_object
>> +         */
>> +        u64 offset;
>> +
>> +        /**
>> +         * @obj: the mapped &drm_gem_object
>> +         */
>> +        struct drm_gem_object *obj;
>> +
>> +        /**
>> +         * @entry: the &list_head to attach this object to a 
>> &drm_gem_object
>> +         */
>> +        struct list_head entry;
>> +    } gem;
>> +
>> +    /**
>> +     * @rb: structure containing data to store &drm_gpuvas in a rb-tree
>> +     */
>> +    struct {
>> +        /**
>> +         * @rb: the rb-tree node
>> +         */
>> +        struct rb_node node;
>> +
>> +        /**
>> +         * @entry: The &list_head to additionally connect &drm_gpuvas
>> +         * in the same order they appear in the interval tree. This is
>> +         * useful to keep iterating &drm_gpuvas from a start node found
>> +         * through the rb-tree while doing modifications on the rb-tree
>> +         * itself.
>> +         */
>> +        struct list_head entry;
>> +
>> +        /**
>> +         * @__subtree_last: needed by the interval tree, holding 
>> last-in-subtree
>> +         */
>> +        u64 __subtree_last;
>> +    } rb;
>> +};
>> +
>> +int drm_gpuva_insert(struct drm_gpuva_manager *mgr, struct drm_gpuva 
>> *va);
>> +void drm_gpuva_remove(struct drm_gpuva *va);
>> +
>> +void drm_gpuva_link(struct drm_gpuva *va);
>> +void drm_gpuva_unlink(struct drm_gpuva *va);
>> +
>> +struct drm_gpuva *drm_gpuva_find(struct drm_gpuva_manager *mgr,
>> +                 u64 addr, u64 range);
>> +struct drm_gpuva *drm_gpuva_find_first(struct drm_gpuva_manager *mgr,
>> +                       u64 addr, u64 range);
>> +struct drm_gpuva *drm_gpuva_find_prev(struct drm_gpuva_manager *mgr, 
>> u64 start);
>> +struct drm_gpuva *drm_gpuva_find_next(struct drm_gpuva_manager *mgr, 
>> u64 end);
>> +
>> +bool drm_gpuva_interval_empty(struct drm_gpuva_manager *mgr, u64 
>> addr, u64 range);
>> +
>> +static inline void drm_gpuva_init(struct drm_gpuva *va, u64 addr, u64 
>> range,
>> +                  struct drm_gem_object *obj, u64 offset)
>> +{
>> +    va->va.addr = addr;
>> +    va->va.range = range;
>> +    va->gem.obj = obj;
>> +    va->gem.offset = offset;
>> +}
>> +
>> +/**
>> + * drm_gpuva_invalidate - sets whether the backing GEM of this 
>> &drm_gpuva is
>> + * invalidated
>> + * @va: the &drm_gpuva to set the invalidate flag for
>> + * @invalidate: indicates whether the &drm_gpuva is invalidated
>> + */
>> +static inline void drm_gpuva_invalidate(struct drm_gpuva *va, bool 
>> invalidate)
>> +{
>> +    if (invalidate)
>> +        va->flags |= DRM_GPUVA_INVALIDATED;
>> +    else
>> +        va->flags &= ~DRM_GPUVA_INVALIDATED;
>> +}
>> +
>> +/**
>> + * drm_gpuva_invalidated - indicates whether the backing BO of this 
>> &drm_gpuva
>> + * is invalidated
>> + * @va: the &drm_gpuva to check
>> + */
>> +static inline bool drm_gpuva_invalidated(struct drm_gpuva *va)
>> +{
>> +    return va->flags & DRM_GPUVA_INVALIDATED;
>> +}
>> +
>> +#ifdef CONFIG_LOCKDEP
>> +typedef struct lockdep_map *lockdep_map_p;
>> +#define drm_gpuva_manager_ext_assert_held(mgr)        \
>> +    lockdep_assert(lock_is_held((mgr)->ext_lock) != LOCK_STATE_NOT_HELD)
>> +/**
>> + * drm_gpuva_manager_set_ext_lock - set the external lock according to
>> + * @DRM_GPUVA_MANAGER_LOCK_EXTERN
>> + * @mgr: the &drm_gpuva_manager to set the lock for
>> + * @lock: the lock to set
>> + *
>> + * If @DRM_GPUVA_MANAGER_LOCK_EXTERN is set, drivers need to call 
>> this function
>> + * to provide the lock used to lock linking and unlinking of 
>> &drm_gpuvas to the
>> + * &drm_gem_objects GPUVA list.
