On Wed, Jun 18, 2025 at 04:21:22PM +0530, Ghimiray, Himal Prasad wrote:
> 
> 
> On 18-06-2025 14:56, Thomas Hellström wrote:
> > From: Matthew Brost <matthew.br...@intel.com>
> > 
> > The migration functionality and track-keeping of per-pagemap VRAM
> > mapped to the CPU mm is not per GPU_vm, but rather per pagemap.
> > This is also reflected by the functions not needing the drm_gpusvm
> > structures. So move to drm_pagemap.
> > 
> > With this, drm_gpusvm shouldn't really access the page zone-device-data
> > since its meaning is internal to drm_pagemap. Currently it's used to
> > reject mapping ranges backed by multiple drm_pagemap allocations.
> > For now, make the zone-device-data a void pointer.
> > 
> > Alter the interface of drm_gpusvm_migrate_to_devmem() to ensure we don't
> > pass a gpusvm pointer.
> > 
> > Rename CONFIG_DRM_XE_DEVMEM_MIRROR to CONFIG_DRM_XE_PAGEMAP.
> > 
> > Matt is listed as author of this commit since he wrote most of the code,
> > and it makes sense to retain his git authorship.
> > Thomas mostly moved the code around.
> > 
> > v3:
> > - Kerneldoc fixes (CI)
> > - Don't update documentation about how the drm_pagemap
> >    migration should be interpreted until upcoming
> >    patches where the functionality is implemented.
> >    (Matt Brost)
> > v4:
> > - More kerneldoc fixes around timeslice_ms
> >    (Himal Ghimiray, Matt Brost)
> > 
> > Co-developed-by: Thomas Hellström <thomas.hellst...@linux.intel.com>
> > Signed-off-by: Thomas Hellström <thomas.hellst...@linux.intel.com>

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

> > ---
> >   Documentation/gpu/rfc/gpusvm.rst     |  12 +-
> >   drivers/gpu/drm/Makefile             |   6 +-
> >   drivers/gpu/drm/drm_gpusvm.c         | 760 +------------------------
> >   drivers/gpu/drm/drm_pagemap.c        | 794 +++++++++++++++++++++++++++
> >   drivers/gpu/drm/xe/Kconfig           |  10 +-
> >   drivers/gpu/drm/xe/xe_bo_types.h     |   2 +-
> >   drivers/gpu/drm/xe/xe_device_types.h |   2 +-
> >   drivers/gpu/drm/xe/xe_svm.c          |  47 +-
> >   include/drm/drm_gpusvm.h             |  96 ----
> >   include/drm/drm_pagemap.h            | 101 ++++
> >   10 files changed, 957 insertions(+), 873 deletions(-)
> >   create mode 100644 drivers/gpu/drm/drm_pagemap.c
> > 
> > diff --git a/Documentation/gpu/rfc/gpusvm.rst 
> > b/Documentation/gpu/rfc/gpusvm.rst
> > index bcf66a8137a6..469db1372f16 100644
> > --- a/Documentation/gpu/rfc/gpusvm.rst
> > +++ b/Documentation/gpu/rfc/gpusvm.rst
> > @@ -73,15 +73,21 @@ Overview of baseline design
> >   .. kernel-doc:: drivers/gpu/drm/drm_gpusvm.c
> >      :doc: Locking
> > -.. kernel-doc:: drivers/gpu/drm/drm_gpusvm.c
> > -   :doc: Migration
> > -
> >   .. kernel-doc:: drivers/gpu/drm/drm_gpusvm.c
> >      :doc: Partial Unmapping of Ranges
> >   .. kernel-doc:: drivers/gpu/drm/drm_gpusvm.c
> >      :doc: Examples
> > +Overview of drm_pagemap design
> > +==============================
> > +
> > +.. kernel-doc:: drivers/gpu/drm/drm_pagemap.c
> > +   :doc: Overview
> > +
> > +.. kernel-doc:: drivers/gpu/drm/drm_pagemap.c
> > +   :doc: Migration
> > +
> >   Possible future design features
> >   ===============================
> > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> > index 5050ac32bba2..4dafbdc8f86a 100644
> > --- a/drivers/gpu/drm/Makefile
> > +++ b/drivers/gpu/drm/Makefile
> > @@ -104,7 +104,11 @@ obj-$(CONFIG_DRM_PANEL_BACKLIGHT_QUIRKS) += 
> > drm_panel_backlight_quirks.o
> >   #
> >   obj-$(CONFIG_DRM_EXEC) += drm_exec.o
> >   obj-$(CONFIG_DRM_GPUVM) += drm_gpuvm.o
> > -obj-$(CONFIG_DRM_GPUSVM) += drm_gpusvm.o
> > +
> > +drm_gpusvm_helper-y := \
> > +   drm_gpusvm.o\
> > +   drm_pagemap.o
> > +obj-$(CONFIG_DRM_GPUSVM) += drm_gpusvm_helper.o
> >   obj-$(CONFIG_DRM_BUDDY) += drm_buddy.o
> > diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
> > index 7ff81aa0a1ca..6e2c155a6969 100644
> > --- a/drivers/gpu/drm/drm_gpusvm.c
> > +++ b/drivers/gpu/drm/drm_gpusvm.c
> > @@ -8,10 +8,9 @@
> >   #include <linux/dma-mapping.h>
> >   #include <linux/hmm.h>
> > +#include <linux/hugetlb_inline.h>
> >   #include <linux/memremap.h>
> > -#include <linux/migrate.h>
> >   #include <linux/mm_types.h>
> > -#include <linux/pagemap.h>
> >   #include <linux/slab.h>
> >   #include <drm/drm_device.h>
> > @@ -107,21 +106,6 @@
> >    * to add annotations to GPU SVM.
> >    */
> > -/**
> > - * DOC: Migration
> > - *
> > - * The migration support is quite simple, allowing migration between RAM 
> > and
> > - * device memory at the range granularity. For example, GPU SVM currently 
> > does
> > - * not support mixing RAM and device memory pages within a range. This 
> > means
> > - * that upon GPU fault, the entire range can be migrated to device memory, 
> > and
> > - * upon CPU fault, the entire range is migrated to RAM. Mixed RAM and 
> > device
> > - * memory storage within a range could be added in the future if required.
> > - *
> > - * The reasoning for only supporting range granularity is as follows: it
> > - * simplifies the implementation, and range sizes are driver-defined and 
> > should
> > - * be relatively small.
> > - */
> > -
> >   /**
> >    * DOC: Partial Unmapping of Ranges
> >    *
> > @@ -193,10 +177,10 @@
> >    *                if (driver_migration_policy(range)) {
> >    *                        mmap_read_lock(mm);
> >    *                        devmem = driver_alloc_devmem();
> > - *                 err = drm_gpusvm_migrate_to_devmem(gpusvm, range,
> > - *                                                    devmem_allocation,
> > - *                                                    &ctx);
> > - *                 mmap_read_unlock(mm);
> > + *                 err = drm_pagemap_migrate_to_devmem(devmem, gpusvm->mm, 
> > gpuva_start,
> > + *                                                          gpuva_end, 
> > ctx->timeslice_ms,
> > + *                                                          
> > driver_pgmap_owner());
> > + *                      mmap_read_unlock(mm);
> >    *                        if (err)        // CPU mappings may have changed
> >    *                                goto retry;
> >    *                }
> > @@ -288,97 +272,6 @@ npages_in_range(unsigned long start, unsigned long end)
> >     return (end - start) >> PAGE_SHIFT;
> >   }
> > -/**
> > - * struct drm_gpusvm_zdd - GPU SVM zone device data
> > - *
> > - * @refcount: Reference count for the zdd
> > - * @devmem_allocation: device memory allocation
> > - * @device_private_page_owner: Device private pages owner
> > - *
> > - * This structure serves as a generic wrapper installed in
> > - * page->zone_device_data. It provides infrastructure for looking up a 
> > device
> > - * memory allocation upon CPU page fault and asynchronously releasing 
> > device
> > - * memory once the CPU has no page references. Asynchronous release is 
> > useful
> > - * because CPU page references can be dropped in IRQ contexts, while 
> > releasing
> > - * device memory likely requires sleeping locks.
> > - */
> > -struct drm_gpusvm_zdd {
> > -   struct kref refcount;
> > -   struct drm_gpusvm_devmem *devmem_allocation;
> > -   void *device_private_page_owner;
> > -};
> > -
> > -/**
> > - * drm_gpusvm_zdd_alloc() - Allocate a zdd structure.
> > - * @device_private_page_owner: Device private pages owner
> > - *
> > - * This function allocates and initializes a new zdd structure. It sets up 
> > the
> > - * reference count and initializes the destroy work.
> > - *
> > - * Return: Pointer to the allocated zdd on success, ERR_PTR() on failure.
> > - */
> > -static struct drm_gpusvm_zdd *
> > -drm_gpusvm_zdd_alloc(void *device_private_page_owner)
> > -{
> > -   struct drm_gpusvm_zdd *zdd;
> > -
> > -   zdd = kmalloc(sizeof(*zdd), GFP_KERNEL);
> > -   if (!zdd)
> > -           return NULL;
> > -
> > -   kref_init(&zdd->refcount);
> > -   zdd->devmem_allocation = NULL;
> > -   zdd->device_private_page_owner = device_private_page_owner;
> > -
> > -   return zdd;
> > -}
> > -
> > -/**
> > - * drm_gpusvm_zdd_get() - Get a reference to a zdd structure.
> > - * @zdd: Pointer to the zdd structure.
> > - *
> > - * This function increments the reference count of the provided zdd 
> > structure.
> > - *
> > - * Return: Pointer to the zdd structure.
> > - */
> > -static struct drm_gpusvm_zdd *drm_gpusvm_zdd_get(struct drm_gpusvm_zdd 
> > *zdd)
> > -{
> > -   kref_get(&zdd->refcount);
> > -   return zdd;
> > -}
> > -
> > -/**
> > - * drm_gpusvm_zdd_destroy() - Destroy a zdd structure.
> > - * @ref: Pointer to the reference count structure.
> > - *
> > - * This function queues the destroy_work of the zdd for asynchronous 
> > destruction.
> > - */
> > -static void drm_gpusvm_zdd_destroy(struct kref *ref)
> > -{
> > -   struct drm_gpusvm_zdd *zdd =
> > -           container_of(ref, struct drm_gpusvm_zdd, refcount);
> > -   struct drm_gpusvm_devmem *devmem = zdd->devmem_allocation;
> > -
> > -   if (devmem) {
> > -           complete_all(&devmem->detached);
> > -           if (devmem->ops->devmem_release)
> > -                   devmem->ops->devmem_release(devmem);
> > -   }
> > -   kfree(zdd);
> > -}
> > -
> > -/**
> > - * drm_gpusvm_zdd_put() - Put a zdd reference.
> > - * @zdd: Pointer to the zdd structure.
> > - *
> > - * This function decrements the reference count of the provided zdd 
> > structure
> > - * and schedules its destruction if the count drops to zero.
> > - */
> > -static void drm_gpusvm_zdd_put(struct drm_gpusvm_zdd *zdd)
> > -{
> > -   kref_put(&zdd->refcount, drm_gpusvm_zdd_destroy);
> > -}
> > -
> >   /**
> >    * drm_gpusvm_range_find() - Find GPU SVM range from GPU SVM notifier
> >    * @notifier: Pointer to the GPU SVM notifier structure.
