Re: [Intel-gfx] [RFC v4 03/14] drm/i915/vm_bind: Expose i915_gem_object_max_page_size()

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 21/09/2022 19:00, Niranjana Vishwanathapura wrote:
> On Wed, Sep 21, 2022 at 10:13:12AM +0100, Tvrtko Ursulin wrote:
>>
>> On 21/09/2022 08:09, Niranjana Vishwanathapura wrote:
>>> Expose i915_gem_object_max_page_size() function non-static
>>> which will be used by the vm_bind feature.
>>>
>>> Signed-off-by: Niranjana Vishwanathapura 
>>> <niranjana.vishwanathapura@intel.com>
>>> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/gem/i915_gem_create.c | 20 +++++++++++++++-----
>>>  drivers/gpu/drm/i915/gem/i915_gem_object.h |  2 ++
>>>  2 files changed, 17 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_create.c 
>>> b/drivers/gpu/drm/i915/gem/i915_gem_create.c
>>> index 33673fe7ee0a..3b3ab4abb0a3 100644
>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_create.c
>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_create.c
>>> @@ -11,14 +11,24 @@
>>>  #include "pxp/intel_pxp.h"
>>>  #include "i915_drv.h"
>>> +#include "i915_gem_context.h"
>>
>> I can't spot that you are adding any code which would need this? 
>> I915_GTT_PAGE_SIZE_4K? It is in intel_gtt.h.
> 
> This include should have been added in a later patch for calling
> i915_gem_vm_lookup(). But got added here while patch refactoring.
> Will fix.
> 
>>
>>>  #include "i915_gem_create.h"
>>>  #include "i915_trace.h"
>>>  #include "i915_user_extensions.h"
>>> -static u32 object_max_page_size(struct intel_memory_region 
>>> **placements,
>>> -                unsigned int n_placements)
>>> +/**
>>> + * i915_gem_object_max_page_size() - max of min_page_size of the 
>>> regions
>>> + * @placements:  list of regions
>>> + * @n_placements: number of the placements
>>> + *
>>> + * Calculates the max of the min_page_size of a list of placements 
>>> passed in.
>>> + *
>>> + * Return: max of the min_page_size
>>> + */
>>> +u32 i915_gem_object_max_page_size(struct intel_memory_region 
>>> **placements,
>>> +                  unsigned int n_placements)
>>>  {
>>> -    u32 max_page_size = 0;
>>> +    u32 max_page_size = I915_GTT_PAGE_SIZE_4K;
>>>      int i;
>>>      for (i = 0; i < n_placements; i++) {
>>> @@ -28,7 +38,6 @@ static u32 object_max_page_size(struct 
>>> intel_memory_region **placements,
>>>          max_page_size = max_t(u32, max_page_size, mr->min_page_size);
>>>      }
>>> -    GEM_BUG_ON(!max_page_size);
>>>      return max_page_size;
>>>  }
>>> @@ -99,7 +108,8 @@ __i915_gem_object_create_user_ext(struct 
>>> drm_i915_private *i915, u64 size,
>>>      i915_gem_flush_free_objects(i915);
>>> -    size = round_up(size, object_max_page_size(placements, 
>>> n_placements));
>>> +    size = round_up(size, i915_gem_object_max_page_size(placements,
>>> +                                n_placements));
>>>      if (size == 0)
>>>          return ERR_PTR(-EINVAL);
>>
>> Because of the changes above this path is now unreachable. I suppose 
>> it was meant to tell the user "you have supplied no placements"? But 
>> then GEM_BUG_ON (which you remove) used to be wrong.
>>
> 
> Yah, looks like an existing problem. May be this "size == 0" check
> should have been made before we do the round_up()? ie., check input 'size'
> paramter is not 0?
> I think for now, I will remove this check as it was unreachable anyhow.

Hm that's true as well. i915_gem_create_ext_ioctl ensures at least one 
placement and internal callers do as well.

To be safe, instead of removing maybe move to before "size = " and 
change to "if (GEM_WARN_ON(n_placements == 0))"? Not sure.. Matt any 
thoughts here given the changes in this patch?

Regards,

Tvrtko

> 
> Niranjana
> 
>> Regards,
>>
>> Tvrtko
>>
>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h 
>>> b/drivers/gpu/drm/i915/gem/i915_gem_object.h
>>> index 7317d4102955..8c97bddad921 100644
>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
>>> @@ -47,6 +47,8 @@ static inline bool i915_gem_object_size_2big(u64 size)
>>>  }
>>>  void i915_gem_init__objects(struct drm_i915_private *i915);
>>> +u32 i915_gem_object_max_page_size(struct intel_memory_region 
>>> **placements,
>>> +                  unsigned int n_placements);
>>>  void i915_objects_module_exit(void);
>>>  int i915_objects_module_init(void);