On gen8 and onwards, we can mark GPU accesses through the ppGTT as being
read-only, that is cause any GPU write onto that page to be discarded
(not triggering a fault). This is all that we need to finally support
the read-only flag for userptr!
Testcase: igt/gem_userptr_blits/readonly*
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Jon Bloomfield <jon.bloomfi...@intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.william.a...@gmail.com>
Reviewed-by: Jon Bloomfield <jon.bloomfi...@intel.com>
---
drivers/gpu/drm/i915/i915_gem_object.h | 1 -
drivers/gpu/drm/i915/i915_gem_userptr.c | 15 +++++++++------
2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_object.h
b/drivers/gpu/drm/i915/i915_gem_object.h
index 56e9f00d2c4c..83e5e01fa9ea 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -267,7 +267,6 @@ struct drm_i915_gem_object {
union {
struct i915_gem_userptr {
uintptr_t ptr;
- unsigned read_only :1;
struct i915_mm_struct *mm;
struct i915_mmu_object *mmu_object;
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c
b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 854bd51b9478..045db5ef17ac 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -507,7 +507,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct
*_work)
struct mm_struct *mm = obj->userptr.mm->mm;
unsigned int flags = 0;
- if (!obj->userptr.read_only)
+ if (!i915_gem_object_is_readonly(obj))
flags |= FOLL_WRITE;
ret = -EFAULT;
@@ -643,7 +643,7 @@ static int i915_gem_userptr_get_pages(struct
drm_i915_gem_object *obj)
if (pvec) /* defer to worker if malloc fails */
pinned = __get_user_pages_fast(obj->userptr.ptr,
num_pages,
- !obj->userptr.read_only,
+
!i915_gem_object_is_readonly(obj),
pvec);
}
@@ -789,10 +789,12 @@ i915_gem_userptr_ioctl(struct drm_device *dev,
return -EFAULT;
if (args->flags & I915_USERPTR_READ_ONLY) {
- /* On almost all of the current hw, we cannot tell the GPU that
a
- * page is readonly, so this is just a placeholder in the uAPI.
+ /*
+ * On almost all of the older hw, we cannot tell the GPU that
+ * a page is readonly.
*/
- return -ENODEV;
+ if (INTEL_GEN(dev_priv) < 8 || !USES_PPGTT(dev_priv))
+ return -ENODEV;
}
obj = i915_gem_object_alloc(dev_priv);
@@ -806,7 +808,8 @@ i915_gem_userptr_ioctl(struct drm_device *dev,
i915_gem_object_set_cache_coherency(obj, I915_CACHE_LLC);
obj->userptr.ptr = args->user_ptr;
- obj->userptr.read_only = !!(args->flags & I915_USERPTR_READ_ONLY);
+ if (args->flags & I915_USERPTR_READ_ONLY)
+ i915_gem_object_set_readonly(obj);
/* And keep a pointer to the current->mm for resolving the user pages
* at binding. This means that we need to hook into the mmu_notifier
--
2.18.0
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