Re: [PATCH 01/10] drm/amdkfd: device pgmap owner at the svm migrate init

[Felix Kuehling <felix.kuehling@amd.com>]

On 2021-06-21 12:04 p.m., Alex Sierra wrote:
> pgmap owner member at the svm migrate init could be referenced
> to either adev or hive, depending on device topology.

The reasoning for this change is, that GPUs in the same XGMI hive have 
direct access to all members' VRAM. When mapping memory to a GPU, we 
don't need hmm_range_fault to fault device-private pages in the same 
hive back to the host. Identifying the page owner as the hive, rather 
than the individual GPU, accomplishes this.

With this explanation in the commit description, the patch is

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>

>
> Signed-off-by: Alex Sierra <alex.sierra@amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 6 +++---
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.h     | 3 +++
>   2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> index fd8f544f0de2..11f7f590c6ec 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> @@ -426,7 +426,7 @@ svm_migrate_vma_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
>   	migrate.start = start;
>   	migrate.end = end;
>   	migrate.flags = MIGRATE_VMA_SELECT_SYSTEM;
> -	migrate.pgmap_owner = adev;
> +	migrate.pgmap_owner = SVM_ADEV_PGMAP_OWNER(adev);
>   
>   	size = 2 * sizeof(*migrate.src) + sizeof(uint64_t) + sizeof(dma_addr_t);
>   	size *= npages;
> @@ -641,7 +641,7 @@ svm_migrate_vma_to_ram(struct amdgpu_device *adev, struct svm_range *prange,
>   	migrate.start = start;
>   	migrate.end = end;
>   	migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
> -	migrate.pgmap_owner = adev;
> +	migrate.pgmap_owner = SVM_ADEV_PGMAP_OWNER(adev);
>   
>   	size = 2 * sizeof(*migrate.src) + sizeof(uint64_t) + sizeof(dma_addr_t);
>   	size *= npages;
> @@ -907,7 +907,7 @@ int svm_migrate_init(struct amdgpu_device *adev)
>   	pgmap->range.start = res->start;
>   	pgmap->range.end = res->end;
>   	pgmap->ops = &svm_migrate_pgmap_ops;
> -	pgmap->owner = adev;
> +	pgmap->owner = SVM_ADEV_PGMAP_OWNER(adev);
>   	pgmap->flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
>   	r = devm_memremap_pages(adev->dev, pgmap);
>   	if (IS_ERR(r)) {
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
> index 573f984b81fe..4297250f259d 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
> @@ -35,6 +35,9 @@
>   #include "amdgpu.h"
>   #include "kfd_priv.h"
>   
> +#define SVM_ADEV_PGMAP_OWNER(adev)\
> +			((adev)->hive ? (void *)(adev)->hive : (void *)(adev))
> +
>   struct svm_range_bo {
>   	struct amdgpu_bo		*bo;
>   	struct kref			kref;
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