Support accelerated MSM for halo2curves/grumpkin

[huitseeker]

The pasta cycle imports a GPU-accelerated MSM through the pasta-msm crate.
This crate is backed by the Sppark library, which is generic in the curve parameters it operates with.

With another shim (similar to pasta-msm, but adapted to the parameters of the grumpkin cycle), we could have GPU acceleration of the MSM on the Grumpkin / BN254 cycle.

[huitseeker]

/cc @CPerezz @leonardoalt

[srinathsetty]

Hi @huitseeker, is it feasible to make pasta-msm support a collection of curves (including BN254/Grumpkin)? It would be better than having two crates one for pasta curves and another for bn254/grumpkin.

[CPerezz]

We can explore trying integrating the GPU acceleration in halo2-curves if we can somehow make it use the generalizations of the pasta-msm crate. But not sure we have the bandwidth. So would be nice to know if it's even feasible (architecturally-wise) to end up with something that makes sense and is manteinable.

Happy to upstream any speedups under an experimental feature for sure!

[srinathsetty]

@huitseeker should this issue be filed in halo2curves repo rather than here? It seems there is not much to be done in the Nova repository to address this issue.

[CPerezz]

Ohh no @srinathsetty .

We are planning to integrate the ZAL API into halo2 and halo2curves. See: privacy-scaling-explorations/halo2#277

This means that you will have access to GPU-accelerated primitives here. Inherited from halo2curves.
Assuming this was what @huitseeker meant.

[srinathsetty]

Fantastic! Looking forward to it!