>> + */
>> +#define drm_gpuva_manager_set_ext_lock(mgr, lock)    \
>> +    (mgr)->ext_lock = &(lock)->dep_map
>> +#else
>> +typedef struct { /* nothing */ } lockdep_map_p;
>> +#define drm_gpuva_manager_ext_assert_held(mgr)        do { 
>> (void)(mgr); } while (0)
>> +#define drm_gpuva_manager_set_ext_lock(mgr, lock)    do { } while (0)
>> +#endif
>> +
>> +/**
>> + * enum drm_gpuva_manager_flags - the feature flags for the 
>> &drm_gpuva_manager
>> + */
>> +enum drm_gpuva_manager_flags {
>> +    /**
>> +     * @DRM_GPUVA_MANAGER_LOCK_EXTERN:
>> +     *
>> +     * Indicates the driver has it's own external lock for linking and
>> +     * unlinking &drm_gpuvas to the &drm_gem_objects GPUVA list.
>> +     *
>> +     * When setting this flag it is rquired to set a lock via
>> +     * drm_gpuva_set_ext_lock().
>> +     */
>> +    DRM_GPUVA_MANAGER_LOCK_EXTERN = (1 << 0),
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_manager - DRM GPU VA Manager
>> + *
>> + * The DRM GPU VA Manager keeps track of a GPU's virtual address 
>> space by using
>> + * &maple_tree structures. Typically, this structure is embedded in 
>> bigger
>> + * driver structures.
>> + *
>> + * Drivers can pass addresses and ranges in an arbitrary unit, e.g. 
>> bytes or
>> + * pages.
>> + *
>> + * There should be one manager instance per GPU virtual address space.
>> + */
>> +struct drm_gpuva_manager {
>> +    /**
>> +     * @name: the name of the DRM GPU VA space
>> +     */
>> +    const char *name;
>> +
>> +    /**
>> +     * @flags: the feature flags of the &drm_gpuva_manager
>> +     */
>> +    enum drm_gpuva_manager_flags flags;
>> +
>> +    /**
>> +     * @mm_start: start of the VA space
>> +     */
>> +    u64 mm_start;
>> +
>> +    /**
>> +     * @mm_range: length of the VA space
>> +     */
>> +    u64 mm_range;
>> +
>> +    /**
>> +     * @rb: structures to track &drm_gpuva entries
>> +     */
>> +    struct {
>> +        /**
>> +         * @tree: the rb-tree to track GPU VA mappings
>> +         */
>> +        struct rb_root_cached tree;
>> +
>> +        /**
>> +         * @list: the &list_head to track GPU VA mappings
>> +         */
>> +        struct list_head list;
>> +    } rb;
>> +
>> +    /**
>> +     * @kernel_alloc_node:
>> +     *
>> +     * &drm_gpuva representing the address space cutout reserved for
>> +     * the kernel
>> +     */
>> +    struct drm_gpuva kernel_alloc_node;
>> +
>> +    /**
>> +     * @ops: &drm_gpuva_fn_ops providing the split/merge steps to 
>> drivers
>> +     */
>> +    const struct drm_gpuva_fn_ops *ops;
>> +
>> +    /**
>> +     * @ext_lock: &lockdep_map according to 
>> @DRM_GPUVA_MANAGER_LOCK_EXTERN
>> +     */
>> +    lockdep_map_p ext_lock;
>> +};
>> +
>> +void drm_gpuva_manager_init(struct drm_gpuva_manager *mgr,
>> +                const char *name,
>> +                u64 start_offset, u64 range,
>> +                u64 reserve_offset, u64 reserve_range,
>> +                const struct drm_gpuva_fn_ops *ops,
>> +                enum drm_gpuva_manager_flags flags);
>> +void drm_gpuva_manager_destroy(struct drm_gpuva_manager *mgr);
>> +
>> +/**
>> + * drm_gpuva_manager_external_lock - indicates whether the
>> + * @DRM_GPUVA_MANAGER_LOCK_EXTERN flag is set
