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

[Niranjana Vishwanathapura]

On Thu, Sep 22, 2022 at 05:18:28PM +0100, Matthew Auld wrote:
>On 22/09/2022 09:09, Tvrtko Ursulin wrote:
>>
>>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 at intel.com>
>>>>>Signed-off-by: Andi Shyti <andi.shyti at 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?
>
>The check is also to reject a zero sized object with args->size = 0, 
>i.e round_up(0, PAGE_SIZE) == 0. So for sure that is still needed 
>here.

Thanks Matt.
Yah, we could check for "size == 0" before we round_up, but doing it
after like here should be just fine. Will keep it as is.

Niranjana

>
>>
>>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);