diff mbox series

[v2,1/5] drm/i915/gem: Implement object migration

Message ID 20210628090943.45690-2-thomas.hellstrom@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series drm/i915/gem: Introduce a migrate interface | expand

Commit Message

Thomas Hellström June 28, 2021, 9:09 a.m. UTC
Introduce an interface to migrate objects between regions.
This is primarily intended to migrate objects to LMEM for display and
to SYSTEM for dma-buf, but might be reused in one form or another for
performande-based migration.

v2:
- Verify that the memory region given as an id really exists.
  (Reported by Matthew Auld)
- Call i915_gem_object_{init,release}_memory_region() when switching region
  to handle also switching region lists. (Reported by Matthew Auld)

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.c    | 96 +++++++++++++++++++
 drivers/gpu/drm/i915/gem/i915_gem_object.h    | 12 +++
 .../gpu/drm/i915/gem/i915_gem_object_types.h  |  9 ++
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c       | 69 +++++++++----
 drivers/gpu/drm/i915/gem/i915_gem_wait.c      | 19 ++++
 5 files changed, 188 insertions(+), 17 deletions(-)

Comments

Thomas Hellström June 28, 2021, 9:47 a.m. UTC | #1
On 6/28/21 11:09 AM, Thomas Hellström wrote:
> Introduce an interface to migrate objects between regions.
> This is primarily intended to migrate objects to LMEM for display and
> to SYSTEM for dma-buf, but might be reused in one form or another for
> performande-based migration.
>
> v2:
> - Verify that the memory region given as an id really exists.
>    (Reported by Matthew Auld)
> - Call i915_gem_object_{init,release}_memory_region() when switching region
>    to handle also switching region lists. (Reported by Matthew Auld)
>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_object.c    | 96 +++++++++++++++++++
>   drivers/gpu/drm/i915/gem/i915_gem_object.h    | 12 +++
>   .../gpu/drm/i915/gem/i915_gem_object_types.h  |  9 ++
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c       | 69 +++++++++----
>   drivers/gpu/drm/i915/gem/i915_gem_wait.c      | 19 ++++
>   5 files changed, 188 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> index 07e8ff9a8aae..52a37619054d 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> @@ -513,6 +513,102 @@ bool i915_gem_object_has_iomem(const struct drm_i915_gem_object *obj)
>   	return obj->mem_flags & I915_BO_FLAG_IOMEM;
>   }
>   
> +/**
> + * i915_gem_object_can_migrate - Whether an object likely can be migrated
> + *
> + * @obj: The object to migrate
> + * @id: The region intended to migrate to
> + *
> + * Check whether the object backend supports migration to the
> + * given region. Note that pinning may affect the ability to migrate.
> + *
> + * Return: true if migration is possible, false otherwise.
> + */
> +bool i915_gem_object_can_migrate(struct drm_i915_gem_object *obj,
> +				 enum intel_region_id id)
> +{
> +	struct drm_i915_private *i915 = to_i915(obj->base.dev);
> +	unsigned int num_allowed = obj->mm.n_placements;
> +	struct intel_memory_region *mr;
> +	unsigned int i;
> +
> +	GEM_BUG_ON(id >= INTEL_REGION_UNKNOWN);
> +	GEM_BUG_ON(obj->mm.madv != I915_MADV_WILLNEED);
> +
> +	if (!obj->ops->migrate)
> +		return false;
> +
> +	mr = i915->mm.regions[id];
> +	if (!mr)
> +		return false;


Hmm. Should probably switch order between these two, otherwise 
can_migrate will always return false on !TTM

/Thomas
kernel test robot June 28, 2021, 11:28 a.m. UTC | #2
Hi "Thomas,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm-tip/drm-tip]
[cannot apply to drm-intel/for-linux-next drm-exynos/exynos-drm-next tegra-drm/drm/tegra/for-next drm/drm-next v5.13 next-20210625]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Thomas-Hellstr-m/drm-i915-gem-Introduce-a-migrate-interface/20210628-171204
base:   git://anongit.freedesktop.org/drm/drm-tip drm-tip
config: i386-randconfig-a014-20210628 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/e4e5a7f5c031252f26c868a2aa17a031a1558336
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Thomas-Hellstr-m/drm-i915-gem-Introduce-a-migrate-interface/20210628-171204
        git checkout e4e5a7f5c031252f26c868a2aa17a031a1558336
        # save the attached .config to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/gpu/drm/i915/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/i915/gem/i915_gem_wait.c:184: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * Waits for rendering to the object to be completed
>> drivers/gpu/drm/i915/gem/i915_gem_wait.c:307: warning: expecting prototype for i915_gem_object_wait_migrate(). Prototype was for i915_gem_object_wait_migration() instead