> > @@ -945,7 +838,7 @@ drm_gpusvm_range_chunk_size(struct drm_gpusvm *gpusvm,
> >              * process-many-malloc' fails. In the failure case, each process
> >              * mallocs 16k but the CPU VMA is ~128k which results in 64k SVM
> >              * ranges. When migrating the SVM ranges, some processes fail in
> > -            * drm_gpusvm_migrate_to_devmem with 'migrate.cpages != npages'
> > +            * drm_pagemap_migrate_to_devmem with 'migrate.cpages != npages'
> >              * and then upon drm_gpusvm_range_get_pages device pages from
> >              * other processes are collected + faulted in which creates all
> >              * sorts of problems. Unsure exactly how this happening, also
> > @@ -1363,7 +1256,7 @@ int drm_gpusvm_range_get_pages(struct drm_gpusvm 
> > *gpusvm,
> >             .dev_private_owner = gpusvm->device_private_page_owner,
> >     };
> >     struct mm_struct *mm = gpusvm->mm;
> > -   struct drm_gpusvm_zdd *zdd;
> > +   void *zdd;
> >     unsigned long timeout =
> >             jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
> >     unsigned long i, j;
> > @@ -1465,7 +1358,7 @@ int drm_gpusvm_range_get_pages(struct drm_gpusvm 
> > *gpusvm,
> >                             }
> >                             pagemap = page_pgmap(page);
> > -                           dpagemap = zdd->devmem_allocation->dpagemap;
> > +                           dpagemap = drm_pagemap_page_to_dpagemap(page);
> >                             if (drm_WARN_ON(gpusvm->drm, !dpagemap)) {
> >                                     /*
> >                                      * Raced. This is not supposed to happen
> > @@ -1489,7 +1382,7 @@ int drm_gpusvm_range_get_pages(struct drm_gpusvm 
> > *gpusvm,
> >             } else {
> >                     dma_addr_t addr;
> > -                   if (is_zone_device_page(page) || zdd) {
> > +                   if (is_zone_device_page(page) || pagemap) {
> >                             err = -EOPNOTSUPP;
> >                             goto err_unmap;
> >                     }
> > @@ -1517,7 +1410,7 @@ int drm_gpusvm_range_get_pages(struct drm_gpusvm 
> > *gpusvm,
> >             flags.has_dma_mapping = true;
> >     }
> > -   if (zdd) {
> > +   if (pagemap) {
> >             flags.has_devmem_pages = true;
> >             range->dpagemap = dpagemap;
> >     }
> > @@ -1545,6 +1438,7 @@ EXPORT_SYMBOL_GPL(drm_gpusvm_range_get_pages);
> >   /**
> >    * drm_gpusvm_range_unmap_pages() - Unmap pages associated with a GPU SVM 
> > range
> > + * drm_gpusvm_range_evict() - Evict GPU SVM range
> >    * @gpusvm: Pointer to the GPU SVM structure
> >    * @range: Pointer to the GPU SVM range structure
> >    * @ctx: GPU SVM context
> > @@ -1575,562 +1469,11 @@ void drm_gpusvm_range_unmap_pages(struct 
> > drm_gpusvm *gpusvm,
> >   EXPORT_SYMBOL_GPL(drm_gpusvm_range_unmap_pages);
> >   /**
> > - * drm_gpusvm_migration_unlock_put_page() - Put a migration page
> > - * @page: Pointer to the page to put
> > - *
> > - * This function unlocks and puts a page.
> > - */
> > -static void drm_gpusvm_migration_unlock_put_page(struct page *page)
> > -{
> > -   unlock_page(page);
> > -   put_page(page);
> > -}
> > -
> > -/**
> > - * drm_gpusvm_migration_unlock_put_pages() - Put migration pages
> > - * @npages: Number of pages
> > - * @migrate_pfn: Array of migrate page frame numbers
> > - *
> > - * This function unlocks and puts an array of pages.
> > - */
> > -static void drm_gpusvm_migration_unlock_put_pages(unsigned long npages,
> > -                                             unsigned long *migrate_pfn)
> > -{
> > -   unsigned long i;
> > -
> > -   for (i = 0; i < npages; ++i) {
> > -           struct page *page;
> > -
> > -           if (!migrate_pfn[i])
> > -                   continue;
> > -
> > -           page = migrate_pfn_to_page(migrate_pfn[i]);
> > -           drm_gpusvm_migration_unlock_put_page(page);
> > -           migrate_pfn[i] = 0;
> > -   }
> > -}
> > -
> > -/**
> > - * drm_gpusvm_get_devmem_page() - Get a reference to a device memory page
> > - * @page: Pointer to the page
> > - * @zdd: Pointer to the GPU SVM zone device data
> > - *
> > - * This function associates the given page with the specified GPU SVM zone
> > - * device data and initializes it for zone device usage.
> > - */
> > -static void drm_gpusvm_get_devmem_page(struct page *page,
> > -                                  struct drm_gpusvm_zdd *zdd)
> > -{
> > -   page->zone_device_data = drm_gpusvm_zdd_get(zdd);
> > -   zone_device_page_init(page);
> > -}
> > -
> > -/**
> > - * drm_gpusvm_migrate_map_pages() - Map migration pages for GPU SVM 
> > migration
> > - * @dev: The device for which the pages are being mapped
> > - * @dma_addr: Array to store DMA addresses corresponding to mapped pages
> > - * @migrate_pfn: Array of migrate page frame numbers to map
> > - * @npages: Number of pages to map
> > - * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
> > - *
> > - * This function maps pages of memory for migration usage in GPU SVM. It
> > - * iterates over each page frame number provided in @migrate_pfn, maps the
> > - * corresponding page, and stores the DMA address in the provided @dma_addr
> > - * array.
> > - *
> > - * Return: 0 on success, -EFAULT if an error occurs during mapping.
> > - */
> > -static int drm_gpusvm_migrate_map_pages(struct device *dev,
> > -                                   dma_addr_t *dma_addr,
> > -                                   unsigned long *migrate_pfn,
> > -                                   unsigned long npages,
> > -                                   enum dma_data_direction dir)
> > -{
> > -   unsigned long i;
> > -
> > -   for (i = 0; i < npages; ++i) {
> > -           struct page *page = migrate_pfn_to_page(migrate_pfn[i]);
> > -
> > -           if (!page)
> > -                   continue;
> > -
> > -           if (WARN_ON_ONCE(is_zone_device_page(page)))
> > -                   return -EFAULT;
> > -
> > -           dma_addr[i] = dma_map_page(dev, page, 0, PAGE_SIZE, dir);
> > -           if (dma_mapping_error(dev, dma_addr[i]))
> > -                   return -EFAULT;
> > -   }
> > -
> > -   return 0;
> > -}
> > -
> > -/**
> > - * drm_gpusvm_migrate_unmap_pages() - Unmap pages previously mapped for 
> > GPU SVM migration
> > - * @dev: The device for which the pages were mapped
> > - * @dma_addr: Array of DMA addresses corresponding to mapped pages
> > - * @npages: Number of pages to unmap
> > - * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
> > - *
> > - * This function unmaps previously mapped pages of memory for GPU Shared 
> > Virtual
> > - * Memory (SVM). It iterates over each DMA address provided in @dma_addr, 
> > checks
> > - * if it's valid and not already unmapped, and unmaps the corresponding 
> > page.
> > - */
> > -static void drm_gpusvm_migrate_unmap_pages(struct device *dev,
> > -                                      dma_addr_t *dma_addr,
> > -                                      unsigned long npages,
> > -                                      enum dma_data_direction dir)
> > -{
> > -   unsigned long i;
> > -
> > -   for (i = 0; i < npages; ++i) {
> > -           if (!dma_addr[i] || dma_mapping_error(dev, dma_addr[i]))
> > -                   continue;
> > -
> > -           dma_unmap_page(dev, dma_addr[i], PAGE_SIZE, dir);
> > -   }
> > -}
> > -
> > -/**
> > - * drm_gpusvm_migrate_to_devmem() - Migrate GPU SVM range to device memory
> > + * drm_gpusvm_range_evict() - Evict GPU SVM range
> >    * @gpusvm: Pointer to the GPU SVM structure
> > - * @range: Pointer to the GPU SVM range structure
> > - * @devmem_allocation: Pointer to the device memory allocation. The caller
> > - *                     should hold a reference to the device memory 
> > allocation,
> > - *                     which should be dropped via ops->devmem_release or 
> > upon
> > - *                     the failure of this function.
> > - * @ctx: GPU SVM context
> > - *
> > - * This function migrates the specified GPU SVM range to device memory. It
> > - * performs the necessary setup and invokes the driver-specific operations 
> > for
> > - * migration to device memory. Upon successful return, @devmem_allocation 
> > can
> > - * safely reference @range until ops->devmem_release is called which only 
> > upon
> > - * successful return. Expected to be called while holding the mmap lock in 
> > read
> > - * mode.
> > - *
> > - * Return: 0 on success, negative error code on failure.
> > - */
> > -int drm_gpusvm_migrate_to_devmem(struct drm_gpusvm *gpusvm,
> > -                            struct drm_gpusvm_range *range,
> > -                            struct drm_gpusvm_devmem *devmem_allocation,
> > -                            const struct drm_gpusvm_ctx *ctx)
> > -{
> > -   const struct drm_gpusvm_devmem_ops *ops = devmem_allocation->ops;
> > -   unsigned long start = drm_gpusvm_range_start(range),
> > -                 end = drm_gpusvm_range_end(range);
> > -   struct migrate_vma migrate = {
> > -           .start          = start,
> > -           .end            = end,
> > -           .pgmap_owner    = gpusvm->device_private_page_owner,
> > -           .flags          = MIGRATE_VMA_SELECT_SYSTEM,
> > -   };
> > -   struct mm_struct *mm = gpusvm->mm;
> > -   unsigned long i, npages = npages_in_range(start, end);
> > -   struct vm_area_struct *vas;
> > -   struct drm_gpusvm_zdd *zdd = NULL;
> > -   struct page **pages;
> > -   dma_addr_t *dma_addr;
> > -   void *buf;
> > -   int err;
> > -
> > -   mmap_assert_locked(gpusvm->mm);
> > -
> > -   if (!range->flags.migrate_devmem)
> > -           return -EINVAL;
> > -
> > -   if (!ops->populate_devmem_pfn || !ops->copy_to_devmem ||
> > -       !ops->copy_to_ram)
> > -           return -EOPNOTSUPP;
> > -
> > -   vas = vma_lookup(mm, start);
> > -   if (!vas) {
> > -           err = -ENOENT;
> > -           goto err_out;
> > -   }
> > -
> > -   if (end > vas->vm_end || start < vas->vm_start) {
> > -           err = -EINVAL;
> > -           goto err_out;
> > -   }
> > -
> > -   if (!vma_is_anonymous(vas)) {
> > -           err = -EBUSY;
> > -           goto err_out;
> > -   }
> > -
> > -   buf = kvcalloc(npages, 2 * sizeof(*migrate.src) + sizeof(*dma_addr) +
> > -                  sizeof(*pages), GFP_KERNEL);
> > -   if (!buf) {
> > -           err = -ENOMEM;
> > -           goto err_out;
> > -   }
> > -   dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
> > -   pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr)) * npages;
> > -
> > -   zdd = drm_gpusvm_zdd_alloc(gpusvm->device_private_page_owner);
> > -   if (!zdd) {
> > -           err = -ENOMEM;
> > -           goto err_free;
> > -   }
> > -
> > -   migrate.vma = vas;
> > -   migrate.src = buf;
> > -   migrate.dst = migrate.src + npages;
> > -
> > -   err = migrate_vma_setup(&migrate);
> > -   if (err)
> > -           goto err_free;
> > -
> > -   if (!migrate.cpages) {
> > -           err = -EFAULT;
> > -           goto err_free;
> > -   }
> > -
> > -   if (migrate.cpages != npages) {
> > -           err = -EBUSY;
> > -           goto err_finalize;
> > -   }
> > -
> > -   err = ops->populate_devmem_pfn(devmem_allocation, npages, migrate.dst);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -   err = drm_gpusvm_migrate_map_pages(devmem_allocation->dev, dma_addr,
> > -                                      migrate.src, npages, DMA_TO_DEVICE);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -   for (i = 0; i < npages; ++i) {
> > -           struct page *page = pfn_to_page(migrate.dst[i]);
> > -
> > -           pages[i] = page;
> > -           migrate.dst[i] = migrate_pfn(migrate.dst[i]);
> > -           drm_gpusvm_get_devmem_page(page, zdd);
> > -   }
> > -
> > -   err = ops->copy_to_devmem(pages, dma_addr, npages);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -   /* Upon success bind devmem allocation to range and zdd */
> > -   devmem_allocation->timeslice_expiration = get_jiffies_64() +
> > -           msecs_to_jiffies(ctx->timeslice_ms);
> > -   zdd->devmem_allocation = devmem_allocation;     /* Owns ref */
> > -
> > -err_finalize:
> > -   if (err)
> > -           drm_gpusvm_migration_unlock_put_pages(npages, migrate.dst);
> > -   migrate_vma_pages(&migrate);
> > -   migrate_vma_finalize(&migrate);
> > -   drm_gpusvm_migrate_unmap_pages(devmem_allocation->dev, dma_addr, npages,
> > -                                  DMA_TO_DEVICE);
> > -err_free:
> > -   if (zdd)
> > -           drm_gpusvm_zdd_put(zdd);
> > -   kvfree(buf);
> > -err_out:
> > -   return err;
> > -}
> > -EXPORT_SYMBOL_GPL(drm_gpusvm_migrate_to_devmem);
> > -
> > -/**
> > - * drm_gpusvm_migrate_populate_ram_pfn() - Populate RAM PFNs for a VM area
> > - * @vas: Pointer to the VM area structure, can be NULL
> > - * @fault_page: Fault page
> > - * @npages: Number of pages to populate
> > - * @mpages: Number of pages to migrate
> > - * @src_mpfn: Source array of migrate PFNs
> > - * @mpfn: Array of migrate PFNs to populate
> > - * @addr: Start address for PFN allocation
> > - *
> > - * This function populates the RAM migrate page frame numbers (PFNs) for 
> > the
> > - * specified VM area structure. It allocates and locks pages in the VM 
> > area for
> > - * RAM usage. If vas is non-NULL use alloc_page_vma for allocation, if 
> > NULL use
> > - * alloc_page for allocation.
