On Wed, Aug 20, 2025 at 8:28 AM Srinivasan Shanmugam
<srinivasan.shanmu...@amd.com> wrote:
>
> Implement TTM-level behavior for AMDGPU_PL_MMIO_REMAP so it behaves
> as a CPU-visible IO page:
>
> * amdgpu_evict_flags(): mark as unmovable
> * amdgpu_res_cpu_visible(): consider CPU-visible
> * amdgpu_bo_move(): use null move when src/dst is MMIO_REMAP
> * amdgpu_ttm_io_mem_reserve(): program bus.offset/is_iomem/caching using
> the device's mmio_remap_* metadata
> * amdgpu_ttm_io_mem_pfn(): return PFN for the remapped HDP page
> * amdgpu_ttm_tt_pde_flags(): set AMDGPU_PTE_SYSTEM for this mem type
>
> Cc: Christian König <christian.koe...@amd.com>
> Cc: Alex Deucher <alexander.deuc...@amd.com>
> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmu...@amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 26 +++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 27ab4e754b2a..157a5416a826 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -123,6 +123,7 @@ static void amdgpu_evict_flags(struct ttm_buffer_object
> *bo,
> case AMDGPU_PL_GWS:
> case AMDGPU_PL_OA:
> case AMDGPU_PL_DOORBELL:
> + case AMDGPU_PL_MMIO_REMAP:
> placement->num_placement = 0;
> return;
>
> @@ -447,7 +448,8 @@ bool amdgpu_res_cpu_visible(struct amdgpu_device *adev,
> return false;
>
> if (res->mem_type == TTM_PL_SYSTEM || res->mem_type == TTM_PL_TT ||
> - res->mem_type == AMDGPU_PL_PREEMPT || res->mem_type ==
> AMDGPU_PL_DOORBELL)
> + res->mem_type == AMDGPU_PL_PREEMPT || res->mem_type ==
> AMDGPU_PL_DOORBELL ||
> + res->mem_type == AMDGPU_PL_MMIO_REMAP)
> return true;
>
> if (res->mem_type != TTM_PL_VRAM)
> @@ -538,10 +540,12 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo,
> bool evict,
> old_mem->mem_type == AMDGPU_PL_GWS ||
> old_mem->mem_type == AMDGPU_PL_OA ||
> old_mem->mem_type == AMDGPU_PL_DOORBELL ||
> + old_mem->mem_type == AMDGPU_PL_MMIO_REMAP ||
> new_mem->mem_type == AMDGPU_PL_GDS ||
> new_mem->mem_type == AMDGPU_PL_GWS ||
> new_mem->mem_type == AMDGPU_PL_OA ||
> - new_mem->mem_type == AMDGPU_PL_DOORBELL) {
> + new_mem->mem_type == AMDGPU_PL_DOORBELL ||
> + new_mem->mem_type == AMDGPU_PL_MMIO_REMAP) {
> /* Nothing to save here */
> amdgpu_bo_move_notify(bo, evict, new_mem);
> ttm_bo_move_null(bo, new_mem);
> @@ -629,6 +633,12 @@ static int amdgpu_ttm_io_mem_reserve(struct ttm_device
> *bdev,
> mem->bus.is_iomem = true;
> mem->bus.caching = ttm_uncached;
> break;
> + case AMDGPU_PL_MMIO_REMAP: /* <=== New HDP domain for remap page */
This comment can be dropped. It's just a remapping range. We've only
used it for the HDP registers, but it could be used for other things
in the future.
> + mem->bus.offset = ((resource_size_t)mem->start <<
> PAGE_SHIFT);
> + mem->bus.offset += adev->mmio_remap_base +
> adev->mmio_remap_offset;
This should be the same as the doorbell handling, just replace
adev->doorbell.base with adev->mmio_remap.base
Alex
> + mem->bus.is_iomem = true;
> + mem->bus.caching = ttm_uncached;
> + break;
> default:
> return -EINVAL;
> }
> @@ -640,12 +650,20 @@ static unsigned long amdgpu_ttm_io_mem_pfn(struct
> ttm_buffer_object *bo,
> {
> struct amdgpu_device *adev = amdgpu_ttm_adev(bo->bdev);
> struct amdgpu_res_cursor cursor;
> + u64 pfn;
>
> amdgpu_res_first(bo->resource, (u64)page_offset << PAGE_SHIFT, 0,
> &cursor);
>
> - if (bo->resource->mem_type == AMDGPU_PL_DOORBELL)
> + if (bo->resource->mem_type == AMDGPU_PL_DOORBELL) {
> return ((uint64_t)(adev->doorbell.base + cursor.start)) >>
> PAGE_SHIFT;
> + } else if (bo->resource->mem_type == AMDGPU_PL_MMIO_REMAP) {
> + /* Return PFN for the remapped HDP page */
> + pfn = (u64)adev->mmio_remap_base +
> + (u64)adev->mmio_remap_offset +
> + (u64)cursor.start;
> + return (unsigned long)(pfn >> PAGE_SHIFT);
> + }
>
> return (adev->gmc.aper_base + cursor.start) >> PAGE_SHIFT;
> }
> @@ -1355,7 +1373,7 @@ uint64_t amdgpu_ttm_tt_pde_flags(struct ttm_tt *ttm,
> struct ttm_resource *mem)
>
> if (mem && (mem->mem_type == TTM_PL_TT ||
> mem->mem_type == AMDGPU_PL_DOORBELL ||
> - mem->mem_type == AMDGPU_PL_PREEMPT)) {
> + mem->mem_type == AMDGPU_PL_PREEMPT || mem->mem_type ==
> AMDGPU_PL_MMIO_REMAP)) {
> flags |= AMDGPU_PTE_SYSTEM;
>
> if (ttm->caching == ttm_cached)
> --
> 2.34.1
>
