Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted

Thiago Jung Bauermann
2019-02-04T18:16:10Z

Christoph Hellwig <hch@lst.de> writes:

> On Tue, Jan 29, 2019 at 09:36:08PM -0500, Michael S. Tsirkin wrote:
>> This has been discussed ad nauseum. virtio is all about compatibility.
>> Losing a couple of lines of code isn't worth breaking working setups.
>> People that want "just use DMA API no tricks" now have the option.
>> Setting a flag in a feature bit map is literally a single line
>> of code in the hypervisor. So stop pushing for breaking working
>> legacy setups and just fix it in the right place.
>
> I agree with the legacy aspect. What I am missing is an extremely
> strong wording that says you SHOULD always set this flag for new
> hosts, including an explanation why.

My understanding of ACCESS_PLATFORM is that it means "this device will
behave in all aspects like a regular device attached to this bus". Is
that it? Therefore it should be set because it's the sane thing to do?

--
Thiago Jung Bauermann
IBM Linux Technology Center