> > - *
> > - * Return: 0 on success, negative error code on failure.
> > - */
> > -static int drm_gpusvm_migrate_populate_ram_pfn(struct vm_area_struct *vas,
> > -                                          struct page *fault_page,
> > -                                          unsigned long npages,
> > -                                          unsigned long *mpages,
> > -                                          unsigned long *src_mpfn,
> > -                                          unsigned long *mpfn,
> > -                                          unsigned long addr)
> > -{
> > -   unsigned long i;
> > -
> > -   for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
> > -           struct page *page, *src_page;
> > -
> > -           if (!(src_mpfn[i] & MIGRATE_PFN_MIGRATE))
> > -                   continue;
> > -
> > -           src_page = migrate_pfn_to_page(src_mpfn[i]);
> > -           if (!src_page)
> > -                   continue;
> > -
> > -           if (fault_page) {
> > -                   if (src_page->zone_device_data !=
> > -                       fault_page->zone_device_data)
> > -                           continue;
> > -           }
> > -
> > -           if (vas)
> > -                   page = alloc_page_vma(GFP_HIGHUSER, vas, addr);
> > -           else
> > -                   page = alloc_page(GFP_HIGHUSER);
> > -
> > -           if (!page)
> > -                   goto free_pages;
> > -
> > -           mpfn[i] = migrate_pfn(page_to_pfn(page));
> > -   }
> > -
> > -   for (i = 0; i < npages; ++i) {
> > -           struct page *page = migrate_pfn_to_page(mpfn[i]);
> > -
> > -           if (!page)
> > -                   continue;
> > -
> > -           WARN_ON_ONCE(!trylock_page(page));
> > -           ++*mpages;
> > -   }
> > -
> > -   return 0;
> > -
> > -free_pages:
> > -   for (i = 0; i < npages; ++i) {
> > -           struct page *page = migrate_pfn_to_page(mpfn[i]);
> > -
> > -           if (!page)
> > -                   continue;
> > -
> > -           put_page(page);
> > -           mpfn[i] = 0;
> > -   }
> > -   return -ENOMEM;
> > -}
> > -
> > -/**
> > - * drm_gpusvm_evict_to_ram() - Evict GPU SVM range to RAM
> > - * @devmem_allocation: Pointer to the device memory allocation
> > - *
> > - * Similar to __drm_gpusvm_migrate_to_ram but does not require mmap lock 
> > and
> > - * migration done via migrate_device_* functions.
> > - *
> > - * Return: 0 on success, negative error code on failure.
> > - */
> > -int drm_gpusvm_evict_to_ram(struct drm_gpusvm_devmem *devmem_allocation)
> > -{
> > -   const struct drm_gpusvm_devmem_ops *ops = devmem_allocation->ops;
> > -   unsigned long npages, mpages = 0;
> > -   struct page **pages;
> > -   unsigned long *src, *dst;
> > -   dma_addr_t *dma_addr;
> > -   void *buf;
> > -   int i, err = 0;
> > -   unsigned int retry_count = 2;
> > -
> > -   npages = devmem_allocation->size >> PAGE_SHIFT;
> > -
> > -retry:
> > -   if (!mmget_not_zero(devmem_allocation->mm))
> > -           return -EFAULT;
> > -
> > -   buf = kvcalloc(npages, 2 * sizeof(*src) + sizeof(*dma_addr) +
> > -                  sizeof(*pages), GFP_KERNEL);
> > -   if (!buf) {
> > -           err = -ENOMEM;
> > -           goto err_out;
> > -   }
> > -   src = buf;
> > -   dst = buf + (sizeof(*src) * npages);
> > -   dma_addr = buf + (2 * sizeof(*src) * npages);
> > -   pages = buf + (2 * sizeof(*src) + sizeof(*dma_addr)) * npages;
> > -
> > -   err = ops->populate_devmem_pfn(devmem_allocation, npages, src);
> > -   if (err)
> > -           goto err_free;
> > -
> > -   err = migrate_device_pfns(src, npages);
> > -   if (err)
> > -           goto err_free;
> > -
> > -   err = drm_gpusvm_migrate_populate_ram_pfn(NULL, NULL, npages, &mpages,
> > -                                             src, dst, 0);
> > -   if (err || !mpages)
> > -           goto err_finalize;
> > -
> > -   err = drm_gpusvm_migrate_map_pages(devmem_allocation->dev, dma_addr,
> > -                                      dst, npages, DMA_FROM_DEVICE);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -   for (i = 0; i < npages; ++i)
> > -           pages[i] = migrate_pfn_to_page(src[i]);
> > -
> > -   err = ops->copy_to_ram(pages, dma_addr, npages);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -err_finalize:
> > -   if (err)
> > -           drm_gpusvm_migration_unlock_put_pages(npages, dst);
> > -   migrate_device_pages(src, dst, npages);
> > -   migrate_device_finalize(src, dst, npages);
> > -   drm_gpusvm_migrate_unmap_pages(devmem_allocation->dev, dma_addr, npages,
> > -                                  DMA_FROM_DEVICE);
> > -err_free:
> > -   kvfree(buf);
> > -err_out:
> > -   mmput_async(devmem_allocation->mm);
> > -
> > -   if (completion_done(&devmem_allocation->detached))
> > -           return 0;
> > -
> > -   if (retry_count--) {
> > -           cond_resched();
> > -           goto retry;
> > -   }
> > -
> > -   return err ?: -EBUSY;
> > -}
> > -EXPORT_SYMBOL_GPL(drm_gpusvm_evict_to_ram);
> > -
> > -/**
> > - * __drm_gpusvm_migrate_to_ram() - Migrate GPU SVM range to RAM (internal)
> > - * @vas: Pointer to the VM area structure
> > - * @device_private_page_owner: Device private pages owner
> > - * @page: Pointer to the page for fault handling (can be NULL)
> > - * @fault_addr: Fault address
> > - * @size: Size of migration
> > - *
> > - * This internal function performs the migration of the specified GPU SVM 
> > range
> > - * to RAM. It sets up the migration, populates + dma maps RAM PFNs, and
> > - * invokes the driver-specific operations for migration to RAM.
> > - *
> > - * Return: 0 on success, negative error code on failure.
> > - */
> > -static int __drm_gpusvm_migrate_to_ram(struct vm_area_struct *vas,
> > -                                  void *device_private_page_owner,
> > -                                  struct page *page,
> > -                                  unsigned long fault_addr,
> > -                                  unsigned long size)
> > -{
> > -   struct migrate_vma migrate = {
> > -           .vma            = vas,
> > -           .pgmap_owner    = device_private_page_owner,
> > -           .flags          = MIGRATE_VMA_SELECT_DEVICE_PRIVATE |
> > -                   MIGRATE_VMA_SELECT_DEVICE_COHERENT,
> > -           .fault_page     = page,
> > -   };
> > -   struct drm_gpusvm_zdd *zdd;
> > -   const struct drm_gpusvm_devmem_ops *ops;
> > -   struct device *dev = NULL;
> > -   unsigned long npages, mpages = 0;
> > -   struct page **pages;
> > -   dma_addr_t *dma_addr;
> > -   unsigned long start, end;
> > -   void *buf;
> > -   int i, err = 0;
> > -
> > -   if (page) {
> > -           zdd = page->zone_device_data;
> > -           if (time_before64(get_jiffies_64(),
> > -                             zdd->devmem_allocation->timeslice_expiration))
> > -                   return 0;
> > -   }
> > -
> > -   start = ALIGN_DOWN(fault_addr, size);
> > -   end = ALIGN(fault_addr + 1, size);
> > -
> > -   /* Corner where VMA area struct has been partially unmapped */
> > -   if (start < vas->vm_start)
> > -           start = vas->vm_start;
> > -   if (end > vas->vm_end)
> > -           end = vas->vm_end;
> > -
> > -   migrate.start = start;
> > -   migrate.end = end;
> > -   npages = npages_in_range(start, end);
> > -
> > -   buf = kvcalloc(npages, 2 * sizeof(*migrate.src) + sizeof(*dma_addr) +
> > -                  sizeof(*pages), GFP_KERNEL);
> > -   if (!buf) {
> > -           err = -ENOMEM;
> > -           goto err_out;
> > -   }
> > -   dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
> > -   pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr)) * npages;
> > -
> > -   migrate.vma = vas;
> > -   migrate.src = buf;
> > -   migrate.dst = migrate.src + npages;
> > -
> > -   err = migrate_vma_setup(&migrate);
> > -   if (err)
> > -           goto err_free;
> > -
> > -   /* Raced with another CPU fault, nothing to do */
> > -   if (!migrate.cpages)
> > -           goto err_free;
> > -
> > -   if (!page) {
> > -           for (i = 0; i < npages; ++i) {
> > -                   if (!(migrate.src[i] & MIGRATE_PFN_MIGRATE))
> > -                           continue;
> > -
> > -                   page = migrate_pfn_to_page(migrate.src[i]);
> > -                   break;
> > -           }
> > -
> > -           if (!page)
> > -                   goto err_finalize;
> > -   }
> > -   zdd = page->zone_device_data;
> > -   ops = zdd->devmem_allocation->ops;
> > -   dev = zdd->devmem_allocation->dev;
> > -
> > -   err = drm_gpusvm_migrate_populate_ram_pfn(vas, page, npages, &mpages,
> > -                                             migrate.src, migrate.dst,
> > -                                             start);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -   err = drm_gpusvm_migrate_map_pages(dev, dma_addr, migrate.dst, npages,
> > -                                      DMA_FROM_DEVICE);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -   for (i = 0; i < npages; ++i)
> > -           pages[i] = migrate_pfn_to_page(migrate.src[i]);
> > -
> > -   err = ops->copy_to_ram(pages, dma_addr, npages);
> > -   if (err)
> > -           goto err_finalize;
> > -
> > -err_finalize:
> > -   if (err)
> > -           drm_gpusvm_migration_unlock_put_pages(npages, migrate.dst);
> > -   migrate_vma_pages(&migrate);
> > -   migrate_vma_finalize(&migrate);
> > -   if (dev)
> > -           drm_gpusvm_migrate_unmap_pages(dev, dma_addr, npages,
> > -                                          DMA_FROM_DEVICE);
> > -err_free:
> > -   kvfree(buf);
> > -err_out:
> > -
> > -   return err;
> > -}
> > -
> > -/**
> > - * drm_gpusvm_range_evict - Evict GPU SVM range
> >    * @range: Pointer to the GPU SVM range to be removed
> >    *
> > - * This function evicts the specified GPU SVM range. This function will not
> > - * evict coherent pages.
