[drm-misc-next,v6,1/6] drm/gpuvm: add common dma-resv per struct drm_gpuvm

  Provide a common dma-resv for GEM objects not being used outside of this
GPU-VM. This is used in a subsequent patch to generalize dma-resv,
external and evicted object handling and GEM validation.

Signed-off-by: Danilo Krummrich <dakr@redhat.com>
---
 drivers/gpu/drm/drm_gpuvm.c            | 56 +++++++++++++++++++++++++-
 drivers/gpu/drm/nouveau/nouveau_uvmm.c | 13 +++++-
 include/drm/drm_gpuvm.h                | 35 +++++++++++++++-
 3 files changed, 99 insertions(+), 5 deletions(-)
  

On Mon, 2023-10-09 at 01:32 +0200, Danilo Krummrich wrote:
> Provide a common dma-resv for GEM objects not being used outside of
> this
> GPU-VM. This is used in a subsequent patch to generalize dma-resv,
> external and evicted object handling and GEM validation.
> 
> Signed-off-by: Danilo Krummrich <dakr@redhat.com>
> ---
>  drivers/gpu/drm/drm_gpuvm.c            | 56
> +++++++++++++++++++++++++-
>  drivers/gpu/drm/nouveau/nouveau_uvmm.c | 13 +++++-
>  include/drm/drm_gpuvm.h                | 35 +++++++++++++++-
>  3 files changed, 99 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gpuvm.c
> b/drivers/gpu/drm/drm_gpuvm.c
> index 02ecb45a2544..ebda9d594165 100644
> --- a/drivers/gpu/drm/drm_gpuvm.c
> +++ b/drivers/gpu/drm/drm_gpuvm.c
> @@ -61,6 +61,15 @@
>   * 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.
> + *
> + * &drm_gem_objects which are private to a single VM can share a
> common
> + * &dma_resv in order to improve locking efficiency (e.g. with
> &drm_exec).
> + * For this purpose drivers must pass a &drm_gem_object to
> drm_gpuvm_init(), in
> + * the following called 'root object', which serves as the container

Nit: Perhaps resv object altough it might typically be the root page-
table object, that doesn't have any meaning to drm_gpuvm, which uses it
solely as a container for the resv?

> of the
> + * GPUVM's shared &dma_resv. This root object can be a driver
> specific
> + * &drm_gem_object, such as the &drm_gem_object containing the root
> page table,
> + * but it can also be a 'dummy' object, which can be allocated with
> + * drm_gpuvm_root_object_alloc().
>   */
>  
>  /**
> @@ -652,9 +661,47 @@ drm_gpuvm_range_valid(struct drm_gpuvm *gpuvm,
>                !drm_gpuvm_in_kernel_node(gpuvm, addr, range);
>  }
>  
> +static void
> +drm_gpuvm_gem_object_free(struct drm_gem_object *obj)
> +{
> +       drm_gem_object_release(obj);
> +       kfree(obj);
> +}
> +
> +static const struct drm_gem_object_funcs drm_gpuvm_object_funcs = {
> +       .free = drm_gpuvm_gem_object_free,
> +};
> +
> +/**
> + * drm_gpuvm_root_object_alloc() - allocate a dummy &drm_gem_object
> + * @drm: the drivers &drm_device
> + *
> + * Allocates a dummy &drm_gem_object which can be passed to
> drm_gpuvm_init() in
> + * order to serve as root GEM object providing the &drm_resv shared
> across
> + * &drm_gem_objects local to a single GPUVM.
> + *
> + * Returns: the &drm_gem_object on success, NULL on failure
> + */
> +struct drm_gem_object *
> +drm_gpuvm_root_object_alloc(struct drm_device *drm)
> +{
> +       struct drm_gem_object *obj;
> +
> +       obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> +       if (!obj)
> +               return NULL;
> +
> +       obj->funcs = &drm_gpuvm_object_funcs;
> +       drm_gem_private_object_init(drm, obj, 0);
> +
> +       return obj;
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_root_object_alloc);
> +
>  /**
>   * drm_gpuvm_init() - initialize a &drm_gpuvm
>   * @gpuvm: pointer to the &drm_gpuvm to initialize
> + * @r_obj: the root &drm_gem_object providing the GPUVM's common
> &dma_resv
>   * @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
> @@ -668,7 +715,7 @@ drm_gpuvm_range_valid(struct drm_gpuvm *gpuvm,
>   * &name is expected to be managed by the surrounding driver
> structures.
>   */
>  void
> -drm_gpuvm_init(struct drm_gpuvm *gpuvm,
> +drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct drm_gem_object
> *r_obj,
>                const char *name,
>                u64 start_offset, u64 range,
>                u64 reserve_offset, u64 reserve_range,
> @@ -683,6 +730,9 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm,
>  
>         gpuvm->name = name ? name : "unknown";
>         gpuvm->ops = ops;
> +       gpuvm->r_obj = r_obj;
> +
> +       drm_gem_object_get(r_obj);
>  
>         memset(&gpuvm->kernel_alloc_node, 0, sizeof(struct
> drm_gpuva));
>  
> @@ -713,7 +763,9 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
>                 __drm_gpuva_remove(&gpuvm->kernel_alloc_node);
>  
>         WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
> -            "GPUVA tree is not empty, potentially leaking memory.");
> +            "GPUVA tree is not empty, potentially leaking
> memory.\n");

Should we cache the drm device in struct drm_gpuvm and use drm_warn()
here instead of WARN?