>> + * @mgr: the &drm_gpuva_manager to check the flag for
>> + */
>> +static inline bool drm_gpuva_manager_external_lock(struct 
>> drm_gpuva_manager *mgr)
>> +{
>> +    return mgr->flags & DRM_GPUVA_MANAGER_LOCK_EXTERN;
>> +}
>> +
>> +/**
>> + * drm_gpuva_for_each_va_range - iternator to walk over a range of 
>> &drm_gpuvas
>> + * @va__: &drm_gpuva structure to assign to in each iteration step
>> + * @mgr__: &drm_gpuva_manager to walk over
>> + * @start__: starting offset, the first gpuva will overlap this
>> + * @end__: ending offset, the last gpuva will start before this (but may
>> + * overlap)
>> + *
>> + * This iterator walks over all &drm_gpuvas in the &drm_gpuva_manager 
>> that lie
>> + * between @start__ and @end__. It is implemented similarly to 
>> list_for_each(),
>> + * but is using the &drm_gpuva_manager's internal interval tree to 
>> accelerate
>> + * the search for the starting &drm_gpuva, and hence isn't safe 
>> against removal
>> + * of elements. It assumes that @end__ is within (or is the upper 
>> limit of) the
>> + * &drm_gpuva_manager. This iterator does not skip over the 
>> &drm_gpuva_manager's
>> + * @kernel_alloc_node.
>> + */
>> +#define drm_gpuva_for_each_va_range(va__, mgr__, start__, end__) \
>> +    for (va__ = drm_gpuva_find_first((mgr__), (start__), (end__)); \
>> +         va__ && (va__->va.addr < (end__)) && \
>> +         !list_entry_is_head(va__, &(mgr__)->rb.list, rb.entry); \
>> +         va__ = list_next_entry(va__, rb.entry))
>> +
>> +/**
>> + * drm_gpuva_for_each_va_range_safe - iternator to safely walk over a 
>> range of
>> + * &drm_gpuvas
>> + * @va__: &drm_gpuva to assign to in each iteration step
>> + * @next__: another &drm_gpuva to use as temporary storage
>> + * @mgr__: &drm_gpuva_manager to walk over
>> + * @start__: starting offset, the first gpuva will overlap this
>> + * @end__: ending offset, the last gpuva will start before this (but may
>> + * overlap)
>> + *
>> + * This iterator walks over all &drm_gpuvas in the &drm_gpuva_manager 
>> that lie
>> + * between @start__ and @end__. It is implemented similarly to
>> + * list_for_each_safe(), but is using the &drm_gpuva_manager's 
>> internal interval
>> + * tree to accelerate the search for the starting &drm_gpuva, and 
>> hence is safe
>> + * against removal of elements. It assumes that @end__ is within (or 
>> is the
>> + * upper limit of) the &drm_gpuva_manager. This iterator does not 
>> skip over the
>> + * &drm_gpuva_manager's @kernel_alloc_node.
>> + */
>> +#define drm_gpuva_for_each_va_range_safe(va__, next__, mgr__, 
>> start__, end__) \
>> +    for (va__ = drm_gpuva_find_first((mgr__), (start__), (end__)), \
>> +         next__ = va ? list_next_entry(va__, rb.entry) : NULL; \
>> +         va__ && (va__->va.addr < (end__)) && \
>> +         !list_entry_is_head(va__, &(mgr__)->rb.list, rb.entry); \
>> +         va__ = next__, next__ = list_next_entry(va__, rb.entry))
>> +
>> +/**
>> + * drm_gpuva_for_each_va - iternator to walk over all &drm_gpuvas
>> + * @va__: &drm_gpuva to assign to in each iteration step
>> + * @mgr__: &drm_gpuva_manager to walk over
>> + *
>> + * This iterator walks over all &drm_gpuva structures associated with 
>> the given
>> + * &drm_gpuva_manager.