> > + * This function evicts the specified GPU SVM range.
> >    *
> >    * Return: 0 on success, a negative error code on failure.
> >    */
> > @@ -2182,60 +1525,6 @@ int drm_gpusvm_range_evict(struct drm_gpusvm *gpusvm,
> >   }
> >   EXPORT_SYMBOL_GPL(drm_gpusvm_range_evict);
> > -/**
> > - * drm_gpusvm_page_free() - Put GPU SVM zone device data associated with a 
> > page
> > - * @page: Pointer to the page
> > - *
> > - * This function is a callback used to put the GPU SVM zone device data
> > - * associated with a page when it is being released.
> > - */
> > -static void drm_gpusvm_page_free(struct page *page)
> > -{
> > -   drm_gpusvm_zdd_put(page->zone_device_data);
> > -}
> > -
> > -/**
> > - * drm_gpusvm_migrate_to_ram() - Migrate GPU SVM range to RAM (page fault 
> > handler)
> > - * @vmf: Pointer to the fault information structure
> > - *
> > - * This function is a page fault handler used to migrate a GPU SVM range 
> > to RAM.
> > - * It retrieves the GPU SVM range information from the faulting page and 
> > invokes
> > - * the internal migration function to migrate the range back to RAM.
> > - *
> > - * Return: VM_FAULT_SIGBUS on failure, 0 on success.
> > - */
> > -static vm_fault_t drm_gpusvm_migrate_to_ram(struct vm_fault *vmf)
> > -{
> > -   struct drm_gpusvm_zdd *zdd = vmf->page->zone_device_data;
> > -   int err;
> > -
> > -   err = __drm_gpusvm_migrate_to_ram(vmf->vma,
> > -                                     zdd->device_private_page_owner,
> > -                                     vmf->page, vmf->address,
> > -                                     zdd->devmem_allocation->size);
> > -
> > -   return err ? VM_FAULT_SIGBUS : 0;
> > -}
> > -
> > -/*
> > - * drm_gpusvm_pagemap_ops - Device page map operations for GPU SVM
> > - */
> > -static const struct dev_pagemap_ops drm_gpusvm_pagemap_ops = {
> > -   .page_free = drm_gpusvm_page_free,
> > -   .migrate_to_ram = drm_gpusvm_migrate_to_ram,
> > -};
> > -
> > -/**
> > - * drm_gpusvm_pagemap_ops_get() - Retrieve GPU SVM device page map 
> > operations
> > - *
> > - * Return: Pointer to the GPU SVM device page map operations structure.
> > - */
> > -const struct dev_pagemap_ops *drm_gpusvm_pagemap_ops_get(void)
> > -{
> > -   return &drm_gpusvm_pagemap_ops;
> > -}
> > -EXPORT_SYMBOL_GPL(drm_gpusvm_pagemap_ops_get);
> > -
> >   /**
> >    * drm_gpusvm_has_mapping() - Check if GPU SVM has mapping for the given 
> > address range
> >    * @gpusvm: Pointer to the GPU SVM structure.
> > @@ -2280,28 +1569,5 @@ void drm_gpusvm_range_set_unmapped(struct 
> > drm_gpusvm_range *range,
> >   }
> >   EXPORT_SYMBOL_GPL(drm_gpusvm_range_set_unmapped);
> > -/**
> > - * drm_gpusvm_devmem_init() - Initialize a GPU SVM device memory allocation
> > - *
> > - * @dev: Pointer to the device structure which device memory allocation 
> > belongs to
> > - * @mm: Pointer to the mm_struct for the address space
> > - * @ops: Pointer to the operations structure for GPU SVM device memory
> > - * @dpagemap: The struct drm_pagemap we're allocating from.
> > - * @size: Size of device memory allocation
> > - */
> > -void drm_gpusvm_devmem_init(struct drm_gpusvm_devmem *devmem_allocation,
> > -                       struct device *dev, struct mm_struct *mm,
> > -                       const struct drm_gpusvm_devmem_ops *ops,
> > -                       struct drm_pagemap *dpagemap, size_t size)
> > -{
> > -   init_completion(&devmem_allocation->detached);
> > -   devmem_allocation->dev = dev;
> > -   devmem_allocation->mm = mm;
> > -   devmem_allocation->ops = ops;
> > -   devmem_allocation->dpagemap = dpagemap;
> > -   devmem_allocation->size = size;
> > -}
> > -EXPORT_SYMBOL_GPL(drm_gpusvm_devmem_init);
> > -
> >   MODULE_DESCRIPTION("DRM GPUSVM");
> >   MODULE_LICENSE("GPL");
> > diff --git a/drivers/gpu/drm/drm_pagemap.c b/drivers/gpu/drm/drm_pagemap.c
> > new file mode 100644
> > index 000000000000..cef4657b6e8a
> > --- /dev/null
> > +++ b/drivers/gpu/drm/drm_pagemap.c
> > @@ -0,0 +1,794 @@
> > +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> > +/*
> > + * Copyright © 2024-2025 Intel Corporation
> > + */
> > +
> > +#include <linux/dma-mapping.h>
> > +#include <linux/migrate.h>
> > +#include <linux/pagemap.h>
> > +#include <drm/drm_pagemap.h>
> > +
> > +/**
> > + * DOC: Overview
> > + *
> > + * The DRM pagemap layer is intended to augment the dev_pagemap 
> > functionality by
> > + * providing a way to populate a struct mm_struct virtual range with device
> > + * private pages and to provide helpers to abstract device memory 
> > allocations,
> > + * to migrate memory back and forth between device memory and system RAM 
> > and
> > + * to handle access (and in the future migration) between devices 
> > implementing
> > + * a fast interconnect that is not necessarily visible to the rest of the
> > + * system.
> > + *
> > + * Typically the DRM pagemap receives requests from one or more DRM GPU SVM
> > + * instances to populate struct mm_struct virtual ranges with memory.
> > + */
> > +
> > +/**
> > + * DOC: Migration
> > + *
> > + * The migration support is quite simple, allowing migration between RAM 
> > and
> > + * device memory at the range granularity. For example, GPU SVM currently 
> > does
> > + * not support mixing RAM and device memory pages within a range. This 
> > means
> > + * that upon GPU fault, the entire range can be migrated to device memory, 
> > and
> > + * upon CPU fault, the entire range is migrated to RAM. Mixed RAM and 
> > device
> > + * memory storage within a range could be added in the future if required.
> > + *
> > + * The reasoning for only supporting range granularity is as follows: it
> > + * simplifies the implementation, and range sizes are driver-defined and 
> > should
> > + * be relatively small.
> > + *
> > + *
> > + * Key DRM pagemap components:
> > + *
> > + * - Device Memory Allocations:
> > + *      Embedded structure containing enough information for the 
> > drm_pagemap to
> > + *      migrate to / from device memory.
> > + *
> > + * - Device Memory Operations:
> > + *      Define the interface for driver-specific device memory operations
> > + *      release memory, populate pfns, and copy to / from device memory.
> > + */
> > +
> > +/**
> > + * struct drm_pagemap_zdd - GPU SVM zone device data
> > + *
> > + * @refcount: Reference count for the zdd
> > + * @devmem_allocation: device memory allocation
> > + * @device_private_page_owner: Device private pages owner
> > + *
> > + * This structure serves as a generic wrapper installed in
> > + * page->zone_device_data. It provides infrastructure for looking up a 
> > device
> > + * memory allocation upon CPU page fault and asynchronously releasing 
> > device
> > + * memory once the CPU has no page references. Asynchronous release is 
> > useful
> > + * because CPU page references can be dropped in IRQ contexts, while 
> > releasing
> > + * device memory likely requires sleeping locks.
> > + */
> > +struct drm_pagemap_zdd {
> > +   struct kref refcount;
> > +   struct drm_pagemap_devmem *devmem_allocation;
> > +   void *device_private_page_owner;
> > +};
> > +
> > +/**
> > + * drm_pagemap_zdd_alloc() - Allocate a zdd structure.
> > + * @device_private_page_owner: Device private pages owner
> > + *
> > + * This function allocates and initializes a new zdd structure. It sets up 
> > the
> > + * reference count and initializes the destroy work.
> > + *
> > + * Return: Pointer to the allocated zdd on success, ERR_PTR() on failure.
> > + */
> > +static struct drm_pagemap_zdd *
> > +drm_pagemap_zdd_alloc(void *device_private_page_owner)
> > +{
> > +   struct drm_pagemap_zdd *zdd;
> > +
> > +   zdd = kmalloc(sizeof(*zdd), GFP_KERNEL);
> > +   if (!zdd)
> > +           return NULL;
> > +
> > +   kref_init(&zdd->refcount);
> > +   zdd->devmem_allocation = NULL;
> > +   zdd->device_private_page_owner = device_private_page_owner;
> > +
> > +   return zdd;
> > +}
> > +
> > +/**
> > + * drm_pagemap_zdd_get() - Get a reference to a zdd structure.
> > + * @zdd: Pointer to the zdd structure.
> > + *
> > + * This function increments the reference count of the provided zdd 
> > structure.
> > + *
> > + * Return: Pointer to the zdd structure.
> > + */
> > +static struct drm_pagemap_zdd *drm_pagemap_zdd_get(struct drm_pagemap_zdd 
> > *zdd)
> > +{
> > +   kref_get(&zdd->refcount);
> > +   return zdd;
> > +}
> > +
> > +/**
> > + * drm_pagemap_zdd_destroy() - Destroy a zdd structure.
> > + * @ref: Pointer to the reference count structure.
> > + *
> > + * This function queues the destroy_work of the zdd for asynchronous 
> > destruction.
> > + */
> > +static void drm_pagemap_zdd_destroy(struct kref *ref)
> > +{
> > +   struct drm_pagemap_zdd *zdd =
> > +           container_of(ref, struct drm_pagemap_zdd, refcount);
> > +   struct drm_pagemap_devmem *devmem = zdd->devmem_allocation;
> > +
> > +   if (devmem) {
> > +           complete_all(&devmem->detached);
> > +           if (devmem->ops->devmem_release)
> > +                   devmem->ops->devmem_release(devmem);
> > +   }
> > +   kfree(zdd);
> > +}
> > +
> > +/**
> > + * drm_pagemap_zdd_put() - Put a zdd reference.
> > + * @zdd: Pointer to the zdd structure.
> > + *
> > + * This function decrements the reference count of the provided zdd 
> > structure
> > + * and schedules its destruction if the count drops to zero.