> +
> +       drm_gem_object_put(gpuvm->r_obj);
>  }
>  EXPORT_SYMBOL_GPL(drm_gpuvm_destroy);
>  
> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> index 5cf892c50f43..4dea847ef989 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> @@ -1808,8 +1808,9 @@ int
>  nouveau_uvmm_init(struct nouveau_uvmm *uvmm, struct nouveau_cli
> *cli,
>                   u64 kernel_managed_addr, u64 kernel_managed_size)
>  {
> -       int ret;
> +       struct drm_gem_object *r_obj;
>         u64 kernel_managed_end = kernel_managed_addr +
> kernel_managed_size;
> +       int ret;
>  
>         mutex_init(&uvmm->mutex);
>         dma_resv_init(&uvmm->resv);
> @@ -1833,14 +1834,22 @@ nouveau_uvmm_init(struct nouveau_uvmm *uvmm,
> struct nouveau_cli *cli,
>                 goto out_unlock;
>         }
>  
> +       r_obj = drm_gpuvm_root_object_alloc(cli->drm->dev);
> +       if (!r_obj) {
> +               ret = -ENOMEM;
> +               goto out_unlock;
> +       }
> +
>         uvmm->kernel_managed_addr = kernel_managed_addr;
>         uvmm->kernel_managed_size = kernel_managed_size;
>  
> -       drm_gpuvm_init(&uvmm->base, cli->name,
> +       drm_gpuvm_init(&uvmm->base, r_obj, cli->name,
>                        NOUVEAU_VA_SPACE_START,
>                        NOUVEAU_VA_SPACE_END,
>                        kernel_managed_addr, kernel_managed_size,
>                        NULL);
> +       /* GPUVM takes care from here on. */
> +       drm_gem_object_put(r_obj);
>  
>         ret = nvif_vmm_ctor(&cli->mmu, "uvmm",
>                             cli->vmm.vmm.object.oclass, RAW,
> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
> index c7ed6bf441d4..0aec14d8b259 100644
> --- a/include/drm/drm_gpuvm.h
> +++ b/include/drm/drm_gpuvm.h
> @@ -238,9 +238,15 @@ struct drm_gpuvm {
>          * @ops: &drm_gpuvm_ops providing the split/merge steps to
> drivers
>          */
>         const struct drm_gpuvm_ops *ops;
> +
> +       /**
> +        * @r_obj: Root GEM object; representing the GPUVM's common
> &dma_resv.
> +        */
> +       struct drm_gem_object *r_obj;
>  };
>  
> -void drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name,
> +void drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct drm_gem_object
> *r_obj,
> +                   const char *name,
>                     u64 start_offset, u64 range,
>                     u64 reserve_offset, u64 reserve_range,
>                     const struct drm_gpuvm_ops *ops);
> @@ -248,6 +254,33 @@ void drm_gpuvm_destroy(struct drm_gpuvm *gpuvm);
>  
>  bool drm_gpuvm_interval_empty(struct drm_gpuvm *gpuvm, u64 addr, u64
> range);
>  
> +struct drm_gem_object *
> +drm_gpuvm_root_object_alloc(struct drm_device *drm);
> +
> +/**
> + * drm_gpuvm_resv() - returns the &drm_gpuvm's &dma_resv
> + * @gpuvm__: the &drm_gpuvm
> + *
> + * Returns: a pointer to the &drm_gpuvm's shared &dma_resv
> + */
> +#define drm_gpuvm_resv(gpuvm__) ((gpuvm__)->r_obj->resv)
> +
> +/**
> + * drm_gpuvm_resv_obj() - returns the &drm_gem_object holding the
> &drm_gpuvm's
> + * &dma_resv
> + * @gpuvm__: the &drm_gpuvm
> + *
> + * Returns: a pointer to the &drm_gem_object holding the
> &drm_gpuvm's shared
> + * &dma_resv
> + */
> +#define drm_gpuvm_resv_obj(gpuvm__) ((gpuvm__)->r_obj)
> +
> +#define drm_gpuvm_resv_held(gpuvm__) \
> +       dma_resv_held(drm_gpuvm_resv(gpuvm__))
> +
> +#define drm_gpuvm_resv_assert_held(gpuvm__) \
> +       dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
> +
>  static inline struct drm_gpuva *
>  __drm_gpuva_next(struct drm_gpuva *va)
>  {

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
  

On 10/13/23 13:38, Thomas Hellström wrote:
> On Mon, 2023-10-09 at 01:32 +0200, Danilo Krummrich wrote:
>> Provide a common dma-resv for GEM objects not being used outside of
>> this
>> GPU-VM. This is used in a subsequent patch to generalize dma-resv,
>> external and evicted object handling and GEM validation.
>>
>> Signed-off-by: Danilo Krummrich <dakr@redhat.com>
>> ---
>>   drivers/gpu/drm/drm_gpuvm.c            | 56
>> +++++++++++++++++++++++++-
>>   drivers/gpu/drm/nouveau/nouveau_uvmm.c | 13 +++++-
>>   include/drm/drm_gpuvm.h                | 35 +++++++++++++++-
>>   3 files changed, 99 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_gpuvm.c
>> b/drivers/gpu/drm/drm_gpuvm.c
>> index 02ecb45a2544..ebda9d594165 100644
>> --- a/drivers/gpu/drm/drm_gpuvm.c
>> +++ b/drivers/gpu/drm/drm_gpuvm.c
>> @@ -61,6 +61,15 @@
>>    * 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.
>> + *
>> + * &drm_gem_objects which are private to a single VM can share a
>> common
>> + * &dma_resv in order to improve locking efficiency (e.g. with
>> &drm_exec).
>> + * For this purpose drivers must pass a &drm_gem_object to
>> drm_gpuvm_init(), in
>> + * the following called 'root object', which serves as the container
> 
> Nit: Perhaps resv object altough it might typically be the root page-
> table object, that doesn't have any meaning to drm_gpuvm, which uses it
> solely as a container for the resv?