>> + */
>> +#define drm_gpuva_for_each_va(va__, mgr__) \
>> +    list_for_each_entry(va__, &(mgr__)->rb.list, rb.entry)
>> +
>> +/**
>> + * drm_gpuva_for_each_va_safe - iternator to safely walk over all 
>> &drm_gpuvas
>> + * @va__: &drm_gpuva to assign to in each iteration step
>> + * @next__: another &drm_gpuva to use as temporary storage
>> + * @mgr__: &drm_gpuva_manager to walk over
>> + *
>> + * This iterator walks over all &drm_gpuva structures associated with 
>> the given
>> + * &drm_gpuva_manager. It is implemented with 
>> list_for_each_entry_safe(), and
>> + * hence safe against the removal of elements.
>> + */
>> +#define drm_gpuva_for_each_va_safe(va__, next__, mgr__) \
>> +    list_for_each_entry_safe(va__, next__, &(mgr__)->rb.list, rb.entry)
>> +
>> +/**
>> + * enum drm_gpuva_op_type - GPU VA operation type
>> + *
>> + * Operations to alter the GPU VA mappings tracked by the 
>> &drm_gpuva_manager.
>> + */
>> +enum drm_gpuva_op_type {
>> +    /**
>> +     * @DRM_GPUVA_OP_MAP: the map op type
>> +     */
>> +    DRM_GPUVA_OP_MAP,
>> +
>> +    /**
>> +     * @DRM_GPUVA_OP_REMAP: the remap op type
>> +     */
>> +    DRM_GPUVA_OP_REMAP,
>> +
>> +    /**
>> +     * @DRM_GPUVA_OP_UNMAP: the unmap op type
>> +     */
>> +    DRM_GPUVA_OP_UNMAP,
>> +
>> +    /**
>> +     * @DRM_GPUVA_OP_PREFETCH: the prefetch op type
>> +     */
>> +    DRM_GPUVA_OP_PREFETCH,
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_op_map - GPU VA map operation
>> + *
>> + * This structure represents a single map operation generated by the
>> + * DRM GPU VA manager.
>> + */
>> +struct drm_gpuva_op_map {
>> +    /**
>> +     * @va: structure containing address and range of a map
>> +     * operation
>> +     */
>> +    struct {
>> +        /**
>> +         * @addr: the base address of the new mapping
>> +         */
>> +        u64 addr;
>> +
>> +        /**
>> +         * @range: the range of the new mapping
>> +         */
>> +        u64 range;
>> +    } va;
>> +
>> +    /**
>> +     * @gem: structure containing the &drm_gem_object and it's offset
>> +     */
>> +    struct {
>> +        /**
>> +         * @offset: the offset within the &drm_gem_object
>> +         */
>> +        u64 offset;
>> +
>> +        /**
>> +         * @obj: the &drm_gem_object to map
>> +         */
>> +        struct drm_gem_object *obj;
>> +    } gem;
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_op_unmap - GPU VA unmap operation
>> + *
>> + * This structure represents a single unmap operation generated by the
>> + * DRM GPU VA manager.
>> + */
>> +struct drm_gpuva_op_unmap {
>> +    /**
>> +     * @va: the &drm_gpuva to unmap
>> +     */
>> +    struct drm_gpuva *va;
>> +
>> +    /**
>> +     * @keep:
>> +     *
>> +     * Indicates whether this &drm_gpuva is physically contiguous 
>> with the
>> +     * original mapping request.
>> +     *
>> +     * Optionally, if &keep is set, drivers may keep the actual page 
>> table
>> +     * mappings for this &drm_gpuva, adding the missing page table 
>> entries
>> +     * only and update the &drm_gpuva_manager accordingly.
>> +     */
>> +    bool keep;
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_op_remap - GPU VA remap operation
>> + *
>> + * This represents a single remap operation generated by the DRM GPU 
>> VA manager.
