On 22/09/2022 17:18, 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.vishwanathap...@intel.com>
Signed-off-by: Andi Shyti <andi.sh...@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.

Oh yeah sneaky round up.. Thanks, my bad.

Regards,

Tvrtko

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