Re: [PATCH v5 21/32] drm/xe: Add SVM device memory mirroring

["Ghimiray, Himal Prasad" <himal.prasad.ghimiray@intel.com>]

On 13-02-2025 07:41, Matthew Brost wrote:
> 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)
> v5:
>   - s/xe_mem_region/xe_vram_region (Rebase)
> 
> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
> Signed-off-by: Oak Zeng <oak.zeng@intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.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 6a41f608a7a1..00873d80b10d 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -106,6 +106,14 @@ struct xe_vram_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;
>   	/** @ttm: VRAM TTM manager */
>   	struct xe_ttm_vram_mgr ttm;
>   };
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index 7b1076c184e3..b1947c75c249 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -29,6 +29,11 @@ static unsigned long xe_svm_range_end(struct xe_svm_range *range)
>   	return drm_gpusvm_range_end(&range->base);
>   }
>   
> +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)
>   {
> @@ -317,8 +322,8 @@ 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;
> @@ -453,3 +458,56 @@ 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
> + * @vr: vram 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_vram_region *vr)
> +{
> +	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,
> +					   vr->usable_size);
> +	if (IS_ERR(res)) {
> +		ret = PTR_ERR(res);
> +		return ret;
> +	}
> +
> +	vr->pagemap.type = MEMORY_DEVICE_PRIVATE;
> +	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.owner = xe_svm_devm_owner(xe);
> +	addr = devm_memremap_pages(dev, &vr->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;
> +	}
> +	vr->hpa_base = res->start;
> +
> +	drm_info(&xe->drm, "Added tile %d memory [%llx-%llx] to devm, remapped to %pr\n",
> +		 tile->id, vr->io_start, vr->io_start + vr->usable_size, res);
> +	return 0;
> +}
> +#else
> +int xe_devm_add(struct xe_tile *tile, struct xe_vram_region *vr)
> +{
> +	return 0;
> +}
> +#endif
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> index 50d47024d2db..0fa525d34987 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_vram_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_vram_region *vr);
> +
>   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 d9a7a04ff652..51cda137cfbc 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"
> @@ -160,6 +161,7 @@ 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);
> @@ -168,6 +170,9 @@ 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);
> +

Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

>   	err = xe_tile_sysfs_init(tile);
>   
>   	return 0;