Add SVM device memory mirroring which enables device pages for
migration. Enabled via CONFIG_XE_DEVMEM_MIRROR Kconfig. Kconfig option
defaults to enabled. If not enabled, SVM will work sans migration and
KMD memory footprint will be less.

v3:
 - Add CONFIG_XE_DEVMEM_MIRROR
v4:
 - Fix Kconfig (Himal)
 - Use %pe to print errors (Thomas)
 - Fix alignment issue (Checkpatch)

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathap...@intel.com>
Signed-off-by: Oak Zeng <oak.z...@intel.com>
Signed-off-by: Matthew Brost <matthew.br...@intel.com>
---
 drivers/gpu/drm/xe/Kconfig           |  9 ++++
 drivers/gpu/drm/xe/xe_device_types.h |  8 ++++
 drivers/gpu/drm/xe/xe_svm.c          | 62 +++++++++++++++++++++++++++-
 drivers/gpu/drm/xe/xe_svm.h          |  3 ++
 drivers/gpu/drm/xe/xe_tile.c         |  5 +++
 5 files changed, 85 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
index 60b922f75001..4bc03d6f6720 100644
--- a/drivers/gpu/drm/xe/Kconfig
+++ b/drivers/gpu/drm/xe/Kconfig
@@ -74,6 +74,15 @@ config DRM_XE_DP_TUNNEL
 
          If in doubt say "Y".
 
+config DRM_XE_DEVMEM_MIRROR
+       bool "Enable device memory mirror"
+       depends on DRM_XE
+       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.
+
 config DRM_XE_FORCE_PROBE
        string "Force probe xe for selected Intel hardware IDs"
        depends on DRM_XE
diff --git a/drivers/gpu/drm/xe/xe_device_types.h 
b/drivers/gpu/drm/xe/xe_device_types.h
index 71151532e28f..da5bf145324b 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -104,6 +104,14 @@ struct xe_mem_region {
        resource_size_t actual_physical_size;
        /** @mapping: pointer to VRAM mappable space */
        void __iomem *mapping;
+       /** @pagemap: Used to remap device memory as ZONE_DEVICE */
+       struct dev_pagemap pagemap;
+       /**
+        * @hpa_base: base host physical address
+        *
+        * This is generated when remap device memory as ZONE_DEVICE
+        */
+       resource_size_t hpa_base;
 };
 
 /**
diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index ee150139470f..985ac20c5b07 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -19,6 +19,11 @@ static struct xe_vm *range_to_vm(struct drm_gpusvm_range *r)
        return gpusvm_to_vm(r->gpusvm);
 }
 
+static void *xe_svm_devm_owner(struct xe_device *xe)
+{
+       return xe;
+}
+
 static struct drm_gpusvm_range *
 xe_svm_range_alloc(struct drm_gpusvm *gpusvm)
 {
@@ -307,8 +312,8 @@ int xe_svm_init(struct xe_vm *vm)
                  xe_svm_garbage_collector_work_func);
 