> > + */
> > +static void drm_pagemap_zdd_put(struct drm_pagemap_zdd *zdd)
> > +{
> > +   kref_put(&zdd->refcount, drm_pagemap_zdd_destroy);
> > +}
> > +
> > +/**
> > + * drm_pagemap_migration_unlock_put_page() - Put a migration page
> > + * @page: Pointer to the page to put
> > + *
> > + * This function unlocks and puts a page.
> > + */
> > +static void drm_pagemap_migration_unlock_put_page(struct page *page)
> > +{
> > +   unlock_page(page);
> > +   put_page(page);
> > +}
> > +
> > +/**
> > + * drm_pagemap_migration_unlock_put_pages() - Put migration pages
> > + * @npages: Number of pages
> > + * @migrate_pfn: Array of migrate page frame numbers
> > + *
> > + * This function unlocks and puts an array of pages.
> > + */
> > +static void drm_pagemap_migration_unlock_put_pages(unsigned long npages,
> > +                                              unsigned long *migrate_pfn)
> > +{
> > +   unsigned long i;
> > +
> > +   for (i = 0; i < npages; ++i) {
> > +           struct page *page;
> > +
> > +           if (!migrate_pfn[i])
> > +                   continue;
> > +
> > +           page = migrate_pfn_to_page(migrate_pfn[i]);
> > +           drm_pagemap_migration_unlock_put_page(page);
> > +           migrate_pfn[i] = 0;
> > +   }
> > +}
> > +
> > +/**
> > + * drm_pagemap_get_devmem_page() - Get a reference to a device memory page
> > + * @page: Pointer to the page
> > + * @zdd: Pointer to the GPU SVM zone device data
> > + *
> > + * This function associates the given page with the specified GPU SVM zone
> > + * device data and initializes it for zone device usage.
> > + */
> > +static void drm_pagemap_get_devmem_page(struct page *page,
> > +                                   struct drm_pagemap_zdd *zdd)
> > +{
> > +   page->zone_device_data = drm_pagemap_zdd_get(zdd);
> > +   zone_device_page_init(page);
> > +}
> > +
> > +/**
> > + * drm_pagemap_migrate_map_pages() - Map migration pages for GPU SVM 
> > migration
> > + * @dev: The device for which the pages are being mapped
> > + * @dma_addr: Array to store DMA addresses corresponding to mapped pages
> > + * @migrate_pfn: Array of migrate page frame numbers to map
> > + * @npages: Number of pages to map
> > + * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
> > + *
> > + * This function maps pages of memory for migration usage in GPU SVM. It
> > + * iterates over each page frame number provided in @migrate_pfn, maps the
> > + * corresponding page, and stores the DMA address in the provided @dma_addr
> > + * array.
> > + *
> > + * Returns: 0 on success, -EFAULT if an error occurs during mapping.
> > + */
> > +static int drm_pagemap_migrate_map_pages(struct device *dev,
> > +                                    dma_addr_t *dma_addr,
> > +                                    unsigned long *migrate_pfn,
> > +                                    unsigned long npages,
> > +                                    enum dma_data_direction dir)
> > +{
> > +   unsigned long i;
> > +
> > +   for (i = 0; i < npages; ++i) {
> > +           struct page *page = migrate_pfn_to_page(migrate_pfn[i]);
> > +
> > +           if (!page)
> > +                   continue;
> > +
> > +           if (WARN_ON_ONCE(is_zone_device_page(page)))
> > +                   return -EFAULT;
> > +
> > +           dma_addr[i] = dma_map_page(dev, page, 0, PAGE_SIZE, dir);
> > +           if (dma_mapping_error(dev, dma_addr[i]))
> > +                   return -EFAULT;
> > +   }
> > +
> > +   return 0;
> > +}
> > +
> > +/**
> > + * drm_pagemap_migrate_unmap_pages() - Unmap pages previously mapped for 
> > GPU SVM migration
> > + * @dev: The device for which the pages were mapped
> > + * @dma_addr: Array of DMA addresses corresponding to mapped pages
> > + * @npages: Number of pages to unmap
> > + * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
> > + *
> > + * This function unmaps previously mapped pages of memory for GPU Shared 
> > Virtual
> > + * Memory (SVM). It iterates over each DMA address provided in @dma_addr, 
> > checks
> > + * if it's valid and not already unmapped, and unmaps the corresponding 
> > page.
> > + */
> > +static void drm_pagemap_migrate_unmap_pages(struct device *dev,
> > +                                       dma_addr_t *dma_addr,
> > +                                       unsigned long npages,
> > +                                       enum dma_data_direction dir)
> > +{
> > +   unsigned long i;
> > +
> > +   for (i = 0; i < npages; ++i) {
> > +           if (!dma_addr[i] || dma_mapping_error(dev, dma_addr[i]))
> > +                   continue;
> > +
> > +           dma_unmap_page(dev, dma_addr[i], PAGE_SIZE, dir);
> > +   }
> > +}
> > +
> > +static unsigned long
> > +npages_in_range(unsigned long start, unsigned long end)
> > +{
> > +   return (end - start) >> PAGE_SHIFT;
> > +}
> > +
> > +/**
> > + * drm_pagemap_migrate_to_devmem() - Migrate a struct mm_struct range to 
> > device memory
> > + * @devmem_allocation: The device memory allocation to migrate to.
> > + * The caller should hold a reference to the device memory allocation,
> > + * and the reference is consumed by this function unless it returns with
> > + * an error.
> > + * @mm: Pointer to the struct mm_struct.
> > + * @start: Start of the virtual address range to migrate.
> > + * @end: End of the virtual address range to migrate.
> > + * @timeslice_ms: The time requested for the migrated pagemap pages to
> > + * be present in @mm before being allowed to be migrated back.
> > + * @pgmap_owner: Not used currently, since only system memory is 
> > considered.
> > + *
> > + * This function migrates the specified virtual address range to device 
> > memory.
> > + * It performs the necessary setup and invokes the driver-specific 
> > operations for
> > + * migration to device memory. Expected to be called while holding the 
> > mmap lock in
> > + * at least read mode.
> > + *
> > + * Note: The @timeslice_ms parameter can typically be used to force data to
> > + * remain in pagemap pages long enough for a GPU to perform a task and to 
> > prevent
> > + * a migration livelock. One alternative would be for the GPU driver to 
> > block
> > + * in a mmu_notifier for the specified amount of time, but adding the
> > + * functionality to the pagemap is likely nicer to the system as a whole.
> > + *
> > + * Return: %0 on success, negative error code on failure.
> > + */
> > +int drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem 
> > *devmem_allocation,
> > +                             struct mm_struct *mm,
> > +                             unsigned long start, unsigned long end,
> > +                             unsigned long timeslice_ms,
> > +                             void *pgmap_owner)
> > +{
> > +   const struct drm_pagemap_devmem_ops *ops = devmem_allocation->ops;
> > +   struct migrate_vma migrate = {
> > +           .start          = start,
> > +           .end            = end,
> > +           .pgmap_owner    = pgmap_owner,
> > +           .flags          = MIGRATE_VMA_SELECT_SYSTEM,
> > +   };
> > +   unsigned long i, npages = npages_in_range(start, end);
> > +   struct vm_area_struct *vas;
> > +   struct drm_pagemap_zdd *zdd = NULL;
> > +   struct page **pages;
> > +   dma_addr_t *dma_addr;
> > +   void *buf;
> > +   int err;
> > +
> > +   mmap_assert_locked(mm);
> > +
> > +   if (!ops->populate_devmem_pfn || !ops->copy_to_devmem ||
> > +       !ops->copy_to_ram)
> > +           return -EOPNOTSUPP;
> > +
> > +   vas = vma_lookup(mm, start);
> > +   if (!vas) {
> > +           err = -ENOENT;
> > +           goto err_out;
> > +   }
> > +
> > +   if (end > vas->vm_end || start < vas->vm_start) {
> > +           err = -EINVAL;
> > +           goto err_out;
> > +   }
> > +
> > +   if (!vma_is_anonymous(vas)) {
> > +           err = -EBUSY;
> > +           goto err_out;
> > +   }
> > +
> > +   buf = kvcalloc(npages, 2 * sizeof(*migrate.src) + sizeof(*dma_addr) +
> > +                  sizeof(*pages), GFP_KERNEL);
> > +   if (!buf) {
> > +           err = -ENOMEM;
> > +           goto err_out;
> > +   }
> > +   dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
> > +   pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr)) * npages;
> > +
> > +   zdd = drm_pagemap_zdd_alloc(pgmap_owner);
> > +   if (!zdd) {
> > +           err = -ENOMEM;
> > +           goto err_free;
> > +   }
> > +
> > +   migrate.vma = vas;
> > +   migrate.src = buf;
> > +   migrate.dst = migrate.src + npages;
> > +
> > +   err = migrate_vma_setup(&migrate);
> > +   if (err)
> > +           goto err_free;
> > +
> > +   if (!migrate.cpages) {
> > +           err = -EFAULT;
> > +           goto err_free;
> > +   }
> > +
> > +   if (migrate.cpages != npages) {
> > +           err = -EBUSY;
> > +           goto err_finalize;
> > +   }
> > +
> > +   err = ops->populate_devmem_pfn(devmem_allocation, npages, migrate.dst);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +   err = drm_pagemap_migrate_map_pages(devmem_allocation->dev, dma_addr,
> > +                                       migrate.src, npages, DMA_TO_DEVICE);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +   for (i = 0; i < npages; ++i) {
> > +           struct page *page = pfn_to_page(migrate.dst[i]);
> > +
> > +           pages[i] = page;
> > +           migrate.dst[i] = migrate_pfn(migrate.dst[i]);
> > +           drm_pagemap_get_devmem_page(page, zdd);
> > +   }
> > +
> > +   err = ops->copy_to_devmem(pages, dma_addr, npages);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +   /* Upon success bind devmem allocation to range and zdd */
> > +   devmem_allocation->timeslice_expiration = get_jiffies_64() +
> > +           msecs_to_jiffies(timeslice_ms);
> > +   zdd->devmem_allocation = devmem_allocation;     /* Owns ref */
> > +
> > +err_finalize:
> > +   if (err)
> > +           drm_pagemap_migration_unlock_put_pages(npages, migrate.dst);
> > +   migrate_vma_pages(&migrate);
> > +   migrate_vma_finalize(&migrate);
> > +   drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, dma_addr, 
> > npages,
> > +                                   DMA_TO_DEVICE);
> > +err_free:
> > +   if (zdd)
> > +           drm_pagemap_zdd_put(zdd);
> > +   kvfree(buf);
> > +err_out:
> > +   return err;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_pagemap_migrate_to_devmem);
> > +
> > +/**
> > + * drm_pagemap_migrate_populate_ram_pfn() - Populate RAM PFNs for a VM area
> > + * @vas: Pointer to the VM area structure, can be NULL
> > + * @fault_page: Fault page
> > + * @npages: Number of pages to populate
> > + * @mpages: Number of pages to migrate
> > + * @src_mpfn: Source array of migrate PFNs
> > + * @mpfn: Array of migrate PFNs to populate
> > + * @addr: Start address for PFN allocation
> > + *
> > + * This function populates the RAM migrate page frame numbers (PFNs) for 
> > the
> > + * specified VM area structure. It allocates and locks pages in the VM 
> > area for
> > + * RAM usage. If vas is non-NULL use alloc_page_vma for allocation, if 
> > NULL use
> > + * alloc_page for allocation.
> > + *
> > + * Return: 0 on success, negative error code on failure.
