Re: [PATCH v6 02/13] drm/amdkfd: Use migrate pfns internally

David Hildenbrand (Arm)
2026-03-03T16:41:08Z

On 2/2/26 12:36, Jordan Niethe wrote:
> A future change will remove device private pages from the physical
> address space. This will mean that device private pages no longer have a
> pfn.
>
> A MIGRATE_PFN flag will be introduced that distinguishes between mpfns
> that contain a pfn vs an offset into device private memory.
>
> Replace usages of pfns and page_to_pfn() with mpfns and
> migrate_pfn_to_page() to prepare for handling this distinction. This
> will assist in continuing to use the same code paths for both
> MEMORY_DEVICE_PRIVATE and MEMORY_DEVICE_COHERENT devices.
>
> Acked-by: Balbir Singh <balbirs@nvidia.com>
> Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
> Signed-off-by: Jordan Niethe <jniethe@nvidia.com>
> ---
> v2:
> - New to series
> v3:
> - No change
> v4:
> - No change
> ---
> drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 15 +++++++--------
> drivers/gpu/drm/amd/amdkfd/kfd_migrate.h | 2 +-
> 2 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> index 297fa108ccf9..b6075a2808c2 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> @@ -210,17 +210,17 @@ svm_migrate_copy_done(struct amdgpu_device *adev, struct dma_fence *mfence)
> }
>
> unsigned long
> -svm_migrate_addr_to_pfn(struct amdgpu_device *adev, unsigned long addr)
> +svm_migrate_addr_to_mpfn(struct amdgpu_device *adev, unsigned long addr)
> {
> - return (addr + adev->kfd.pgmap.range.start) >> PAGE_SHIFT;
> + return migrate_pfn((addr + adev->kfd.pgmap.range.start) >> PAGE_SHIFT);
> }

To make it clearer that the result is a "migrate pfn" I'd call this.

svm_addr_to_migrate_pfn()

Not sure if maintainers have any other preference.

Apart from that LGTM (someone should convert this code to use folios ;) ).

--
Cheers,

David