        err = drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM", &vm->xe->drm,
-                             current->mm, NULL, 0, vm->size,
-                             SZ_512M, &gpusvm_ops, fault_chunk_sizes,
+                             current->mm, xe_svm_devm_owner(vm->xe), 0,
+                             vm->size, SZ_512M, &gpusvm_ops, fault_chunk_sizes,
                              ARRAY_SIZE(fault_chunk_sizes));
        if (err)
                return err;
@@ -443,3 +448,56 @@ bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, u64 
end)
 {
        return drm_gpusvm_has_mapping(&vm->svm.gpusvm, start, end);
 }
+
+#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR)
+/**
+ * xe_devm_add: Remap and provide memmap backing for device memory
+ * @tile: tile that the memory region belongs to
+ * @mr: memory region to remap
+ *
+ * This remap device memory to host physical address space and create
+ * struct page to back device memory
+ *
+ * Return: 0 on success standard error code otherwise
+ */
+int xe_devm_add(struct xe_tile *tile, struct xe_mem_region *mr)
+{
+       struct xe_device *xe = tile_to_xe(tile);
+       struct device *dev = &to_pci_dev(xe->drm.dev)->dev;
+       struct resource *res;
+       void *addr;
+       int ret;
+
+       res = devm_request_free_mem_region(dev, &iomem_resource,
+                                          mr->usable_size);
+       if (IS_ERR(res)) {
+               ret = PTR_ERR(res);
+               return ret;
+       }
+
+       mr->pagemap.type = MEMORY_DEVICE_PRIVATE;
+       mr->pagemap.range.start = res->start;
+       mr->pagemap.range.end = res->end;
+       mr->pagemap.nr_range = 1;
+       mr->pagemap.ops = drm_gpusvm_pagemap_ops_get();
+       mr->pagemap.owner = xe_svm_devm_owner(xe);
+       addr = devm_memremap_pages(dev, &mr->pagemap);
+       if (IS_ERR(addr)) {
+               devm_release_mem_region(dev, res->start, resource_size(res));
+               ret = PTR_ERR(addr);
+               drm_err(&xe->drm, "Failed to remap tile %d memory, errno %pe\n",
+                       tile->id, ERR_PTR(ret));
+               return ret;
+       }
+       mr->hpa_base = res->start;
+
+       drm_info(&xe->drm, "Added tile %d memory [%llx-%llx] to devm, remapped 
to %pr\n",
+                tile->id, mr->io_start, mr->io_start + mr->usable_size, res);
+       return 0;
+}
+#else
+int xe_devm_add(struct xe_tile *tile, struct xe_mem_region *mr)
+{
+       return 0;
+}
+#endif
diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
index b181c174ca61..63daffdfdbf6 100644
--- a/drivers/gpu/drm/xe/xe_svm.h
+++ b/drivers/gpu/drm/xe/xe_svm.h
@@ -11,6 +11,7 @@
 
 #define XE_INTERCONNECT_VRAM DRM_INTERCONNECT_DRIVER
 
+struct xe_mem_region;
 struct xe_tile;
 struct xe_vm;
 struct xe_vma;
@@ -36,6 +37,8 @@ struct xe_svm_range {
        u8 tile_invalidated;
 };
 
+int xe_devm_add(struct xe_tile *tile, struct xe_mem_region *mr);
+
 int xe_svm_init(struct xe_vm *vm);
 
 void xe_svm_fini(struct xe_vm *vm);
diff --git a/drivers/gpu/drm/xe/xe_tile.c b/drivers/gpu/drm/xe/xe_tile.c
index 2825553b568f..6c80a637ded5 100644
--- a/drivers/gpu/drm/xe/xe_tile.c
+++ b/drivers/gpu/drm/xe/xe_tile.c
@@ -13,6 +13,7 @@
 #include "xe_migrate.h"
 #include "xe_pcode.h"
 #include "xe_sa.h"
+#include "xe_svm.h"
 #include "xe_tile.h"
 #include "xe_tile_sysfs.h"
 #include "xe_ttm_vram_mgr.h"
@@ -164,6 +165,7 @@ static int tile_ttm_mgr_init(struct xe_tile *tile)
  */
 int xe_tile_init_noalloc(struct xe_tile *tile)
 {
+       struct xe_device *xe = tile_to_xe(tile);
        int err;
 
        err = tile_ttm_mgr_init(tile);
@@ -172,6 +174,9 @@ int xe_tile_init_noalloc(struct xe_tile *tile)
 
        xe_wa_apply_tile_workarounds(tile);
 
+       if (xe->info.has_usm && IS_DGFX(xe))
+               xe_devm_add(tile, &tile->mem.vram);
+
        err = xe_tile_sysfs_init(tile);
 
        return 0;
-- 
2.34.1

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