vim +307 drivers/gpu/drm/i915/gem/i915_gem_wait.c

   293	
   294	/**
   295	 * i915_gem_object_wait_migrate - Sync an accelerated migration operation
   296	 * @obj: The migrating object.
   297	 * @flags: waiting flags. Currently supports only I915_WAIT_INTERRUPTIBLE.
   298	 *
   299	 * Wait for any pending async migration operation on the object,
   300	 * whether it's explicitly (i915_gem_object_migrate()) or implicitly
   301	 * (swapin, initial clearing) initiated.
   302	 *
   303	 * Return: 0 if successful, -ERESTARTSYS if a signal was hit during waiting.
   304	 */
   305	int i915_gem_object_wait_migration(struct drm_i915_gem_object *obj,
   306					   unsigned int flags)
 > 307	{

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot June 28, 2021, 12:54 p.m. UTC | #3
Hi "Thomas,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm-tip/drm-tip]
[cannot apply to drm-intel/for-linux-next drm-exynos/exynos-drm-next tegra-drm/drm/tegra/for-next drm/drm-next v5.13 next-20210628]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Thomas-Hellstr-m/drm-i915-gem-Introduce-a-migrate-interface/20210628-171204
base:   git://anongit.freedesktop.org/drm/drm-tip drm-tip
config: x86_64-randconfig-a003-20210628 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 4c92e31dd0f1bd152eda883af20ff7fbcaa14945)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/e4e5a7f5c031252f26c868a2aa17a031a1558336
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Thomas-Hellstr-m/drm-i915-gem-Introduce-a-migrate-interface/20210628-171204
        git checkout e4e5a7f5c031252f26c868a2aa17a031a1558336
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/gpu/drm/i915/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/i915/gem/i915_gem_wait.c:184: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * Waits for rendering to the object to be completed
>> drivers/gpu/drm/i915/gem/i915_gem_wait.c:307: warning: expecting prototype for i915_gem_object_wait_migrate(). Prototype was for i915_gem_object_wait_migration() instead