With "root" I didn't want to refer to the object representing the root
page-table object, but being *the* object every other (internal) object
needs to keep a reference to. Maybe I should be more explicit here and say
that drivers need to make sure every internal object requires a reference
to take a reference to this root object.

> 
>> of the
>> + * GPUVM's shared &dma_resv. This root object can be a driver
>> specific
>> + * &drm_gem_object, such as the &drm_gem_object containing the root
>> page table,
>> + * but it can also be a 'dummy' object, which can be allocated with
>> + * drm_gpuvm_root_object_alloc().
>>    */
>>   
>>   /**
>> @@ -652,9 +661,47 @@ drm_gpuvm_range_valid(struct drm_gpuvm *gpuvm,
>>                 !drm_gpuvm_in_kernel_node(gpuvm, addr, range);
>>   }
>>   
>> +static void
>> +drm_gpuvm_gem_object_free(struct drm_gem_object *obj)
>> +{
>> +       drm_gem_object_release(obj);
>> +       kfree(obj);
>> +}
>> +
>> +static const struct drm_gem_object_funcs drm_gpuvm_object_funcs = {
>> +       .free = drm_gpuvm_gem_object_free,
>> +};
>> +
>> +/**
>> + * drm_gpuvm_root_object_alloc() - allocate a dummy &drm_gem_object
>> + * @drm: the drivers &drm_device
>> + *
>> + * Allocates a dummy &drm_gem_object which can be passed to
>> drm_gpuvm_init() in
>> + * order to serve as root GEM object providing the &drm_resv shared
>> across
>> + * &drm_gem_objects local to a single GPUVM.
>> + *
>> + * Returns: the &drm_gem_object on success, NULL on failure
>> + */
>> +struct drm_gem_object *
>> +drm_gpuvm_root_object_alloc(struct drm_device *drm)
>> +{
>> +       struct drm_gem_object *obj;
>> +
>> +       obj = kzalloc(sizeof(*obj), GFP_KERNEL);
>> +       if (!obj)
>> +               return NULL;
>> +
>> +       obj->funcs = &drm_gpuvm_object_funcs;
>> +       drm_gem_private_object_init(drm, obj, 0);
>> +
>> +       return obj;
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_root_object_alloc);
>> +
>>   /**
>>    * drm_gpuvm_init() - initialize a &drm_gpuvm
>>    * @gpuvm: pointer to the &drm_gpuvm to initialize
>> + * @r_obj: the root &drm_gem_object providing the GPUVM's common
>> &dma_resv
>>    * @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
>> @@ -668,7 +715,7 @@ drm_gpuvm_range_valid(struct drm_gpuvm *gpuvm,
>>    * &name is expected to be managed by the surrounding driver
>> structures.
>>    */
>>   void
>> -drm_gpuvm_init(struct drm_gpuvm *gpuvm,
>> +drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct drm_gem_object
>> *r_obj,
>>                 const char *name,
>>                 u64 start_offset, u64 range,
>>                 u64 reserve_offset, u64 reserve_range,
>> @@ -683,6 +730,9 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm,
>>   
>>          gpuvm->name = name ? name : "unknown";
>>          gpuvm->ops = ops;
>> +       gpuvm->r_obj = r_obj;
>> +
>> +       drm_gem_object_get(r_obj);
>>   
>>          memset(&gpuvm->kernel_alloc_node, 0, sizeof(struct
>> drm_gpuva));
>>   
>> @@ -713,7 +763,9 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
>>                  __drm_gpuva_remove(&gpuvm->kernel_alloc_node);
>>   
>>          WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
>> -            "GPUVA tree is not empty, potentially leaking memory.");
>> +            "GPUVA tree is not empty, potentially leaking
>> memory.\n");
> 
> Should we cache the drm device in struct drm_gpuvm and use drm_warn()
> here instead of WARN?

I'd guess the additional backtrace of WARN() isn't overly useful in this
case. However, it might be a bit more obvious in dmesg due to its
verboseness. Not a strong opinion on that, though.

