Am 2021-05-05 um 1:56 p.m. schrieb Philip Yang:
> After svm range prefetch and migrate to GPU, if GPU has no access or
> access in place attribute, add GPU to range access_bitmap to be able to
> update GPU page table.
I don't think we should change the bitmap_access, because this is
persistent and can be queried by user mode. Changing this would not be
expected by the application. I think instead we should either pass the
prefetch location to the gpuidx parameter of validate_and_map (we should
only do that is xnack is enabled), or change the logic in
validate_and_map to add the prefetch location to the bitmap.
I think to make this reliable we'll need to add more sanity checks to
prefetch to make sure the prefetch location is compatible with all GPUs
that have access_in_place. Otherwise we have to reject the prefetch.
Regards,
Felix
>
> Signed-off-by: Philip Yang <philip.y...@amd.com>
> ---
> drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index d9111fea724b..3b640772d9c5 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -2869,6 +2869,17 @@ svm_range_set_attr(struct kfd_process *p, uint64_t
> start, uint64_t size,
> continue;
> }
>
> + if (migrated && prange->prefetch_loc) {
> + int gpuidx;
> +
> + gpuidx = kfd_process_gpuidx_from_gpuid(p,
> + prange->prefetch_loc);
> + if (gpuidx >= 0 &&
> + !test_bit(gpuidx, prange->bitmap_access) &&
> + !test_bit(gpuidx, prange->bitmap_aip))
> + bitmap_set(prange->bitmap_access, gpuidx, 1);
> + }
> +
> r = svm_range_validate_and_map(mm, prange, MAX_GPU_INSTANCE,
> true, true);
> if (r)
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