vim +307 drivers/gpu/drm/i915/gem/i915_gem_wait.c

   182	
   183	/**
 > 184	 * Waits for rendering to the object to be completed
   185	 * @obj: i915 gem object
   186	 * @flags: how to wait (under a lock, for all rendering or just for writes etc)
   187	 * @timeout: how long to wait
   188	 */
   189	int
   190	i915_gem_object_wait(struct drm_i915_gem_object *obj,
   191			     unsigned int flags,
   192			     long timeout)
   193	{
   194		might_sleep();
   195		GEM_BUG_ON(timeout < 0);
   196	
   197		timeout = i915_gem_object_wait_reservation(obj->base.resv,
   198							   flags, timeout);
   199		return timeout < 0 ? timeout : 0;
   200	}
   201	
   202	static inline unsigned long nsecs_to_jiffies_timeout(const u64 n)
   203	{
   204		/* nsecs_to_jiffies64() does not guard against overflow */
   205		if (NSEC_PER_SEC % HZ &&
   206		    div_u64(n, NSEC_PER_SEC) >= MAX_JIFFY_OFFSET / HZ)
   207			return MAX_JIFFY_OFFSET;
   208	
   209		return min_t(u64, MAX_JIFFY_OFFSET, nsecs_to_jiffies64(n) + 1);
   210	}
   211	
   212	static unsigned long to_wait_timeout(s64 timeout_ns)
   213	{
   214		if (timeout_ns < 0)
   215			return MAX_SCHEDULE_TIMEOUT;
   216	
   217		if (timeout_ns == 0)
   218			return 0;
   219	
   220		return nsecs_to_jiffies_timeout(timeout_ns);
   221	}
   222	
   223	/**
   224	 * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
   225	 * @dev: drm device pointer
   226	 * @data: ioctl data blob
   227	 * @file: drm file pointer
   228	 *
   229	 * Returns 0 if successful, else an error is returned with the remaining time in
   230	 * the timeout parameter.
   231	 *  -ETIME: object is still busy after timeout
   232	 *  -ERESTARTSYS: signal interrupted the wait
   233	 *  -ENONENT: object doesn't exist
   234	 * Also possible, but rare:
   235	 *  -EAGAIN: incomplete, restart syscall
   236	 *  -ENOMEM: damn
   237	 *  -ENODEV: Internal IRQ fail
   238	 *  -E?: The add request failed
   239	 *
   240	 * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
   241	 * non-zero timeout parameter the wait ioctl will wait for the given number of
   242	 * nanoseconds on an object becoming unbusy. Since the wait itself does so
   243	 * without holding struct_mutex the object may become re-busied before this
   244	 * function completes. A similar but shorter * race condition exists in the busy
   245	 * ioctl
   246	 */
   247	int
   248	i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
   249	{
   250		struct drm_i915_gem_wait *args = data;
   251		struct drm_i915_gem_object *obj;
   252		ktime_t start;
   253		long ret;
   254	
   255		if (args->flags != 0)
   256			return -EINVAL;
   257	
   258		obj = i915_gem_object_lookup(file, args->bo_handle);
   259		if (!obj)
   260			return -ENOENT;
   261	
   262		start = ktime_get();
   263	
   264		ret = i915_gem_object_wait(obj,
   265					   I915_WAIT_INTERRUPTIBLE |
   266					   I915_WAIT_PRIORITY |
   267					   I915_WAIT_ALL,
   268					   to_wait_timeout(args->timeout_ns));
   269	
   270		if (args->timeout_ns > 0) {
   271			args->timeout_ns -= ktime_to_ns(ktime_sub(ktime_get(), start));
   272			if (args->timeout_ns < 0)
   273				args->timeout_ns = 0;
   274	
   275			/*
   276			 * Apparently ktime isn't accurate enough and occasionally has a
   277			 * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch
   278			 * things up to make the test happy. We allow up to 1 jiffy.
   279			 *
   280			 * This is a regression from the timespec->ktime conversion.
   281			 */
   282			if (ret == -ETIME && !nsecs_to_jiffies(args->timeout_ns))
   283				args->timeout_ns = 0;
   284	
   285			/* Asked to wait beyond the jiffie/scheduler precision? */
   286			if (ret == -ETIME && args->timeout_ns)
   287				ret = -EAGAIN;
   288		}
   289	
   290		i915_gem_object_put(obj);
   291		return ret;
   292	}
   293	
   294	/**
   295	 * i915_gem_object_wait_migrate - Sync an accelerated migration operation
   296	 * @obj: The migrating object.
   297	 * @flags: waiting flags. Currently supports only I915_WAIT_INTERRUPTIBLE.
   298	 *
   299	 * Wait for any pending async migration operation on the object,
   300	 * whether it's explicitly (i915_gem_object_migrate()) or implicitly
   301	 * (swapin, initial clearing) initiated.
   302	 *
   303	 * Return: 0 if successful, -ERESTARTSYS if a signal was hit during waiting.
   304	 */
   305	int i915_gem_object_wait_migration(struct drm_i915_gem_object *obj,
   306					   unsigned int flags)
 > 307	{

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 07e8ff9a8aae..52a37619054d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -513,6 +513,102 @@  bool i915_gem_object_has_iomem(const struct drm_i915_gem_object *obj)
 	return obj->mem_flags & I915_BO_FLAG_IOMEM;
 }
 