> 
>> +
>> +       drm_gem_object_put(gpuvm->r_obj);
>>   }
>>   EXPORT_SYMBOL_GPL(drm_gpuvm_destroy);
>>   
>> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>> b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>> index 5cf892c50f43..4dea847ef989 100644
>> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>> @@ -1808,8 +1808,9 @@ int
>>   nouveau_uvmm_init(struct nouveau_uvmm *uvmm, struct nouveau_cli
>> *cli,
>>                    u64 kernel_managed_addr, u64 kernel_managed_size)
>>   {
>> -       int ret;
>> +       struct drm_gem_object *r_obj;
>>          u64 kernel_managed_end = kernel_managed_addr +
>> kernel_managed_size;
>> +       int ret;
>>   
>>          mutex_init(&uvmm->mutex);
>>          dma_resv_init(&uvmm->resv);
>> @@ -1833,14 +1834,22 @@ nouveau_uvmm_init(struct nouveau_uvmm *uvmm,
>> struct nouveau_cli *cli,
>>                  goto out_unlock;
>>          }
>>   
>> +       r_obj = drm_gpuvm_root_object_alloc(cli->drm->dev);
>> +       if (!r_obj) {
>> +               ret = -ENOMEM;
>> +               goto out_unlock;
>> +       }
>> +
>>          uvmm->kernel_managed_addr = kernel_managed_addr;
>>          uvmm->kernel_managed_size = kernel_managed_size;
>>   
>> -       drm_gpuvm_init(&uvmm->base, cli->name,
>> +       drm_gpuvm_init(&uvmm->base, r_obj, cli->name,
>>                         NOUVEAU_VA_SPACE_START,
>>                         NOUVEAU_VA_SPACE_END,
>>                         kernel_managed_addr, kernel_managed_size,
>>                         NULL);
>> +       /* GPUVM takes care from here on. */
>> +       drm_gem_object_put(r_obj);
>>   
>>          ret = nvif_vmm_ctor(&cli->mmu, "uvmm",
>>                              cli->vmm.vmm.object.oclass, RAW,
>> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
>> index c7ed6bf441d4..0aec14d8b259 100644
>> --- a/include/drm/drm_gpuvm.h
>> +++ b/include/drm/drm_gpuvm.h
>> @@ -238,9 +238,15 @@ struct drm_gpuvm {
>>           * @ops: &drm_gpuvm_ops providing the split/merge steps to
>> drivers
>>           */
>>          const struct drm_gpuvm_ops *ops;
>> +
>> +       /**
>> +        * @r_obj: Root GEM object; representing the GPUVM's common
>> &dma_resv.
>> +        */
>> +       struct drm_gem_object *r_obj;
>>   };
>>   
>> -void drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name,
>> +void drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct drm_gem_object
>> *r_obj,
>> +                   const char *name,
>>                      u64 start_offset, u64 range,
>>                      u64 reserve_offset, u64 reserve_range,
>>                      const struct drm_gpuvm_ops *ops);
>> @@ -248,6 +254,33 @@ void drm_gpuvm_destroy(struct drm_gpuvm *gpuvm);
>>   
>>   bool drm_gpuvm_interval_empty(struct drm_gpuvm *gpuvm, u64 addr, u64
>> range);
>>   
>> +struct drm_gem_object *
>> +drm_gpuvm_root_object_alloc(struct drm_device *drm);
>> +
>> +/**
>> + * drm_gpuvm_resv() - returns the &drm_gpuvm's &dma_resv
>> + * @gpuvm__: the &drm_gpuvm
>> + *
>> + * Returns: a pointer to the &drm_gpuvm's shared &dma_resv
>> + */
>> +#define drm_gpuvm_resv(gpuvm__) ((gpuvm__)->r_obj->resv)
>> +
>> +/**
>> + * drm_gpuvm_resv_obj() - returns the &drm_gem_object holding the
>> &drm_gpuvm's
>> + * &dma_resv
>> + * @gpuvm__: the &drm_gpuvm
>> + *
>> + * Returns: a pointer to the &drm_gem_object holding the
>> &drm_gpuvm's shared
>> + * &dma_resv
>> + */
>> +#define drm_gpuvm_resv_obj(gpuvm__) ((gpuvm__)->r_obj)
>> +
>> +#define drm_gpuvm_resv_held(gpuvm__) \
>> +       dma_resv_held(drm_gpuvm_resv(gpuvm__))
>> +
>> +#define drm_gpuvm_resv_assert_held(gpuvm__) \
>> +       dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
>> +
>>   static inline struct drm_gpuva *
>>   __drm_gpuva_next(struct drm_gpuva *va)
>>   {
> 
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> 
>
  

On Fri, 2023-10-13 at 13:51 +0200, Danilo Krummrich wrote:
> On 10/13/23 13:38, Thomas Hellström wrote:
> > On Mon, 2023-10-09 at 01:32 +0200, Danilo Krummrich wrote:
> > > Provide a common dma-resv for GEM objects not being used outside
> > > of
> > > this
> > > GPU-VM. This is used in a subsequent patch to generalize dma-
> > > resv,
> > > external and evicted object handling and GEM validation.
> > > 
> > > Signed-off-by: Danilo Krummrich <dakr@redhat.com>
> > > ---
> > >   drivers/gpu/drm/drm_gpuvm.c            | 56
> > > +++++++++++++++++++++++++-
> > >   drivers/gpu/drm/nouveau/nouveau_uvmm.c | 13 +++++-
> > >   include/drm/drm_gpuvm.h                | 35 +++++++++++++++-
> > >   3 files changed, 99 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_gpuvm.c
> > > b/drivers/gpu/drm/drm_gpuvm.c
> > > index 02ecb45a2544..ebda9d594165 100644
> > > --- a/drivers/gpu/drm/drm_gpuvm.c
> > > +++ b/drivers/gpu/drm/drm_gpuvm.c
> > > @@ -61,6 +61,15 @@
> > >    * 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.
> > > + *
> > > + * &drm_gem_objects which are private to a single VM can share a
> > > common
> > > + * &dma_resv in order to improve locking efficiency (e.g. with
> > > &drm_exec).
> > > + * For this purpose drivers must pass a &drm_gem_object to
> > > drm_gpuvm_init(), in
> > > + * the following called 'root object', which serves as the
> > > container
> > 
> > Nit: Perhaps resv object altough it might typically be the root
> > page-
> > table object, that doesn't have any meaning to drm_gpuvm, which
> > uses it
> > solely as a container for the resv?
> 
> With "root" I didn't want to refer to the object representing the
> root
> page-table object, but being *the* object every other (internal)
> object
> needs to keep a reference to.