> > + */
> > +static int drm_pagemap_migrate_populate_ram_pfn(struct vm_area_struct *vas,
> > +                                           struct page *fault_page,
> > +                                           unsigned long npages,
> > +                                           unsigned long *mpages,
> > +                                           unsigned long *src_mpfn,
> > +                                           unsigned long *mpfn,
> > +                                           unsigned long addr)
> > +{
> > +   unsigned long i;
> > +
> > +   for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
> > +           struct page *page, *src_page;
> > +
> > +           if (!(src_mpfn[i] & MIGRATE_PFN_MIGRATE))
> > +                   continue;
> > +
> > +           src_page = migrate_pfn_to_page(src_mpfn[i]);
> > +           if (!src_page)
> > +                   continue;
> > +
> > +           if (fault_page) {
> > +                   if (src_page->zone_device_data !=
> > +                       fault_page->zone_device_data)
> > +                           continue;
> > +           }
> > +
> > +           if (vas)
> > +                   page = alloc_page_vma(GFP_HIGHUSER, vas, addr);
> > +           else
> > +                   page = alloc_page(GFP_HIGHUSER);
> > +
> > +           if (!page)
> > +                   goto free_pages;
> > +
> > +           mpfn[i] = migrate_pfn(page_to_pfn(page));
> > +   }
> > +
> > +   for (i = 0; i < npages; ++i) {
> > +           struct page *page = migrate_pfn_to_page(mpfn[i]);
> > +
> > +           if (!page)
> > +                   continue;
> > +
> > +           WARN_ON_ONCE(!trylock_page(page));
> > +           ++*mpages;
> > +   }
> > +
> > +   return 0;
> > +
> > +free_pages:
> > +   for (i = 0; i < npages; ++i) {
> > +           struct page *page = migrate_pfn_to_page(mpfn[i]);
> > +
> > +           if (!page)
> > +                   continue;
> > +
> > +           put_page(page);
> > +           mpfn[i] = 0;
> > +   }
> > +   return -ENOMEM;
> > +}
> > +
> > +/**
> > + * drm_pagemap_evict_to_ram() - Evict GPU SVM range to RAM
> > + * @devmem_allocation: Pointer to the device memory allocation
> > + *
> > + * Similar to __drm_pagemap_migrate_to_ram but does not require mmap lock 
> > and
> > + * migration done via migrate_device_* functions.
> > + *
> > + * Return: 0 on success, negative error code on failure.
> > + */
> > +int drm_pagemap_evict_to_ram(struct drm_pagemap_devmem *devmem_allocation)
> > +{
> > +   const struct drm_pagemap_devmem_ops *ops = devmem_allocation->ops;
> > +   unsigned long npages, mpages = 0;
> > +   struct page **pages;
> > +   unsigned long *src, *dst;
> > +   dma_addr_t *dma_addr;
> > +   void *buf;
> > +   int i, err = 0;
> > +   unsigned int retry_count = 2;
> > +
> > +   npages = devmem_allocation->size >> PAGE_SHIFT;
> > +
> > +retry:
> > +   if (!mmget_not_zero(devmem_allocation->mm))
> > +           return -EFAULT;
> > +
> > +   buf = kvcalloc(npages, 2 * sizeof(*src) + sizeof(*dma_addr) +
> > +                  sizeof(*pages), GFP_KERNEL);
> > +   if (!buf) {
> > +           err = -ENOMEM;
> > +           goto err_out;
> > +   }
> > +   src = buf;
> > +   dst = buf + (sizeof(*src) * npages);
> > +   dma_addr = buf + (2 * sizeof(*src) * npages);
> > +   pages = buf + (2 * sizeof(*src) + sizeof(*dma_addr)) * npages;
> > +
> > +   err = ops->populate_devmem_pfn(devmem_allocation, npages, src);
> > +   if (err)
> > +           goto err_free;
> > +
> > +   err = migrate_device_pfns(src, npages);
> > +   if (err)
> > +           goto err_free;
> > +
> > +   err = drm_pagemap_migrate_populate_ram_pfn(NULL, NULL, npages, &mpages,
> > +                                              src, dst, 0);
> > +   if (err || !mpages)
> > +           goto err_finalize;
> > +
> > +   err = drm_pagemap_migrate_map_pages(devmem_allocation->dev, dma_addr,
> > +                                       dst, npages, DMA_FROM_DEVICE);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +   for (i = 0; i < npages; ++i)
> > +           pages[i] = migrate_pfn_to_page(src[i]);
> > +
> > +   err = ops->copy_to_ram(pages, dma_addr, npages);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +err_finalize:
> > +   if (err)
> > +           drm_pagemap_migration_unlock_put_pages(npages, dst);
> > +   migrate_device_pages(src, dst, npages);
> > +   migrate_device_finalize(src, dst, npages);
> > +   drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, dma_addr, 
> > npages,
> > +                                   DMA_FROM_DEVICE);
> > +err_free:
> > +   kvfree(buf);
> > +err_out:
> > +   mmput_async(devmem_allocation->mm);
> > +
> > +   if (completion_done(&devmem_allocation->detached))
> > +           return 0;
> > +
> > +   if (retry_count--) {
> > +           cond_resched();
> > +           goto retry;
> > +   }
> > +
> > +   return err ?: -EBUSY;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_pagemap_evict_to_ram);
> > +
> > +/**
> > + * __drm_pagemap_migrate_to_ram() - Migrate GPU SVM range to RAM (internal)
> > + * @vas: Pointer to the VM area structure
> > + * @device_private_page_owner: Device private pages owner
> > + * @page: Pointer to the page for fault handling (can be NULL)
> > + * @fault_addr: Fault address
> > + * @size: Size of migration
> > + *
> > + * This internal function performs the migration of the specified GPU SVM 
> > range
> > + * to RAM. It sets up the migration, populates + dma maps RAM PFNs, and
> > + * invokes the driver-specific operations for migration to RAM.
> > + *
> > + * Return: 0 on success, negative error code on failure.
> > + */
> > +static int __drm_pagemap_migrate_to_ram(struct vm_area_struct *vas,
> > +                                   void *device_private_page_owner,
> > +                                   struct page *page,
> > +                                   unsigned long fault_addr,
> > +                                   unsigned long size)
> > +{
> > +   struct migrate_vma migrate = {
> > +           .vma            = vas,
> > +           .pgmap_owner    = device_private_page_owner,
> > +           .flags          = MIGRATE_VMA_SELECT_DEVICE_PRIVATE |
> > +           MIGRATE_VMA_SELECT_DEVICE_COHERENT,
> > +           .fault_page     = page,
> > +   };
> > +   struct drm_pagemap_zdd *zdd;
> > +   const struct drm_pagemap_devmem_ops *ops;
> > +   struct device *dev = NULL;
> > +   unsigned long npages, mpages = 0;
> > +   struct page **pages;
> > +   dma_addr_t *dma_addr;
> > +   unsigned long start, end;
> > +   void *buf;
> > +   int i, err = 0;
> > +
> > +   if (page) {
> > +           zdd = page->zone_device_data;
> > +           if (time_before64(get_jiffies_64(),
> > +                             zdd->devmem_allocation->timeslice_expiration))
> > +                   return 0;
> > +   }
> > +
> > +   start = ALIGN_DOWN(fault_addr, size);
> > +   end = ALIGN(fault_addr + 1, size);
> > +
> > +   /* Corner where VMA area struct has been partially unmapped */
> > +   if (start < vas->vm_start)
> > +           start = vas->vm_start;
> > +   if (end > vas->vm_end)
> > +           end = vas->vm_end;
> > +
> > +   migrate.start = start;
> > +   migrate.end = end;
> > +   npages = npages_in_range(start, end);
> > +
> > +   buf = kvcalloc(npages, 2 * sizeof(*migrate.src) + sizeof(*dma_addr) +
> > +                  sizeof(*pages), GFP_KERNEL);
> > +   if (!buf) {
> > +           err = -ENOMEM;
> > +           goto err_out;
> > +   }
> > +   dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
> > +   pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr)) * npages;
> > +
> > +   migrate.vma = vas;
> > +   migrate.src = buf;
> > +   migrate.dst = migrate.src + npages;
> > +
> > +   err = migrate_vma_setup(&migrate);
> > +   if (err)
> > +           goto err_free;
> > +
> > +   /* Raced with another CPU fault, nothing to do */
> > +   if (!migrate.cpages)
> > +           goto err_free;
> > +
> > +   if (!page) {
> > +           for (i = 0; i < npages; ++i) {
> > +                   if (!(migrate.src[i] & MIGRATE_PFN_MIGRATE))
> > +                           continue;
> > +
> > +                   page = migrate_pfn_to_page(migrate.src[i]);
> > +                   break;
> > +           }
> > +
> > +           if (!page)
> > +                   goto err_finalize;
> > +   }
> > +   zdd = page->zone_device_data;
> > +   ops = zdd->devmem_allocation->ops;
> > +   dev = zdd->devmem_allocation->dev;
> > +
> > +   err = drm_pagemap_migrate_populate_ram_pfn(vas, page, npages, &mpages,
> > +                                              migrate.src, migrate.dst,
> > +                                              start);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +   err = drm_pagemap_migrate_map_pages(dev, dma_addr, migrate.dst, npages,
> > +                                       DMA_FROM_DEVICE);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +   for (i = 0; i < npages; ++i)
> > +           pages[i] = migrate_pfn_to_page(migrate.src[i]);
> > +
> > +   err = ops->copy_to_ram(pages, dma_addr, npages);
> > +   if (err)
> > +           goto err_finalize;
> > +
> > +err_finalize:
> > +   if (err)
> > +           drm_pagemap_migration_unlock_put_pages(npages, migrate.dst);
> > +   migrate_vma_pages(&migrate);
> > +   migrate_vma_finalize(&migrate);
> > +   if (dev)
> > +           drm_pagemap_migrate_unmap_pages(dev, dma_addr, npages,
> > +                                           DMA_FROM_DEVICE);
> > +err_free:
> > +   kvfree(buf);
> > +err_out:
> > +
> > +   return err;
> > +}
> > +
> > +/**
> > + * drm_pagemap_page_free() - Put GPU SVM zone device data associated with 
> > a page
> > + * @page: Pointer to the page
> > + *
> > + * This function is a callback used to put the GPU SVM zone device data
> > + * associated with a page when it is being released.
> > + */
> > +static void drm_pagemap_page_free(struct page *page)
> > +{
> > +   drm_pagemap_zdd_put(page->zone_device_data);
> > +}
> > +
> > +/**
> > + * drm_pagemap_migrate_to_ram() - Migrate a virtual range to RAM (page 
> > fault handler)
> > + * @vmf: Pointer to the fault information structure
> > + *
> > + * This function is a page fault handler used to migrate a virtual range
> > + * to ram. The device memory allocation in which the device page is found 
> > is
> > + * migrated in its entirety.
> > + *
> > + * Returns:
> > + * VM_FAULT_SIGBUS on failure, 0 on success.
> > + */
> > +static vm_fault_t drm_pagemap_migrate_to_ram(struct vm_fault *vmf)
> > +{
> > +   struct drm_pagemap_zdd *zdd = vmf->page->zone_device_data;
> > +   int err;
> > +
> > +   err = __drm_pagemap_migrate_to_ram(vmf->vma,
> > +                                      zdd->device_private_page_owner,
> > +                                      vmf->page, vmf->address,
> > +                                      zdd->devmem_allocation->size);
> > +
> > +   return err ? VM_FAULT_SIGBUS : 0;
> > +}
> > +
> > +static const struct dev_pagemap_ops drm_pagemap_pagemap_ops = {
> > +   .page_free = drm_pagemap_page_free,
> > +   .migrate_to_ram = drm_pagemap_migrate_to_ram,
> > +};
> > +
> > +/**
> > + * drm_pagemap_pagemap_ops_get() - Retrieve GPU SVM device page map 
> > operations
> > + *
> > + * Returns:
> > + * Pointer to the GPU SVM device page map operations structure.
