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

From: Tianyu Lan
Date: Tue Sep 28 2021 - 05:23:52 EST

On 9/28/2021 1:39 PM, Christoph Hellwig wrote:
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:
Hi Christoph:
Thanks for your comments. Most patches in the series are Hyper-V
change. I will split patchset and make it easy to review.

- the bare memremap usage in swiotlb looks strange and I'd
definitively expect a well documented wrapper.

OK. Should the wrapper in the DMA code? How about dma_map_decrypted() introduced in the V4?

- 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

OK. I check that.

- 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

OK. I will do that.