OK, yes but the reason they need a reference is because of the shared
resv, so IMO resv_object is a good fit. (I later noticed there's even
the function name drm_gpuvm_resv_obj()). And it will probably get
confused with the driver's "root" page table object, but up to you.

>  Maybe I should be more explicit here and say
> that drivers need to make sure every internal object requires a
> reference
> to take a reference to this root object.
> 
> > 
> > > of the
> > > + * GPUVM's shared &dma_resv. This root object can be a driver
> > > specific
> > > + * &drm_gem_object, such as the &drm_gem_object containing the
> > > root
> > > page table,
> > > + * but it can also be a 'dummy' object, which can be allocated
> > > with
> > > + * drm_gpuvm_root_object_alloc().
> > >    */
> > >   
> > >   /**
> > > @@ -652,9 +661,47 @@ drm_gpuvm_range_valid(struct drm_gpuvm
> > > *gpuvm,
> > >                 !drm_gpuvm_in_kernel_node(gpuvm, addr, range);
> > >   }
> > >   
> > > +static void
> > > +drm_gpuvm_gem_object_free(struct drm_gem_object *obj)
> > > +{
> > > +       drm_gem_object_release(obj);
> > > +       kfree(obj);
> > > +}
> > > +
> > > +static const struct drm_gem_object_funcs drm_gpuvm_object_funcs
> > > = {
> > > +       .free = drm_gpuvm_gem_object_free,
> > > +};
> > > +
> > > +/**
> > > + * drm_gpuvm_root_object_alloc() - allocate a dummy
> > > &drm_gem_object
> > > + * @drm: the drivers &drm_device
> > > + *
> > > + * Allocates a dummy &drm_gem_object which can be passed to
> > > drm_gpuvm_init() in
> > > + * order to serve as root GEM object providing the &drm_resv
> > > shared
> > > across
> > > + * &drm_gem_objects local to a single GPUVM.
> > > + *
> > > + * Returns: the &drm_gem_object on success, NULL on failure
> > > + */
> > > +struct drm_gem_object *
> > > +drm_gpuvm_root_object_alloc(struct drm_device *drm)
> > > +{
> > > +       struct drm_gem_object *obj;
> > > +
> > > +       obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> > > +       if (!obj)
> > > +               return NULL;
> > > +
> > > +       obj->funcs = &drm_gpuvm_object_funcs;
> > > +       drm_gem_private_object_init(drm, obj, 0);
> > > +
> > > +       return obj;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gpuvm_root_object_alloc);
> > > +
> > >   /**
> > >    * drm_gpuvm_init() - initialize a &drm_gpuvm
> > >    * @gpuvm: pointer to the &drm_gpuvm to initialize
> > > + * @r_obj: the root &drm_gem_object providing the GPUVM's common
> > > &dma_resv
> > >    * @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
> > > @@ -668,7 +715,7 @@ drm_gpuvm_range_valid(struct drm_gpuvm
> > > *gpuvm,
> > >    * &name is expected to be managed by the surrounding driver
> > > structures.
> > >    */
> > >   void
> > > -drm_gpuvm_init(struct drm_gpuvm *gpuvm,
> > > +drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct drm_gem_object
> > > *r_obj,
> > >                 const char *name,
> > >                 u64 start_offset, u64 range,
> > >                 u64 reserve_offset, u64 reserve_range,
> > > @@ -683,6 +730,9 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm,
> > >   
> > >          gpuvm->name = name ? name : "unknown";
> > >          gpuvm->ops = ops;
> > > +       gpuvm->r_obj = r_obj;
> > > +
> > > +       drm_gem_object_get(r_obj);
> > >   
> > >          memset(&gpuvm->kernel_alloc_node, 0, sizeof(struct
> > > drm_gpuva));
> > >   
> > > @@ -713,7 +763,9 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
> > >                  __drm_gpuva_remove(&gpuvm->kernel_alloc_node);
> > >   
> > >          WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
> > > -            "GPUVA tree is not empty, potentially leaking
> > > memory.");
> > > +            "GPUVA tree is not empty, potentially leaking
> > > memory.\n");
> > 
> > Should we cache the drm device in struct drm_gpuvm and use
> > drm_warn()
> > here instead of WARN?
> 
> I'd guess the additional backtrace of WARN() isn't overly useful in
> this
> case. However, it might be a bit more obvious in dmesg due to its
> verboseness. Not a strong opinion on that, though.

My bad. I meant drm_WARN(). In a multi-gpu environment it's nice to
have the extra device info.

