Re: [RFC] /dev/ioasid uAPI proposal

From: Paolo Bonzini
Date: Wed Jun 09 2021 - 09:24:21 EST

On 09/06/21 14:47, Jason Gunthorpe wrote:
On Wed, Jun 09, 2021 at 02:46:05PM +0200, Paolo Bonzini wrote:
On 09/06/21 13:57, Jason Gunthorpe wrote:
On Wed, Jun 09, 2021 at 02:49:32AM +0000, Tian, Kevin wrote:

Last unclosed open. Jason, you dislike symbol_get in this contract per
earlier comment. As Alex explained, looks it's more about module
dependency which is orthogonal to how this contract is designed. What
is your opinion now?

Generally when you see symbol_get like this it suggests something is
wrong in the layering..

Why shouldn't kvm have a normal module dependency on drivers/iommu?

It allows KVM to load even if there's an "install /bin/false" for vfio
(typically used together with the blacklist directive) in modprobe.conf.
This rationale should apply to iommu as well.

I can vaugely understand this rational for vfio, but not at all for
the platform's iommu driver, sorry.

Sorry, should apply to ioasid, not iommu (assuming that /dev/ioasid support would be modular).