Re: [Intel-gfx] [PATCH 1/4] drm/i915: Do not define vma on stack

[Matthew Brost <matthew.brost@intel.com>]

On Mon, Aug 02, 2021 at 10:11:18PM -0700, Matthew Brost wrote:
> From: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
> 
> Defining vma on stack can cause stack overflow, if
> vma gets populated with new fields.
> 
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Signed-off-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
> Signef-off-by: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 18 +++++++++---------
>  drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h |  2 ++
>  2 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> index 3a16d08608a5..f632dbd32b42 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> @@ -413,20 +413,20 @@ static void uc_fw_bind_ggtt(struct intel_uc_fw *uc_fw)
>  {
>  	struct drm_i915_gem_object *obj = uc_fw->obj;
>  	struct i915_ggtt *ggtt = __uc_fw_to_gt(uc_fw)->ggtt;
> -	struct i915_vma dummy = {
> -		.node.start = uc_fw_ggtt_offset(uc_fw),
> -		.node.size = obj->base.size,
> -		.pages = obj->mm.pages,
> -		.vm = &ggtt->vm,
> -	};
> +	struct i915_vma *dummy = &uc_fw->dummy;
> +
> +	dummy->node.start = uc_fw_ggtt_offset(uc_fw);
> +	dummy->node.size = obj->base.size;
> +	dummy->pages = obj->mm.pages;
> +	dummy->vm = &ggtt->vm;
>  
>  	GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
> -	GEM_BUG_ON(dummy.node.size > ggtt->uc_fw.size);
> +	GEM_BUG_ON(dummy->node.size > ggtt->uc_fw.size);
>  
>  	/* uc_fw->obj cache domains were not controlled across suspend */
> -	drm_clflush_sg(dummy.pages);
> +	drm_clflush_sg(dummy->pages);
>  
> -	ggtt->vm.insert_entries(&ggtt->vm, &dummy, I915_CACHE_NONE, 0);
> +	ggtt->vm.insert_entries(&ggtt->vm, dummy, I915_CACHE_NONE, 0);
>  }
>  
>  static void uc_fw_unbind_ggtt(struct intel_uc_fw *uc_fw)
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h
> index 99bb1fe1af66..693cc0ebcd63 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h
> @@ -10,6 +10,7 @@
>  #include "intel_uc_fw_abi.h"
>  #include "intel_device_info.h"
>  #include "i915_gem.h"
> +#include "i915_vma.h"
>  
>  struct drm_printer;
>  struct drm_i915_private;
> @@ -75,6 +76,7 @@ struct intel_uc_fw {
>  	bool user_overridden;
>  	size_t size;
>  	struct drm_i915_gem_object *obj;
> +	struct i915_vma dummy;
>  
>  	/*
>  	 * The firmware build process will generate a version header file with major and
> -- 
> 2.28.0
>