[PATCH v3 01/11] PCI/P2PDMA: Support peer-to-peer memory

[Logan Gunthorpe]

On 13/03/18 01:53 PM, Sinan Kaya wrote:
> I agree disabling globally would be bad. Somebody can always say I have
> ten switches on my system. I want to do peer-to-peer on one switch only. Now,
> this change weakened security for the other switches that I had no intention
> with doing P2P.
> 
> Isn't this a problem?

Well, if it's a problem for someone they'll have to solve it. We're
targeting JBOFs that have no use for ACS / IOMMU groups at all.

> Can we specify the BDF of the downstream device we want P2P with during boot via
> kernel command line?

That's a painful configuration burden. And then things might stop
working if you change your topology at all and now have to change boot
parameters.

Logan