+/**
+ * i915_gem_object_can_migrate - Whether an object likely can be migrated
+ *
+ * @obj: The object to migrate
+ * @id: The region intended to migrate to
+ *
+ * Check whether the object backend supports migration to the
+ * given region. Note that pinning may affect the ability to migrate.
+ *
+ * Return: true if migration is possible, false otherwise.
+ */
+bool i915_gem_object_can_migrate(struct drm_i915_gem_object *obj,
+				 enum intel_region_id id)
+{
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
+	unsigned int num_allowed = obj->mm.n_placements;
+	struct intel_memory_region *mr;
+	unsigned int i;
+
+	GEM_BUG_ON(id >= INTEL_REGION_UNKNOWN);
+	GEM_BUG_ON(obj->mm.madv != I915_MADV_WILLNEED);
+
+	if (!obj->ops->migrate)
+		return false;
+
+	mr = i915->mm.regions[id];
+	if (!mr)
+		return false;
+
+	if (obj->mm.region == mr)
+		return true;
+
+	if (!i915_gem_object_evictable(obj))
+		return false;
+
+	if (!(obj->flags & I915_BO_ALLOC_USER))
+		return true;
+
+	if (num_allowed == 0)
+		return false;
+
+	for (i = 0; i < num_allowed; ++i) {
+		if (mr == obj->mm.placements[i])
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * i915_gem_object_migrate - Migrate an object to the desired region id
+ * @obj: The object to migrate.
+ * @ww: An optional struct i915_gem_ww_ctx. If NULL, the backend may
+ * not be successful in evicting other objects to make room for this object.
+ * @id: The region id to migrate to.
+ *
+ * Attempt to migrate the object to the desired memory region. The
+ * object backend must support migration and the object may not be
+ * pinned, (explicitly pinned pages or pinned vmas). The object must
+ * be locked.
+ * On successful completion, the object will have pages pointing to
+ * memory in the new region, but an async migration task may not have
+ * completed yet, and to accomplish that, i915_gem_object_wait_migration()
+ * must be called.
+ *
+ * Return: 0 on success. Negative error code on failure. In particular may
+ * return -ENXIO on lack of region space, -EDEADLK for deadlock avoidance
+ * if @ww is set, -EINTR or -ERESTARTSYS if signal pending, and
+ * -EBUSY if the object is pinned.
+ */
+int i915_gem_object_migrate(struct drm_i915_gem_object *obj,
+			    struct i915_gem_ww_ctx *ww,
+			    enum intel_region_id id)
+{
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
+	struct intel_memory_region *mr;
+
+	GEM_BUG_ON(id >= INTEL_REGION_UNKNOWN);
+	GEM_BUG_ON(obj->mm.madv != I915_MADV_WILLNEED);
+	assert_object_held(obj);
+
+	mr = i915->mm.regions[id];
+	GEM_BUG_ON(!mr);
+
+	if (obj->mm.region == mr)
+		return 0;
+
+	if (!i915_gem_object_evictable(obj))
+		return -EBUSY;
+
+	if (!obj->ops->migrate)
+		return -EOPNOTSUPP;
+
+	return obj->ops->migrate(obj, mr);
+}
+
 void i915_gem_init__objects(struct drm_i915_private *i915)
 {
 	INIT_WORK(&i915->mm.free_work, __i915_gem_free_work);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index ea3224a480c4..8cbd7a5334e2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -17,6 +17,8 @@ 
 #include "i915_gem_ww.h"
 #include "i915_vma_types.h"
 
+enum intel_region_id;
+
 /*
  * XXX: There is a prevalence of the assumption that we fit the
  * object's page count inside a 32bit _signed_ variable. Let's document
@@ -597,6 +599,16 @@  bool i915_gem_object_migratable(struct drm_i915_gem_object *obj);
 
 bool i915_gem_object_validates_to_lmem(struct drm_i915_gem_object *obj);
 
+int i915_gem_object_migrate(struct drm_i915_gem_object *obj,
+			    struct i915_gem_ww_ctx *ww,
+			    enum intel_region_id id);
+
+bool i915_gem_object_can_migrate(struct drm_i915_gem_object *obj,
+				 enum intel_region_id id);
+
+int i915_gem_object_wait_migration(struct drm_i915_gem_object *obj,
+				   unsigned int flags);
+
 #ifdef CONFIG_MMU_NOTIFIER
 static inline bool
 i915_gem_object_is_userptr(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 441f913c87e6..ef3de2ae9723 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -18,6 +18,7 @@ 
 
 struct drm_i915_gem_object;
 struct intel_fronbuffer;
+struct intel_memory_region;
 
 /*
  * struct i915_lut_handle tracks the fast lookups from handle to vma used
@@ -77,6 +78,14 @@  struct drm_i915_gem_object_ops {
 	 * delayed_free - Override the default delayed free implementation
 	 */
 	void (*delayed_free)(struct drm_i915_gem_object *obj);
+
+	/**
+	 * migrate - Migrate object to a different region either for
+	 * pinning or for as long as the object lock is held.
+	 */
+	int (*migrate)(struct drm_i915_gem_object *obj,
+		       struct intel_memory_region *mr);
+
 	void (*release)(struct drm_i915_gem_object *obj);
 
 	const struct vm_operations_struct *mmap_ops;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index c39d982c4fa6..8f89185b6507 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -617,7 +617,8 @@  struct ttm_device_funcs *i915_ttm_driver(void)
 	return &i915_ttm_bo_driver;
 }
 
-static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
+static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
+				struct ttm_placement *placement)
 {
 	struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
 	struct ttm_operation_ctx ctx = {
@@ -625,19 +626,12 @@  static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
 		.no_wait_gpu = false,
 	};
 	struct sg_table *st;
-	struct ttm_place requested, busy[I915_TTM_MAX_PLACEMENTS];
-	struct ttm_placement placement;
 	int real_num_busy;
 	int ret;
 
