Re: [PATCH V5 12/12] net: netvsc: Add Isolation VM support for netvsc driver

Christoph Hellwig
2021-09-28T05:39:23Z

On Mon, Sep 27, 2021 at 10:26:43PM +0800, Tianyu Lan wrote:
> Hi Christoph:
> Gentile ping. The swiotlb and shared memory mapping changes in this
> patchset needs your reivew. Could you have a look?

I'm a little too busy for a review of such a huge patchset right now.
That being said here are my comments from a very quick review:

- the bare memremap usage in swiotlb looks strange and I'd
definitively expect a well documented wrapper.
- given that we can now hand out swiotlb memory for coherent mappings
we need to carefully audit what happens when this memremaped
memory gets mmaped or used through dma_get_sgtable
- the netscv changes I'm not happy with at all. A large part of it
is that the driver already has a bad structure, but this series
is making it significantly worse. We'll need to find a way
to use the proper dma mapping abstractions here. One option
if you want to stick to the double vmapped buffer would be something
like using dma_alloc_noncontigous plus a variant of
dma_vmap_noncontiguous that takes the shared_gpa_boundary into
account.