On Thu, Sep 21, 2023 at 03:39:26PM -0300, Jason Gunthorpe wrote: > On Thu, Sep 21, 2023 at 12:53:04PM -0400, Michael S. Tsirkin wrote: > > > vdpa is not vfio, I don't know how you can suggest vdpa is a > > > replacement for a vfio driver. They are completely different > > > things. > > > Each side has its own strengths, and vfio especially is accelerating > > > in its capability in way that vpda is not. eg if an iommufd conversion > > > had been done by now for vdpa I might be more sympathetic. > > > > Yea, I agree iommufd is a big problem with vdpa right now. Cindy was > > sick and I didn't know and kept assuming she's working on this. I don't > > think it's a huge amount of work though. I'll take a look. > > Is there anything else though? Do tell. > > Confidential compute will never work with VDPA's approach. I don't see how what this patchset is doing is different wrt to Confidential compute - you trap IO accesses and emulate. Care to elaborate? > > There are a bunch of things that I think are important for virtio > > that are completely out of scope for vfio, such as migrating > > cross-vendor. > > VFIO supports migration, if you want to have cross-vendor migration > then make a standard that describes the VFIO migration data format for > virtio devices. This has nothing to do with data formats - you need two devices to behave identically. Which is what VDPA is about really. > > What is the huge amount of work am I asking to do? > > You are asking us to invest in the complexity of VDPA through out > (keep it working, keep it secure, invest time in deploying and > debugging in the field) > > When it doesn't provide *ANY* value to the solution. There's no "the solution" - this sounds like a vendor only caring about solutions that involve that vendor's hardware exclusively, a little. > The starting point is a completely working vfio PCI function and the > end goal is to put that function into a VM. That is VFIO, not VDPA. > > VPDA is fine for what it does, but it is not a reasonable replacement > for VFIO. > > Jason VDPA basically should be a kind of "VFIO for virtio". -- MST
