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Commit 0b100760 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/userptr: Enable read-only support on gen8+ 



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!

v2: Check default address space for read only support as a proxy for the
user context/ppgtt.

Testcase: igt/gem_userptr_blits/readonly*
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.william.auld@gmail.com>
Reviewed-by: default avatarJon Bloomfield <jon.bloomfield@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712191430.9269-1-chris@chris-wilson.co.uk
parent f8c1cce3

drivers/gpu/drm/i915/i915_gem_object.h

+0 −1
Original line number Diff line number Diff line
@@ -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;

drivers/gpu/drm/i915/i915_gem_userptr.c

+12 −6
Original line number Diff line number Diff line
@@ -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);

	}
@@ -789,9 +789,14 @@ 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.

		struct i915_hw_ppgtt *ppgtt;



		/*

		 * On almost all of the older hw, we cannot tell the GPU that

		 * a page is readonly.

		 */

		ppgtt = dev_priv->kernel_context->ppgtt;

		if (!ppgtt || !ppgtt->vm.has_read_only)

			return -ENODEV;

	}
@@ -806,7 +811,8 @@ 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