Re: [PATCH v1 1/7] drm/xe/sa: Avoid caching GGTT address within the manager

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

On Wed, May 14, 2025 at 12:49:46AM +0200, Tomasz Lis wrote:
> Non-virtualized resources require fixups after SRIOV VF migration.
> Caching GGTT references rather than re-computing them from the
> underlying Buffer Object is something we want to avoid, as such
> code would require additional fixup step and additional locking
> around all the places where the address is accessed.
> 
> This change removes the cached address, and introduces a function
> which recomputes and returns the address instead.
> 
> Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_debugfs.c | 3 ++-
>  drivers/gpu/drm/xe/xe_guc_buf.c    | 2 +-
>  drivers/gpu/drm/xe/xe_sa.c         | 1 -
>  drivers/gpu/drm/xe/xe_sa.h         | 8 +++++++-
>  drivers/gpu/drm/xe/xe_sa_types.h   | 1 -
>  5 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_debugfs.c b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> index 119a55bb7580..8aa84050c18b 100644
> --- a/drivers/gpu/drm/xe/xe_gt_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> @@ -29,6 +29,7 @@
>  #include "xe_pm.h"
>  #include "xe_reg_sr.h"
>  #include "xe_reg_whitelist.h"
> +#include "xe_sa.h"
>  #include "xe_sriov.h"
>  #include "xe_tuning.h"
>  #include "xe_uc_debugfs.h"
> @@ -146,7 +147,7 @@ static int sa_info(struct xe_gt *gt, struct drm_printer *p)
>  

Drive by comment - on devices which support faults we have 2 SA pools.

We should probably print both SA on those devices.

Matt

>  	xe_pm_runtime_get(gt_to_xe(gt));
>  	drm_suballoc_dump_debug_info(&tile->mem.kernel_bb_pool->base, p,
> -				     tile->mem.kernel_bb_pool->gpu_addr);
> +				     xe_sa_bo_manager_gpu_addr(tile->mem.kernel_bb_pool));
>  	xe_pm_runtime_put(gt_to_xe(gt));
>  
>  	return 0;
> diff --git a/drivers/gpu/drm/xe/xe_guc_buf.c b/drivers/gpu/drm/xe/xe_guc_buf.c
> index 0193c94dd6a0..c459c71a3510 100644
> --- a/drivers/gpu/drm/xe/xe_guc_buf.c
> +++ b/drivers/gpu/drm/xe/xe_guc_buf.c
> @@ -168,7 +168,7 @@ u64 xe_guc_cache_gpu_addr_from_ptr(struct xe_guc_buf_cache *cache, const void *p
>  	if (offset < 0 || offset + size > cache->sam->base.size)
>  		return 0;
>  
> -	return cache->sam->gpu_addr + offset;
> +	return xe_sa_bo_manager_gpu_addr(cache->sam) + offset;
>  }
>  
>  #if IS_BUILTIN(CONFIG_DRM_XE_KUNIT_TEST)
> diff --git a/drivers/gpu/drm/xe/xe_sa.c b/drivers/gpu/drm/xe/xe_sa.c
> index 1d43e183ca21..fedd017d6dd3 100644
> --- a/drivers/gpu/drm/xe/xe_sa.c
> +++ b/drivers/gpu/drm/xe/xe_sa.c
> @@ -69,7 +69,6 @@ struct xe_sa_manager *__xe_sa_bo_manager_init(struct xe_tile *tile, u32 size, u3
>  	}
>  	sa_manager->bo = bo;
>  	sa_manager->is_iomem = bo->vmap.is_iomem;
> -	sa_manager->gpu_addr = xe_bo_ggtt_addr(bo);
>  
>  	if (bo->vmap.is_iomem) {
>  		sa_manager->cpu_ptr = kvzalloc(managed_size, GFP_KERNEL);
> diff --git a/drivers/gpu/drm/xe/xe_sa.h b/drivers/gpu/drm/xe/xe_sa.h
> index 1170ee5a81a8..614d858b2183 100644
> --- a/drivers/gpu/drm/xe/xe_sa.h
> +++ b/drivers/gpu/drm/xe/xe_sa.h
> @@ -7,6 +7,7 @@
>  
>  #include <linux/sizes.h>
>  #include <linux/types.h>
> +#include "xe_bo.h"
>  #include "xe_sa_types.h"
>  
>  struct dma_fence;
> @@ -43,9 +44,14 @@ to_xe_sa_manager(struct drm_suballoc_manager *mng)
>  	return container_of(mng, struct xe_sa_manager, base);
>  }
>  
> +static inline u64 xe_sa_bo_manager_gpu_addr(struct xe_sa_manager *sa_manager)
> +{
> +	return xe_bo_ggtt_addr(sa_manager->bo);
> +}
> +
>  static inline u64 xe_sa_bo_gpu_addr(struct drm_suballoc *sa)
>  {
> -	return to_xe_sa_manager(sa->manager)->gpu_addr +
> +	return xe_sa_bo_manager_gpu_addr(to_xe_sa_manager(sa->manager)) +
>  		drm_suballoc_soffset(sa);
>  }
>  
> diff --git a/drivers/gpu/drm/xe/xe_sa_types.h b/drivers/gpu/drm/xe/xe_sa_types.h
> index 2b070ff1292e..cb7238799dcb 100644
> --- a/drivers/gpu/drm/xe/xe_sa_types.h
> +++ b/drivers/gpu/drm/xe/xe_sa_types.h
> @@ -12,7 +12,6 @@ struct xe_bo;
>  struct xe_sa_manager {
>  	struct drm_suballoc_manager base;
>  	struct xe_bo *bo;
> -	u64 gpu_addr;
>  	void *cpu_ptr;
>  	bool is_iomem;
>  };
> -- 
> 2.25.1
>