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

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

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.

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);