-	GEM_BUG_ON(obj->mm.n_placements > I915_TTM_MAX_PLACEMENTS);
-
-	/* Move to the requested placement. */
-	i915_ttm_placement_from_obj(obj, &requested, busy, &placement);
-
 	/* First try only the requested placement. No eviction. */
-	real_num_busy = fetch_and_zero(&placement.num_busy_placement);
-	ret = ttm_bo_validate(bo, &placement, &ctx);
+	real_num_busy = fetch_and_zero(&placement->num_busy_placement);
+	ret = ttm_bo_validate(bo, placement, &ctx);
 	if (ret) {
 		ret = i915_ttm_err_to_gem(ret);
 		/*
@@ -652,8 +646,8 @@  static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
 		 * If the initial attempt fails, allow all accepted placements,
 		 * evicting if necessary.
 		 */
-		placement.num_busy_placement = real_num_busy;
-		ret = ttm_bo_validate(bo, &placement, &ctx);
+		placement->num_busy_placement = real_num_busy;
+		ret = ttm_bo_validate(bo, placement, &ctx);
 		if (ret)
 			return i915_ttm_err_to_gem(ret);
 	}
@@ -668,16 +662,56 @@  static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
 		i915_ttm_adjust_gem_after_move(obj);
 	}
 
-	/* Object either has a page vector or is an iomem object */
-	st = bo->ttm ? i915_ttm_tt_get_st(bo->ttm) : obj->ttm.cached_io_st;
-	if (IS_ERR(st))
-		return PTR_ERR(st);
+	if (!obj->mm.pages) {
+		/* Object either has a page vector or is an iomem object */
+		st = bo->ttm ? i915_ttm_tt_get_st(bo->ttm) : obj->ttm.cached_io_st;
+		if (IS_ERR(st))
+			return PTR_ERR(st);
 
-	__i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl));
+		__i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl));
+	}
 
 	return ret;
 }
 
+static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
+{
+	struct ttm_place requested, busy[I915_TTM_MAX_PLACEMENTS];
+	struct ttm_placement placement;
+
+	GEM_BUG_ON(obj->mm.n_placements > I915_TTM_MAX_PLACEMENTS);
+
+	/* Move to the requested placement. */
+	i915_ttm_placement_from_obj(obj, &requested, busy, &placement);
+
+	return __i915_ttm_get_pages(obj, &placement);
+}
+
+static int i915_ttm_migrate(struct drm_i915_gem_object *obj,
+			    struct intel_memory_region *mr)
+{
+	struct ttm_place requested;
+	struct ttm_placement placement;
+	int ret;
+
+	i915_ttm_place_from_region(mr, &requested, obj->flags);
+	placement.num_placement = 1;
+	placement.num_busy_placement = 1;
+	placement.placement = &requested;
+	placement.busy_placement = &requested;
+
+	ret = __i915_ttm_get_pages(obj, &placement);
+	if (ret)
+		return ret;
+
+	if (obj->mm.region != mr) {
+		i915_gem_object_release_memory_region(obj);
+		i915_gem_object_init_memory_region(obj, mr);
+	}
+
+	return 0;
+}
+
 static void i915_ttm_put_pages(struct drm_i915_gem_object *obj,
 			       struct sg_table *st)
 {
@@ -814,6 +848,7 @@  static const struct drm_i915_gem_object_ops i915_gem_ttm_obj_ops = {
 	.truncate = i915_ttm_purge,
 	.adjust_lru = i915_ttm_adjust_lru,
 	.delayed_free = i915_ttm_delayed_free,
+	.migrate = i915_ttm_migrate,
 	.mmap_offset = i915_ttm_mmap_offset,
 	.mmap_ops = &vm_ops_ttm,
 };
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index 1070d3afdce7..e9f7a8d9f0e2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -290,3 +290,22 @@  i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	i915_gem_object_put(obj);
 	return ret;
 }
+
+/**
+ * i915_gem_object_wait_migrate - Sync an accelerated migration operation
+ * @obj: The migrating object.
+ * @flags: waiting flags. Currently supports only I915_WAIT_INTERRUPTIBLE.
+ *
+ * Wait for any pending async migration operation on the object,
+ * whether it's explicitly (i915_gem_object_migrate()) or implicitly
+ * (swapin, initial clearing) initiated.
+ *
+ * Return: 0 if successful, -ERESTARTSYS if a signal was hit during waiting.
+ */
+int i915_gem_object_wait_migration(struct drm_i915_gem_object *obj,
+				   unsigned int flags)
+{
+	might_sleep();
+	/* NOP for now. */
+	return 0;
+}