>> + *
>> + * A remap operation is generated when an existing GPU VA mmapping is 
>> split up
>> + * by inserting a new GPU VA mapping or by partially unmapping existent
>> + * mapping(s), hence it consists of a maximum of two map and one unmap
>> + * operation.
>> + *
>> + * The @unmap operation takes care of removing the original existing 
>> mapping.
>> + * @prev is used to remap the preceding part, @next the subsequent part.
>> + *
>> + * If either a new mapping's start address is aligned with the start 
>> address
>> + * of the old mapping or the new mapping's end address is aligned 
>> with the
>> + * end address of the old mapping, either @prev or @next is NULL.
>> + *
>> + * Note, the reason for a dedicated remap operation, rather than 
>> arbitrary
>> + * unmap and map operations, is to give drivers the chance of 
>> extracting driver
>> + * specific data for creating the new mappings from the unmap 
>> operations's
>> + * &drm_gpuva structure which typically is embedded in larger driver 
>> specific
>> + * structures.
>> + */
>> +struct drm_gpuva_op_remap {
>> +    /**
>> +     * @prev: the preceding part of a split mapping
>> +     */
>> +    struct drm_gpuva_op_map *prev;
>> +
>> +    /**
>> +     * @next: the subsequent part of a split mapping
>> +     */
>> +    struct drm_gpuva_op_map *next;
>> +
>> +    /**
>> +     * @unmap: the unmap operation for the original existing mapping
>> +     */
>> +    struct drm_gpuva_op_unmap *unmap;
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_op_prefetch - GPU VA prefetch operation
>> + *
>> + * This structure represents a single prefetch operation generated by 
>> the
>> + * DRM GPU VA manager.
>> + */
>> +struct drm_gpuva_op_prefetch {
>> +    /**
>> +     * @va: the &drm_gpuva to prefetch
>> +     */
>> +    struct drm_gpuva *va;
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_op - GPU VA operation
>> + *
>> + * This structure represents a single generic operation.
>> + *
>> + * The particular type of the operation is defined by @op.
>> + */
>> +struct drm_gpuva_op {
>> +    /**
>> +     * @entry:
>> +     *
>> +     * The &list_head used to distribute instances of this struct within
>> +     * &drm_gpuva_ops.
>> +     */
>> +    struct list_head entry;
>> +
>> +    /**
>> +     * @op: the type of the operation
>> +     */
>> +    enum drm_gpuva_op_type op;
>> +
>> +    union {
>> +        /**
>> +         * @map: the map operation
>> +         */
>> +        struct drm_gpuva_op_map map;
>> +
>> +        /**
>> +         * @remap: the remap operation
>> +         */
>> +        struct drm_gpuva_op_remap remap;
>> +
>> +        /**
>> +         * @unmap: the unmap operation
>> +         */
>> +        struct drm_gpuva_op_unmap unmap;
>> +
>> +        /**
>> +         * @prefetch: the prefetch operation
>> +         */
>> +        struct drm_gpuva_op_prefetch prefetch;
>> +    };
>> +};
>> +
>> +/**
>> + * struct drm_gpuva_ops - wraps a list of &drm_gpuva_op
>> + */
>> +struct drm_gpuva_ops {
>> +    /**
>> +     * @list: the &list_head
>> +     */
>> +    struct list_head list;
>> +};
>> +
>> +/**
>> + * drm_gpuva_for_each_op - iterator to walk over &drm_gpuva_ops
>> + * @op: &drm_gpuva_op to assign in each iteration step
>> + * @ops: &drm_gpuva_ops to walk
>> + *
>> + * This iterator walks over all ops within a given list of operations.
>> + */
>> +#define drm_gpuva_for_each_op(op, ops) list_for_each_entry(op, 
>> &(ops)->list, entry)
>> +
>> +/**
>> + * drm_gpuva_for_each_op_safe - iterator to safely walk over 
>> &drm_gpuva_ops
>> + * @op: &drm_gpuva_op to assign in each iteration step
>> + * @next: &next &drm_gpuva_op to store the next step
>> + * @ops: &drm_gpuva_ops to walk
>> + *
>> + * This iterator walks over all ops within a given list of 
>> operations. It is
>> + * implemented with list_for_each_safe(), so save against removal of 
>> elements.
