drm/i915: Do not define vma on stack

Defining vma on stack can cause stack overflow, if
vma gets populated with new fields.

v2:
 (Daniel Vetter)
  - Add kerneldoc for new field

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>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210916162819.27848-2-matthew.brost@intel.com

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 3a16d08608a544c55ba56714fe01d24cbb52b124..f632dbd32b42d9eb2d53856dfd96f8897e6953a4 100644 (file)
--- 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 99bb1fe1af6686d01386e0c96f5aaa74416f7c85..1e00bf65639e77c020b48ba6a525ba8896c1c175 100644 (file)
--- 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 +76,14 @@ struct intel_uc_fw {
        bool user_overridden;
        size_t size;
        struct drm_i915_gem_object *obj;
+       /**
+        * @dummy: A vma used in binding the uc fw to ggtt. We can't define this
+        * vma on the stack as it can lead to a stack overflow, so we define it
+        * here. Safe to have 1 copy per uc fw because the binding is single
+        * threaded as it done during driver load (inherently single threaded)
+        * or during a GT reset (mutex guarantees single threaded).
+        */
+       struct i915_vma dummy;
 
        /*
         * The firmware build process will generate a version header file with major and