/Thomas


> 
> > 
> > > +
> > > +       drm_gem_object_put(gpuvm->r_obj);
> > >   }
> > >   EXPORT_SYMBOL_GPL(drm_gpuvm_destroy);
> > >   
> > > diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> > > b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> > > index 5cf892c50f43..4dea847ef989 100644
> > > --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> > > +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> > > @@ -1808,8 +1808,9 @@ int
> > >   nouveau_uvmm_init(struct nouveau_uvmm *uvmm, struct nouveau_cli
> > > *cli,
> > >                    u64 kernel_managed_addr, u64
> > > kernel_managed_size)
> > >   {
> > > -       int ret;
> > > +       struct drm_gem_object *r_obj;
> > >          u64 kernel_managed_end = kernel_managed_addr +
> > > kernel_managed_size;
> > > +       int ret;
> > >   
> > >          mutex_init(&uvmm->mutex);
> > >          dma_resv_init(&uvmm->resv);
> > > @@ -1833,14 +1834,22 @@ nouveau_uvmm_init(struct nouveau_uvmm
> > > *uvmm,
> > > struct nouveau_cli *cli,
> > >                  goto out_unlock;
> > >          }
> > >   
> > > +       r_obj = drm_gpuvm_root_object_alloc(cli->drm->dev);
> > > +       if (!r_obj) {
> > > +               ret = -ENOMEM;
> > > +               goto out_unlock;
> > > +       }
> > > +
> > >          uvmm->kernel_managed_addr = kernel_managed_addr;
> > >          uvmm->kernel_managed_size = kernel_managed_size;
> > >   
> > > -       drm_gpuvm_init(&uvmm->base, cli->name,
> > > +       drm_gpuvm_init(&uvmm->base, r_obj, cli->name,
> > >                         NOUVEAU_VA_SPACE_START,
> > >                         NOUVEAU_VA_SPACE_END,
> > >                         kernel_managed_addr, kernel_managed_size,
> > >                         NULL);
> > > +       /* GPUVM takes care from here on. */
> > > +       drm_gem_object_put(r_obj);
> > >   
> > >          ret = nvif_vmm_ctor(&cli->mmu, "uvmm",
> > >                              cli->vmm.vmm.object.oclass, RAW,
> > > diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
> > > index c7ed6bf441d4..0aec14d8b259 100644
> > > --- a/include/drm/drm_gpuvm.h
> > > +++ b/include/drm/drm_gpuvm.h
> > > @@ -238,9 +238,15 @@ struct drm_gpuvm {
> > >           * @ops: &drm_gpuvm_ops providing the split/merge steps
> > > to
> > > drivers
> > >           */
> > >          const struct drm_gpuvm_ops *ops;
> > > +
> > > +       /**
> > > +        * @r_obj: Root GEM object; representing the GPUVM's
> > > common
> > > &dma_resv.
> > > +        */
> > > +       struct drm_gem_object *r_obj;
> > >   };
> > >   
> > > -void drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name,
> > > +void drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct
> > > drm_gem_object
> > > *r_obj,
> > > +                   const char *name,
> > >                      u64 start_offset, u64 range,
> > >                      u64 reserve_offset, u64 reserve_range,
> > >                      const struct drm_gpuvm_ops *ops);
> > > @@ -248,6 +254,33 @@ void drm_gpuvm_destroy(struct drm_gpuvm
> > > *gpuvm);
> > >   
> > >   bool drm_gpuvm_interval_empty(struct drm_gpuvm *gpuvm, u64
> > > addr, u64
> > > range);
> > >   
> > > +struct drm_gem_object *
> > > +drm_gpuvm_root_object_alloc(struct drm_device *drm);
> > > +
> > > +/**
> > > + * drm_gpuvm_resv() - returns the &drm_gpuvm's &dma_resv
> > > + * @gpuvm__: the &drm_gpuvm
> > > + *
> > > + * Returns: a pointer to the &drm_gpuvm's shared &dma_resv
> > > + */
> > > +#define drm_gpuvm_resv(gpuvm__) ((gpuvm__)->r_obj->resv)
> > > +
> > > +/**
> > > + * drm_gpuvm_resv_obj() - returns the &drm_gem_object holding
> > > the
> > > &drm_gpuvm's
> > > + * &dma_resv
> > > + * @gpuvm__: the &drm_gpuvm
> > > + *
> > > + * Returns: a pointer to the &drm_gem_object holding the
> > > &drm_gpuvm's shared
> > > + * &dma_resv
> > > + */
> > > +#define drm_gpuvm_resv_obj(gpuvm__) ((gpuvm__)->r_obj)
> > > +
> > > +#define drm_gpuvm_resv_held(gpuvm__) \
> > > +       dma_resv_held(drm_gpuvm_resv(gpuvm__))
> > > +
> > > +#define drm_gpuvm_resv_assert_held(gpuvm__) \
> > > +       dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
> > > +
> > >   static inline struct drm_gpuva *
> > >   __drm_gpuva_next(struct drm_gpuva *va)
> > >   {
> > 
> > Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > 
> > 
>
  

On 10/13/23 15:00, Thomas Hellström wrote:
> On Fri, 2023-10-13 at 13:51 +0200, Danilo Krummrich wrote:
>> On 10/13/23 13:38, Thomas Hellström wrote:
>>> On Mon, 2023-10-09 at 01:32 +0200, Danilo Krummrich wrote:
>>>> Provide a common dma-resv for GEM objects not being used outside
>>>> of
>>>> this
>>>> GPU-VM. This is used in a subsequent patch to generalize dma-
>>>> resv,
>>>> external and evicted object handling and GEM validation.
>>>>
>>>> Signed-off-by: Danilo Krummrich <dakr@redhat.com>
>>>> ---
>>>>    drivers/gpu/drm/drm_gpuvm.c            | 56
>>>> +++++++++++++++++++++++++-
>>>>    drivers/gpu/drm/nouveau/nouveau_uvmm.c | 13 +++++-
>>>>    include/drm/drm_gpuvm.h                | 35 +++++++++++++++-
>>>>    3 files changed, 99 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_gpuvm.c
>>>> b/drivers/gpu/drm/drm_gpuvm.c
>>>> index 02ecb45a2544..ebda9d594165 100644
>>>> --- a/drivers/gpu/drm/drm_gpuvm.c
>>>> +++ b/drivers/gpu/drm/drm_gpuvm.c
>>>> @@ -61,6 +61,15 @@
>>>>     * 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.
>>>> + *
>>>> + * &drm_gem_objects which are private to a single VM can share a
>>>> common
>>>> + * &dma_resv in order to improve locking efficiency (e.g. with
>>>> &drm_exec).
>>>> + * For this purpose drivers must pass a &drm_gem_object to
>>>> drm_gpuvm_init(), in
>>>> + * the following called 'root object', which serves as the
>>>> container
>>>
>>> Nit: Perhaps resv object altough it might typically be the root
>>> page-
>>> table object, that doesn't have any meaning to drm_gpuvm, which
>>> uses it
>>> solely as a container for the resv?
>>
>> With "root" I didn't want to refer to the object representing the
>> root
>> page-table object, but being *the* object every other (internal)
>> object
>> needs to keep a reference to.
> 
> OK, yes but the reason they need a reference is because of the shared
> resv, so IMO resv_object is a good fit. (I later noticed there's even
> the function name drm_gpuvm_resv_obj()). And it will probably get
> confused with the driver's "root" page table object, but up to you.

