Re: [PATCH v3 19/30] drm/xe: Add SVM device memory mirroring

[Matthew Brost <matthew.brost@intel.com>]

On Sat, Dec 21, 2024 at 12:09:55AM +0530, Ghimiray, Himal Prasad wrote:
> 
> 
> On 18-12-2024 05:03, 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
> > 
> > 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>
> > ---
> >   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 3a08e16bfada..1989c99a9f5a 100644
> > --- a/drivers/gpu/drm/xe/Kconfig
> > +++ b/drivers/gpu/drm/xe/Kconfig
> > @@ -60,6 +60,15 @@ config DRM_XE_DISPLAY
> >   	help
> >   	  Disable this option only if you want to compile out display support.
> > +config CONFIG_XE_DEVMEM_MIRROR
> 
> 
> %s/CONFIG_XE_DEVMEM_MIRROR/XE_DEVMEM_MIRROR
> 

Yep, missed this. This version is broken with proper Kconfig enabled
too. Working on fixing this up now.

Matt

> 
> > +	bool "Enable device memory mirror"
> > +	depends on DRM_XE
> > +	select CONFIG_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 8a7b15972413..b949a960cebb 100644
> > --- a/drivers/gpu/drm/xe/xe_device_types.h
> > +++ b/drivers/gpu/drm/xe/xe_device_types.h
> > @@ -102,6 +102,14 @@ 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 3cbf29732249..2860e54bb035 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)
> >   {
> > @@ -306,8 +311,8 @@ 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;
> > @@ -442,3 +447,56 @@ 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_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 %d\n",
> > +				tile->id, 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 ddce1069ba1e..85832e6ed3f5 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 07cf7cfe4abd..bbb430392dfb 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);
> > @@ -176,6 +178,9 @@ 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;
>