>> + */
>> +#define drm_gpuva_for_each_op_safe(op, next, ops) \
>> +    list_for_each_entry_safe(op, next, &(ops)->list, entry)
>> +
>> +/**
>> + * drm_gpuva_for_each_op_from_reverse - iterate backwards from the 
>> given point
>> + * @op: &drm_gpuva_op to assign in each iteration step
>> + * @ops: &drm_gpuva_ops to walk
>> + *
>> + * This iterator walks over all ops within a given list of operations 
>> beginning
>> + * from the given operation in reverse order.
>> + */
>> +#define drm_gpuva_for_each_op_from_reverse(op, ops) \
>> +    list_for_each_entry_from_reverse(op, &(ops)->list, entry)
>> +
>> +/**
>> + * drm_gpuva_first_op - returns the first &drm_gpuva_op from 
>> &drm_gpuva_ops
>> + * @ops: the &drm_gpuva_ops to get the fist &drm_gpuva_op from
>> + */
>> +#define drm_gpuva_first_op(ops) \
>> +    list_first_entry(&(ops)->list, struct drm_gpuva_op, entry)
>> +
>> +/**
>> + * drm_gpuva_last_op - returns the last &drm_gpuva_op from 
>> &drm_gpuva_ops
>> + * @ops: the &drm_gpuva_ops to get the last &drm_gpuva_op from
>> + */
>> +#define drm_gpuva_last_op(ops) \
>> +    list_last_entry(&(ops)->list, struct drm_gpuva_op, entry)
>> +
>> +/**
>> + * drm_gpuva_prev_op - previous &drm_gpuva_op in the list
>> + * @op: the current &drm_gpuva_op
>> + */
>> +#define drm_gpuva_prev_op(op) list_prev_entry(op, entry)
>> +
>> +/**
>> + * drm_gpuva_next_op - next &drm_gpuva_op in the list
>> + * @op: the current &drm_gpuva_op
>> + */
>> +#define drm_gpuva_next_op(op) list_next_entry(op, entry)
>> +
>> +struct drm_gpuva_ops *
>> +drm_gpuva_sm_map_ops_create(struct drm_gpuva_manager *mgr,
>> +                u64 addr, u64 range,
>> +                struct drm_gem_object *obj, u64 offset);
>> +struct drm_gpuva_ops *
>> +drm_gpuva_sm_unmap_ops_create(struct drm_gpuva_manager *mgr,
>> +                  u64 addr, u64 range);
>> +
>> +struct drm_gpuva_ops *
>> +drm_gpuva_prefetch_ops_create(struct drm_gpuva_manager *mgr,
>> +                 u64 addr, u64 range);
>> +
>> +struct drm_gpuva_ops *
>> +drm_gpuva_gem_unmap_ops_create(struct drm_gpuva_manager *mgr,
>> +                   struct drm_gem_object *obj);
>> +
>> +void drm_gpuva_ops_free(struct drm_gpuva_manager *mgr,
>> +            struct drm_gpuva_ops *ops);
>> +
>> +static inline void drm_gpuva_init_from_op(struct drm_gpuva *va,
>> +                      struct drm_gpuva_op_map *op)
>> +{
>> +    drm_gpuva_init(va, op->va.addr, op->va.range,
>> +               op->gem.obj, op->gem.offset);
>> +}
>> +
>> +/**
>> + * struct drm_gpuva_fn_ops - callbacks for split/merge steps
>> + *
>> + * This structure defines the callbacks used by &drm_gpuva_sm_map and
>> + * &drm_gpuva_sm_unmap to provide the split/merge steps for map and 
>> unmap
>> + * operations to drivers.