Yeah, maybe 'resv object' is better, gonna change it.

> 
>>   Maybe I should be more explicit here and say
>> that drivers need to make sure every internal object requires a
>> reference
>> to take a reference to this root object.
>>
>>>
>>>> of the
>>>> + * GPUVM's shared &dma_resv. This root object can be a driver
>>>> specific
>>>> + * &drm_gem_object, such as the &drm_gem_object containing the
>>>> root
>>>> page table,
>>>> + * but it can also be a 'dummy' object, which can be allocated
>>>> with
>>>> + * drm_gpuvm_root_object_alloc().
>>>>     */
>>>>    
>>>>    /**
>>>> @@ -652,9 +661,47 @@ drm_gpuvm_range_valid(struct drm_gpuvm
>>>> *gpuvm,
>>>>                  !drm_gpuvm_in_kernel_node(gpuvm, addr, range);
>>>>    }
>>>>    
>>>> +static void
>>>> +drm_gpuvm_gem_object_free(struct drm_gem_object *obj)
>>>> +{
>>>> +       drm_gem_object_release(obj);
>>>> +       kfree(obj);
>>>> +}
>>>> +
>>>> +static const struct drm_gem_object_funcs drm_gpuvm_object_funcs
>>>> = {
>>>> +       .free = drm_gpuvm_gem_object_free,
>>>> +};
>>>> +
>>>> +/**
>>>> + * drm_gpuvm_root_object_alloc() - allocate a dummy
>>>> &drm_gem_object
>>>> + * @drm: the drivers &drm_device
>>>> + *
>>>> + * Allocates a dummy &drm_gem_object which can be passed to
>>>> drm_gpuvm_init() in
>>>> + * order to serve as root GEM object providing the &drm_resv
>>>> shared
>>>> across
>>>> + * &drm_gem_objects local to a single GPUVM.
>>>> + *
>>>> + * Returns: the &drm_gem_object on success, NULL on failure
>>>> + */
>>>> +struct drm_gem_object *
>>>> +drm_gpuvm_root_object_alloc(struct drm_device *drm)
>>>> +{
>>>> +       struct drm_gem_object *obj;
>>>> +
>>>> +       obj = kzalloc(sizeof(*obj), GFP_KERNEL);
>>>> +       if (!obj)
>>>> +               return NULL;
>>>> +
>>>> +       obj->funcs = &drm_gpuvm_object_funcs;
>>>> +       drm_gem_private_object_init(drm, obj, 0);
>>>> +
>>>> +       return obj;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_root_object_alloc);
>>>> +
>>>>    /**
>>>>     * drm_gpuvm_init() - initialize a &drm_gpuvm
>>>>     * @gpuvm: pointer to the &drm_gpuvm to initialize
>>>> + * @r_obj: the root &drm_gem_object providing the GPUVM's common
>>>> &dma_resv
>>>>     * @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
>>>> @@ -668,7 +715,7 @@ drm_gpuvm_range_valid(struct drm_gpuvm
>>>> *gpuvm,
>>>>     * &name is expected to be managed by the surrounding driver
>>>> structures.
>>>>     */
>>>>    void
>>>> -drm_gpuvm_init(struct drm_gpuvm *gpuvm,
>>>> +drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct drm_gem_object
>>>> *r_obj,
>>>>                  const char *name,
>>>>                  u64 start_offset, u64 range,
>>>>                  u64 reserve_offset, u64 reserve_range,
>>>> @@ -683,6 +730,9 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm,
>>>>    
>>>>           gpuvm->name = name ? name : "unknown";
>>>>           gpuvm->ops = ops;
>>>> +       gpuvm->r_obj = r_obj;
>>>> +
>>>> +       drm_gem_object_get(r_obj);
>>>>    
>>>>           memset(&gpuvm->kernel_alloc_node, 0, sizeof(struct
>>>> drm_gpuva));
>>>>    
>>>> @@ -713,7 +763,9 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
>>>>                   __drm_gpuva_remove(&gpuvm->kernel_alloc_node);
>>>>    
>>>>           WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
>>>> -            "GPUVA tree is not empty, potentially leaking
>>>> memory.");
>>>> +            "GPUVA tree is not empty, potentially leaking
>>>> memory.\n");
>>>
>>> Should we cache the drm device in struct drm_gpuvm and use
>>> drm_warn()
>>> here instead of WARN?
>>
>> I'd guess the additional backtrace of WARN() isn't overly useful in
>> this
>> case. However, it might be a bit more obvious in dmesg due to its
>> verboseness. Not a strong opinion on that, though.
> 
> My bad. I meant drm_WARN(). In a multi-gpu environment it's nice to
> have the extra device info.