> > + */
> > +const struct dev_pagemap_ops *drm_pagemap_pagemap_ops_get(void)
> > +{
> > +   return &drm_pagemap_pagemap_ops;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_pagemap_pagemap_ops_get);
> > +
> > +/**
> > + * drm_pagemap_devmem_init() - Initialize a drm_pagemap device memory 
> > allocation
> > + *
> > + * @devmem_allocation: The struct drm_pagemap_devmem to initialize.
> > + * @dev: Pointer to the device structure which device memory allocation 
> > belongs to
> > + * @mm: Pointer to the mm_struct for the address space
> > + * @ops: Pointer to the operations structure for GPU SVM device memory
> > + * @dpagemap: The struct drm_pagemap we're allocating from.
> > + * @size: Size of device memory allocation
> > + */
> > +void drm_pagemap_devmem_init(struct drm_pagemap_devmem *devmem_allocation,
> > +                        struct device *dev, struct mm_struct *mm,
> > +                        const struct drm_pagemap_devmem_ops *ops,
> > +                        struct drm_pagemap *dpagemap, size_t size)
> > +{
> > +   init_completion(&devmem_allocation->detached);
> > +   devmem_allocation->dev = dev;
> > +   devmem_allocation->mm = mm;
> > +   devmem_allocation->ops = ops;
> > +   devmem_allocation->dpagemap = dpagemap;
> > +   devmem_allocation->size = size;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_pagemap_devmem_init);
> > +
> > +/**
> > + * drm_pagemap_page_to_dpagemap() - Return a pointer the drm_pagemap of a 
> > page
> > + * @page: The struct page.
> > + *
> > + * Return: A pointer to the struct drm_pagemap of a device private page 
> > that
> > + * was populated from the struct drm_pagemap. If the page was *not* 
> > populated
> > + * from a struct drm_pagemap, the result is undefined and the function call
> > + * may result in dereferencing and invalid address.
> > + */
> > +struct drm_pagemap *drm_pagemap_page_to_dpagemap(struct page *page)
> > +{
> > +   struct drm_pagemap_zdd *zdd = page->zone_device_data;
> > +
> > +   return zdd->devmem_allocation->dpagemap;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_pagemap_page_to_dpagemap);
> > diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
> > index c57f1da0791d..b5eab4d29211 100644
> > --- a/drivers/gpu/drm/xe/Kconfig
> > +++ b/drivers/gpu/drm/xe/Kconfig
> > @@ -86,14 +86,16 @@ config DRM_XE_GPUSVM
> >       If in doubut say "Y".
> > -config DRM_XE_DEVMEM_MIRROR
> > -   bool "Enable device memory mirror"
> > +config DRM_XE_PAGEMAP
> > +   bool "Enable device memory pool for SVM"
> >     depends on DRM_XE_GPUSVM
> >     select GET_FREE_REGION
> >     default y
> >     help
> > -     Disable this option only if you want to compile out without device
> > -     memory mirror. Will reduce KMD memory footprint when disabled.
> > +     Disable this option only if you don't want to expose local device
> > +     memory for SVM. Will reduce KMD memory footprint when disabled.
> > +
> > +     If in doubut say "Y".
> >   config DRM_XE_FORCE_PROBE
> >     string "Force probe xe for selected Intel hardware IDs"
> > diff --git a/drivers/gpu/drm/xe/xe_bo_types.h 
> > b/drivers/gpu/drm/xe/xe_bo_types.h
> > index eb5e83c5f233..e0efaf23d051 100644
> > --- a/drivers/gpu/drm/xe/xe_bo_types.h
> > +++ b/drivers/gpu/drm/xe/xe_bo_types.h
> > @@ -86,7 +86,7 @@ struct xe_bo {
> >     u16 cpu_caching;
> >     /** @devmem_allocation: SVM device memory allocation */
> > -   struct drm_gpusvm_devmem devmem_allocation;
> > +   struct drm_pagemap_devmem devmem_allocation;
> >     /** @vram_userfault_link: Link into @mem_access.vram_userfault.list */
> >             struct list_head vram_userfault_link;
> > diff --git a/drivers/gpu/drm/xe/xe_device_types.h 
> > b/drivers/gpu/drm/xe/xe_device_types.h
> > index ac27389ccb8b..4a907231c0fc 100644
> > --- a/drivers/gpu/drm/xe/xe_device_types.h
> > +++ b/drivers/gpu/drm/xe/xe_device_types.h
> > @@ -105,7 +105,7 @@ struct xe_vram_region {
> >     void __iomem *mapping;
> >     /** @ttm: VRAM TTM manager */
> >     struct xe_ttm_vram_mgr ttm;
> > -#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)
> > +#if IS_ENABLED(CONFIG_DRM_XE_PAGEMAP)
> >     /** @pagemap: Used to remap device memory as ZONE_DEVICE */
> >     struct dev_pagemap pagemap;
> >     /**
> > diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> > index 83c63fd7b481..51b01a11a0cf 100644
> > --- a/drivers/gpu/drm/xe/xe_svm.c
> > +++ b/drivers/gpu/drm/xe/xe_svm.c
> > @@ -329,7 +329,7 @@ static void xe_svm_garbage_collector_work_func(struct 
> > work_struct *w)
> >     up_write(&vm->lock);
> >   }
> > -#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)
> > +#if IS_ENABLED(CONFIG_DRM_XE_PAGEMAP)
> >   static struct xe_vram_region *page_to_vr(struct page *page)
> >   {
> > @@ -517,12 +517,12 @@ static int xe_svm_copy_to_ram(struct page **pages, 
> > dma_addr_t *dma_addr,
> >     return xe_svm_copy(pages, dma_addr, npages, XE_SVM_COPY_TO_SRAM);
> >   }
> > -static struct xe_bo *to_xe_bo(struct drm_gpusvm_devmem *devmem_allocation)
> > +static struct xe_bo *to_xe_bo(struct drm_pagemap_devmem *devmem_allocation)
> >   {
> >     return container_of(devmem_allocation, struct xe_bo, devmem_allocation);
> >   }
> > -static void xe_svm_devmem_release(struct drm_gpusvm_devmem 
> > *devmem_allocation)
> > +static void xe_svm_devmem_release(struct drm_pagemap_devmem 
> > *devmem_allocation)
> >   {
> >     struct xe_bo *bo = to_xe_bo(devmem_allocation);
> > @@ -539,7 +539,7 @@ static struct drm_buddy *tile_to_buddy(struct xe_tile 
> > *tile)
> >     return &tile->mem.vram.ttm.mm;
> >   }
> > -static int xe_svm_populate_devmem_pfn(struct drm_gpusvm_devmem 
> > *devmem_allocation,
> > +static int xe_svm_populate_devmem_pfn(struct drm_pagemap_devmem 
> > *devmem_allocation,
> >                                   unsigned long npages, unsigned long *pfn)
> >   {
> >     struct xe_bo *bo = to_xe_bo(devmem_allocation);
> > @@ -562,7 +562,7 @@ static int xe_svm_populate_devmem_pfn(struct 
> > drm_gpusvm_devmem *devmem_allocatio
> >     return 0;
> >   }
> > -static const struct drm_gpusvm_devmem_ops gpusvm_devmem_ops = {
> > +static const struct drm_pagemap_devmem_ops dpagemap_devmem_ops = {
> >     .devmem_release = xe_svm_devmem_release,
> >     .populate_devmem_pfn = xe_svm_populate_devmem_pfn,
> >     .copy_to_devmem = xe_svm_copy_to_devmem,
> > @@ -714,7 +714,7 @@ u64 xe_svm_find_vma_start(struct xe_vm *vm, u64 start, 
> > u64 end, struct xe_vma *v
> >                                      min(end, xe_vma_end(vma)));
> >   }
> > -#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)
> > +#if IS_ENABLED(CONFIG_DRM_XE_PAGEMAP)
> >   static struct xe_vram_region *tile_to_vr(struct xe_tile *tile)
> >   {
> >     return &tile->mem.vram;
> > @@ -742,6 +742,9 @@ int xe_svm_alloc_vram(struct xe_vm *vm, struct xe_tile 
> > *tile,
> >     ktime_t end = 0;
> >     int err;
> > +   if (!range->base.flags.migrate_devmem)
> > +           return -EINVAL;
> > +
> >     range_debug(range, "ALLOCATE VRAM");
> >     if (!mmget_not_zero(mm))
> > @@ -761,19 +764,23 @@ int xe_svm_alloc_vram(struct xe_vm *vm, struct 
> > xe_tile *tile,
> >             goto unlock;
> >     }
> > -   drm_gpusvm_devmem_init(&bo->devmem_allocation,
> > -                          vm->xe->drm.dev, mm,
> > -                          &gpusvm_devmem_ops,
> > -                          &tile->mem.vram.dpagemap,
> > -                          xe_svm_range_size(range));
> > +   drm_pagemap_devmem_init(&bo->devmem_allocation,
> > +                           vm->xe->drm.dev, mm,
> > +                           &dpagemap_devmem_ops,
> > +                           &tile->mem.vram.dpagemap,
> > +                           xe_svm_range_size(range));
> >     blocks = &to_xe_ttm_vram_mgr_resource(bo->ttm.resource)->blocks;
> >     list_for_each_entry(block, blocks, link)
> >             block->private = vr;
> >     xe_bo_get(bo);
> > -   err = drm_gpusvm_migrate_to_devmem(&vm->svm.gpusvm, &range->base,
> > -                                      &bo->devmem_allocation, ctx);
> > +   err = drm_pagemap_migrate_to_devmem(&bo->devmem_allocation,
> > +                                       mm,
> > +                                       xe_svm_range_start(range),
> > +                                       xe_svm_range_end(range),
> > +                                       ctx->timeslice_ms,
> > +                                       xe_svm_devm_owner(vm->xe));
> >     if (err)
> >             xe_svm_devmem_release(&bo->devmem_allocation);
> > @@ -848,13 +855,13 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct 
> > xe_vma *vma,
> >     struct drm_gpusvm_ctx ctx = {
> >             .read_only = xe_vma_read_only(vma),
> >             .devmem_possible = IS_DGFX(vm->xe) &&
> > -                   IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR),
> > +                   IS_ENABLED(CONFIG_DRM_XE_PAGEMAP),
> >             .check_pages_threshold = IS_DGFX(vm->xe) &&
> > -                   IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR) ? SZ_64K : 0,
> > +                   IS_ENABLED(CONFIG_DRM_XE_PAGEMAP) ? SZ_64K : 0,
> >             .devmem_only = atomic && IS_DGFX(vm->xe) &&
> > -                   IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR),
> > +                   IS_ENABLED(CONFIG_DRM_XE_PAGEMAP),
> >             .timeslice_ms = atomic && IS_DGFX(vm->xe) &&
> > -                   IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR) ?
> > +                   IS_ENABLED(CONFIG_DRM_XE_PAGEMAP) ?