>> + */
>> +struct drm_gpuva_fn_ops {
>> +    /**
>> +     * @op_alloc: called when the &drm_gpuva_manager allocates
>> +     * a struct drm_gpuva_op
>> +     *
>> +     * Some drivers may want to embed struct drm_gpuva_op into driver
>> +     * specific structures. By implementing this callback drivers can
>> +     * allocate memory accordingly.
>> +     *
>> +     * This callback is optional.
>> +     */
>> +    struct drm_gpuva_op *(*op_alloc)(void);
>> +
>> +    /**
>> +     * @op_free: called when the &drm_gpuva_manager frees a
>> +     * struct drm_gpuva_op
>> +     *
>> +     * Some drivers may want to embed struct drm_gpuva_op into driver
>> +     * specific structures. By implementing this callback drivers can
>> +     * free the previously allocated memory accordingly.
>> +     *
>> +     * This callback is optional.
>> +     */
>> +    void (*op_free)(struct drm_gpuva_op *op);
>> +
>> +    /**
>> +     * @sm_step_map: called from &drm_gpuva_sm_map to finally insert the
>> +     * mapping once all previous steps were completed
>> +     *
>> +     * The &priv pointer matches the one the driver passed to
>> +     * &drm_gpuva_sm_map or &drm_gpuva_sm_unmap, respectively.
>> +     *
>> +     * Can be NULL if &drm_gpuva_sm_map is used.
>> +     */
>> +    int (*sm_step_map)(struct drm_gpuva_op *op, void *priv);
>> +
>> +    /**
>> +     * @sm_step_remap: called from &drm_gpuva_sm_map and
>> +     * &drm_gpuva_sm_unmap to split up an existent mapping
>> +     *
>> +     * This callback is called when existent mapping needs to be 
>> split up.
>> +     * This is the case when either a newly requested mapping 
>> overlaps or
>> +     * is enclosed by an existent mapping or a partial unmap of an 
>> existent
>> +     * mapping is requested.
>> +     *
>> +     * The &priv pointer matches the one the driver passed to
>> +     * &drm_gpuva_sm_map or &drm_gpuva_sm_unmap, respectively.
>> +     *
>> +     * Can be NULL if neither &drm_gpuva_sm_map nor 
>> &drm_gpuva_sm_unmap is
>> +     * used.
>> +     */
>> +    int (*sm_step_remap)(struct drm_gpuva_op *op, void *priv);
>> +
>> +    /**
>> +     * @sm_step_unmap: called from &drm_gpuva_sm_map and
>> +     * &drm_gpuva_sm_unmap to unmap an existent mapping
>> +     *
>> +     * This callback is called when existent mapping needs to be 
>> unmapped.
>> +     * This is the case when either a newly requested mapping 
>> encloses an
>> +     * existent mapping or an unmap of an existent mapping is requested.
>> +     *
>> +     * The &priv pointer matches the one the driver passed to
>> +     * &drm_gpuva_sm_map or &drm_gpuva_sm_unmap, respectively.
>> +     *
>> +     * Can be NULL if neither &drm_gpuva_sm_map nor 
>> &drm_gpuva_sm_unmap is
>> +     * used.
>> +     */
>> +    int (*sm_step_unmap)(struct drm_gpuva_op *op, void *priv);
>> +};
>> +
>> +int drm_gpuva_sm_map(struct drm_gpuva_manager *mgr, void *priv,
>> +             u64 addr, u64 range,
>> +             struct drm_gem_object *obj, u64 offset);
>> +
>> +int drm_gpuva_sm_unmap(struct drm_gpuva_manager *mgr, void *priv,
>> +               u64 addr, u64 range);
>> +
>> +void drm_gpuva_map(struct drm_gpuva_manager *mgr,
>> +           struct drm_gpuva *va,
>> +           struct drm_gpuva_op_map *op);
> Missing newline
>> +void drm_gpuva_remap(struct drm_gpuva *prev,
>> +             struct drm_gpuva *next,
>> +             struct drm_gpuva_op_remap *op);
> Missing newline
>> +void drm_gpuva_unmap(struct drm_gpuva_op_unmap *op);
>> +
>> +#endif /* __DRM_GPUVA_MGR_H__ */
>