Sure, gonna add a separate patch to change that in all places.

> 
> /Thomas
> 
> 
>>
>>>
>>>> +
>>>> +       drm_gem_object_put(gpuvm->r_obj);
>>>>    }
>>>>    EXPORT_SYMBOL_GPL(drm_gpuvm_destroy);
>>>>    
>>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>>>> b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>>>> index 5cf892c50f43..4dea847ef989 100644
>>>> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>>>> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
>>>> @@ -1808,8 +1808,9 @@ int
>>>>    nouveau_uvmm_init(struct nouveau_uvmm *uvmm, struct nouveau_cli
>>>> *cli,
>>>>                     u64 kernel_managed_addr, u64
>>>> kernel_managed_size)
>>>>    {
>>>> -       int ret;
>>>> +       struct drm_gem_object *r_obj;
>>>>           u64 kernel_managed_end = kernel_managed_addr +
>>>> kernel_managed_size;
>>>> +       int ret;
>>>>    
>>>>           mutex_init(&uvmm->mutex);
>>>>           dma_resv_init(&uvmm->resv);
>>>> @@ -1833,14 +1834,22 @@ nouveau_uvmm_init(struct nouveau_uvmm
>>>> *uvmm,
>>>> struct nouveau_cli *cli,
>>>>                   goto out_unlock;
>>>>           }
>>>>    
>>>> +       r_obj = drm_gpuvm_root_object_alloc(cli->drm->dev);
>>>> +       if (!r_obj) {
>>>> +               ret = -ENOMEM;
>>>> +               goto out_unlock;
>>>> +       }
>>>> +
>>>>           uvmm->kernel_managed_addr = kernel_managed_addr;
>>>>           uvmm->kernel_managed_size = kernel_managed_size;
>>>>    
>>>> -       drm_gpuvm_init(&uvmm->base, cli->name,
>>>> +       drm_gpuvm_init(&uvmm->base, r_obj, cli->name,
>>>>                          NOUVEAU_VA_SPACE_START,
>>>>                          NOUVEAU_VA_SPACE_END,
>>>>                          kernel_managed_addr, kernel_managed_size,
>>>>                          NULL);
>>>> +       /* GPUVM takes care from here on. */
>>>> +       drm_gem_object_put(r_obj);
>>>>    
>>>>           ret = nvif_vmm_ctor(&cli->mmu, "uvmm",
>>>>                               cli->vmm.vmm.object.oclass, RAW,
>>>> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
>>>> index c7ed6bf441d4..0aec14d8b259 100644
>>>> --- a/include/drm/drm_gpuvm.h
>>>> +++ b/include/drm/drm_gpuvm.h
>>>> @@ -238,9 +238,15 @@ struct drm_gpuvm {
>>>>            * @ops: &drm_gpuvm_ops providing the split/merge steps
>>>> to
>>>> drivers
>>>>            */
>>>>           const struct drm_gpuvm_ops *ops;
>>>> +
>>>> +       /**
>>>> +        * @r_obj: Root GEM object; representing the GPUVM's
>>>> common
>>>> &dma_resv.
>>>> +        */
>>>> +       struct drm_gem_object *r_obj;
>>>>    };
>>>>    
>>>> -void drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name,
>>>> +void drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct
>>>> drm_gem_object
>>>> *r_obj,
>>>> +                   const char *name,
>>>>                       u64 start_offset, u64 range,
>>>>                       u64 reserve_offset, u64 reserve_range,
>>>>                       const struct drm_gpuvm_ops *ops);
>>>> @@ -248,6 +254,33 @@ void drm_gpuvm_destroy(struct drm_gpuvm
>>>> *gpuvm);
>>>>    
>>>>    bool drm_gpuvm_interval_empty(struct drm_gpuvm *gpuvm, u64
>>>> addr, u64
>>>> range);
>>>>    
>>>> +struct drm_gem_object *
>>>> +drm_gpuvm_root_object_alloc(struct drm_device *drm);
>>>> +
>>>> +/**
>>>> + * drm_gpuvm_resv() - returns the &drm_gpuvm's &dma_resv
>>>> + * @gpuvm__: the &drm_gpuvm
>>>> + *
>>>> + * Returns: a pointer to the &drm_gpuvm's shared &dma_resv
>>>> + */
>>>> +#define drm_gpuvm_resv(gpuvm__) ((gpuvm__)->r_obj->resv)
>>>> +
>>>> +/**
>>>> + * drm_gpuvm_resv_obj() - returns the &drm_gem_object holding
>>>> the
>>>> &drm_gpuvm's
>>>> + * &dma_resv
>>>> + * @gpuvm__: the &drm_gpuvm
>>>> + *
>>>> + * Returns: a pointer to the &drm_gem_object holding the
>>>> &drm_gpuvm's shared
>>>> + * &dma_resv
>>>> + */
>>>> +#define drm_gpuvm_resv_obj(gpuvm__) ((gpuvm__)->r_obj)
>>>> +
>>>> +#define drm_gpuvm_resv_held(gpuvm__) \
>>>> +       dma_resv_held(drm_gpuvm_resv(gpuvm__))
>>>> +
>>>> +#define drm_gpuvm_resv_assert_held(gpuvm__) \
>>>> +       dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
>>>> +
>>>>    static inline struct drm_gpuva *
>>>>    __drm_gpuva_next(struct drm_gpuva *va)
>>>>    {
>>>
>>> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>>>
>>>
>>
>