> >                     vm->xe->atomic_svm_timeslice_ms : 0,
> >     };
> >     struct xe_svm_range *range;
> > @@ -992,7 +999,7 @@ bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, 
> > u64 end)
> >    */
> >   int xe_svm_bo_evict(struct xe_bo *bo)
> >   {
> > -   return drm_gpusvm_evict_to_ram(&bo->devmem_allocation);
> > +   return drm_pagemap_evict_to_ram(&bo->devmem_allocation);
> >   }
> >   /**
> > @@ -1045,7 +1052,7 @@ int xe_svm_range_get_pages(struct xe_vm *vm, struct 
> > xe_svm_range *range,
> >     return err;
> >   }
> > -#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)
> > +#if IS_ENABLED(CONFIG_DRM_XE_PAGEMAP)
> >   static struct drm_pagemap_device_addr
> >   xe_drm_pagemap_device_map(struct drm_pagemap *dpagemap,
> > @@ -1102,7 +1109,7 @@ int xe_devm_add(struct xe_tile *tile, struct 
> > xe_vram_region *vr)
> >     vr->pagemap.range.start = res->start;
> >     vr->pagemap.range.end = res->end;
> >     vr->pagemap.nr_range = 1;
> > -   vr->pagemap.ops = drm_gpusvm_pagemap_ops_get();
> > +   vr->pagemap.ops = drm_pagemap_pagemap_ops_get();
> >     vr->pagemap.owner = xe_svm_devm_owner(xe);
> >     addr = devm_memremap_pages(dev, &vr->pagemap);
> > diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
> > index 6a5156476bf4..4aedc5423aff 100644
> > --- a/include/drm/drm_gpusvm.h
> > +++ b/include/drm/drm_gpusvm.h
> > @@ -16,91 +16,9 @@ struct drm_gpusvm;
> >   struct drm_gpusvm_notifier;
> >   struct drm_gpusvm_ops;
> >   struct drm_gpusvm_range;
> > -struct drm_gpusvm_devmem;
> >   struct drm_pagemap;
> >   struct drm_pagemap_device_addr;
> > -/**
> > - * struct drm_gpusvm_devmem_ops - Operations structure for GPU SVM device 
> > memory
> > - *
> > - * This structure defines the operations for GPU Shared Virtual Memory 
> > (SVM)
> > - * device memory. These operations are provided by the GPU driver to 
> > manage device memory
> > - * allocations and perform operations such as migration between device 
> > memory and system
> > - * RAM.
> > - */
> > -struct drm_gpusvm_devmem_ops {
> > -   /**
> > -    * @devmem_release: Release device memory allocation (optional)
> > -    * @devmem_allocation: device memory allocation
> > -    *
> > -    * Release device memory allocation and drop a reference to device
> > -    * memory allocation.
> > -    */
> > -   void (*devmem_release)(struct drm_gpusvm_devmem *devmem_allocation);
> > -
> > -   /**
> > -    * @populate_devmem_pfn: Populate device memory PFN (required for 
> > migration)
> > -    * @devmem_allocation: device memory allocation
> > -    * @npages: Number of pages to populate
> > -    * @pfn: Array of page frame numbers to populate
> > -    *
> > -    * Populate device memory page frame numbers (PFN).
> > -    *
> > -    * Return: 0 on success, a negative error code on failure.
> > -    */
> > -   int (*populate_devmem_pfn)(struct drm_gpusvm_devmem *devmem_allocation,
> > -                              unsigned long npages, unsigned long *pfn);
> > -
> > -   /**
> > -    * @copy_to_devmem: Copy to device memory (required for migration)
> > -    * @pages: Pointer to array of device memory pages (destination)
> > -    * @dma_addr: Pointer to array of DMA addresses (source)
> > -    * @npages: Number of pages to copy
> > -    *
> > -    * Copy pages to device memory.
> > -    *
> > -    * Return: 0 on success, a negative error code on failure.
> > -    */
> > -   int (*copy_to_devmem)(struct page **pages,
> > -                         dma_addr_t *dma_addr,
> > -                         unsigned long npages);
> > -
> > -   /**
> > -    * @copy_to_ram: Copy to system RAM (required for migration)
> > -    * @pages: Pointer to array of device memory pages (source)
> > -    * @dma_addr: Pointer to array of DMA addresses (destination)
> > -    * @npages: Number of pages to copy
> > -    *
> > -    * Copy pages to system RAM.
> > -    *
> > -    * Return: 0 on success, a negative error code on failure.
> > -    */
> > -   int (*copy_to_ram)(struct page **pages,
> > -                      dma_addr_t *dma_addr,
> > -                      unsigned long npages);
> > -};
> > -
> > -/**
> > - * struct drm_gpusvm_devmem - Structure representing a GPU SVM device 
> > memory allocation
> > - *
> > - * @dev: Pointer to the device structure which device memory allocation 
> > belongs to
> > - * @mm: Pointer to the mm_struct for the address space
> > - * @detached: device memory allocations is detached from device pages
> > - * @ops: Pointer to the operations structure for GPU SVM device memory
> > - * @dpagemap: The struct drm_pagemap of the pages this allocation belongs 
> > to.
> > - * @size: Size of device memory allocation
> > - * @timeslice_expiration: Timeslice expiration in jiffies
> > - */
> > -struct drm_gpusvm_devmem {
> > -   struct device *dev;
> > -   struct mm_struct *mm;
> > -   struct completion detached;
> > -   const struct drm_gpusvm_devmem_ops *ops;
> > -   struct drm_pagemap *dpagemap;
> > -   size_t size;
> > -   u64 timeslice_expiration;
> > -};
> > -
> >   /**
> >    * struct drm_gpusvm_ops - Operations structure for GPU SVM
> >    *
> > @@ -361,15 +279,6 @@ void drm_gpusvm_range_unmap_pages(struct drm_gpusvm 
> > *gpusvm,
> >                               struct drm_gpusvm_range *range,
> >                               const struct drm_gpusvm_ctx *ctx);
> > -int drm_gpusvm_migrate_to_devmem(struct drm_gpusvm *gpusvm,
> > -                            struct drm_gpusvm_range *range,
> > -                            struct drm_gpusvm_devmem *devmem_allocation,
> > -                            const struct drm_gpusvm_ctx *ctx);
> > -
> > -int drm_gpusvm_evict_to_ram(struct drm_gpusvm_devmem *devmem_allocation);
> > -
> > -const struct dev_pagemap_ops *drm_gpusvm_pagemap_ops_get(void);
> > -
> >   bool drm_gpusvm_has_mapping(struct drm_gpusvm *gpusvm, unsigned long 
> > start,
> >                         unsigned long end);
> > @@ -380,11 +289,6 @@ drm_gpusvm_range_find(struct drm_gpusvm_notifier 
> > *notifier, unsigned long start,
> >   void drm_gpusvm_range_set_unmapped(struct drm_gpusvm_range *range,
> >                                const struct mmu_notifier_range *mmu_range);
> > -void drm_gpusvm_devmem_init(struct drm_gpusvm_devmem *devmem_allocation,
> > -                       struct device *dev, struct mm_struct *mm,
> > -                       const struct drm_gpusvm_devmem_ops *ops,
> > -                       struct drm_pagemap *dpagemap, size_t size);
> > -
> >   #ifdef CONFIG_LOCKDEP
> >   /**
> >    * drm_gpusvm_driver_set_lock() - Set the lock protecting accesses to GPU 
> > SVM
> > diff --git a/include/drm/drm_pagemap.h b/include/drm/drm_pagemap.h
> > index 202c157ff4d7..dabc9c365df4 100644
> > --- a/include/drm/drm_pagemap.h
> > +++ b/include/drm/drm_pagemap.h
> > @@ -7,6 +7,7 @@
> >   #include <linux/types.h>
> >   struct drm_pagemap;
> > +struct drm_pagemap_zdd;
> >   struct device;
> >   /**
> > @@ -104,4 +105,104 @@ struct drm_pagemap {
> >     struct device *dev;
> >   };
> > +struct drm_pagemap_devmem;
> > +
> > +/**
> > + * struct drm_pagemap_devmem_ops - Operations structure for GPU SVM device 
> > memory
> > + *
> > + * This structure defines the operations for GPU Shared Virtual Memory 
> > (SVM)
> > + * device memory. These operations are provided by the GPU driver to 
> > manage device memory
> > + * allocations and perform operations such as migration between device 
> > memory and system
> > + * RAM.
> > + */
> > +struct drm_pagemap_devmem_ops {
> > +   /**
> > +    * @devmem_release: Release device memory allocation (optional)
> > +    * @devmem_allocation: device memory allocation
> > +    *
> > +    * Release device memory allocation and drop a reference to device
> > +    * memory allocation.
> > +    */
> > +   void (*devmem_release)(struct drm_pagemap_devmem *devmem_allocation);
> > +
> > +   /**
> > +    * @populate_devmem_pfn: Populate device memory PFN (required for 
> > migration)
> > +    * @devmem_allocation: device memory allocation
> > +    * @npages: Number of pages to populate
> > +    * @pfn: Array of page frame numbers to populate
> > +    *
> > +    * Populate device memory page frame numbers (PFN).
> > +    *
> > +    * Return: 0 on success, a negative error code on failure.
> > +    */
> > +   int (*populate_devmem_pfn)(struct drm_pagemap_devmem *devmem_allocation,
> > +                              unsigned long npages, unsigned long *pfn);
> > +
> > +   /**
> > +    * @copy_to_devmem: Copy to device memory (required for migration)
> > +    * @pages: Pointer to array of device memory pages (destination)
> > +    * @dma_addr: Pointer to array of DMA addresses (source)
> > +    * @npages: Number of pages to copy
> > +    *
> > +    * Copy pages to device memory.
> > +    *
> > +    * Return: 0 on success, a negative error code on failure.
> > +    */
> > +   int (*copy_to_devmem)(struct page **pages,
> > +                         dma_addr_t *dma_addr,
> > +                         unsigned long npages);
> > +
> > +   /**
> > +    * @copy_to_ram: Copy to system RAM (required for migration)
> > +    * @pages: Pointer to array of device memory pages (source)
> > +    * @dma_addr: Pointer to array of DMA addresses (destination)
> > +    * @npages: Number of pages to copy
> > +    *
> > +    * Copy pages to system RAM.
> > +    *
> > +    * Return: 0 on success, a negative error code on failure.
> > +    */
> > +   int (*copy_to_ram)(struct page **pages,
> > +                      dma_addr_t *dma_addr,
> > +                      unsigned long npages);
> > +};
> > +
> > +/**
> > + * struct drm_pagemap_devmem - Structure representing a GPU SVM device 
> > memory allocation
> > + *
> > + * @dev: Pointer to the device structure which device memory allocation 
> > belongs to
> > + * @mm: Pointer to the mm_struct for the address space
> > + * @detached: device memory allocations is detached from device pages
> > + * @ops: Pointer to the operations structure for GPU SVM device memory
> > + * @dpagemap: The struct drm_pagemap of the pages this allocation belongs 
> > to.
> > + * @size: Size of device memory allocation
> > + * @timeslice_expiration: Timeslice expiration in jiffies
> > + */
> > +struct drm_pagemap_devmem {
> > +   struct device *dev;
> > +   struct mm_struct *mm;
> > +   struct completion detached;
> > +   const struct drm_pagemap_devmem_ops *ops;
> > +   struct drm_pagemap *dpagemap;
> > +   size_t size;
> > +   u64 timeslice_expiration;
> > +};
> > +
> > +int drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem 
> > *devmem_allocation,
> > +                             struct mm_struct *mm,
> > +                             unsigned long start, unsigned long end,
> > +                             unsigned long timeslice_ms,
> > +                             void *pgmap_owner);
> > +
> > +int drm_pagemap_evict_to_ram(struct drm_pagemap_devmem *devmem_allocation);
> > +
> > +const struct dev_pagemap_ops *drm_pagemap_pagemap_ops_get(void);
> > +
> > +struct drm_pagemap *drm_pagemap_page_to_dpagemap(struct page *page);
> > +
> > +void drm_pagemap_devmem_init(struct drm_pagemap_devmem *devmem_allocation,
> > +                        struct device *dev, struct mm_struct *mm,
> > +                        const struct drm_pagemap_devmem_ops *ops,
> > +                        struct drm_pagemap *dpagemap, size_t size);
> 
> LGTM
> Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimi...@intel.com>> +
> >   #endif
> 

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