On Tue, Jan 21, 2020 at 02:07:59PM +0000, Jason Gunthorpe wrote:

On Mon, Jan 20, 2020 at 04:25:23PM -0500, Michael S. Tsirkin wrote:

quoted

On Mon, Jan 20, 2020 at 08:51:43PM +0000, Shahaf Shuler wrote:

quoted

Monday, January 20, 2020 7:50 PM, Jason Gunthorpe:

quoted

Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus

On Mon, Jan 20, 2020 at 04:43:53PM +0800, Jason Wang wrote:

quoted

This is similar to the design of platform IOMMU part of vhost-vdpa. We
decide to send diffs to platform IOMMU there. If it's ok to do that in
driver, we can replace set_map with incremental API like map()/unmap().

Then driver need to maintain rbtree itself.

I think we really need to see two modes, one where there is a fixed
translation without dynamic vIOMMU driven changes and one that supports
vIOMMU.

There are different optimization goals in the drivers for these two
configurations.

+1.
It will be best to have one API for static config (i.e. mapping can be
set only before virtio device gets active), and one API for dynamic
changes that can be set after the virtio device is active. 

Frankly I don't see when we'd use the static one.
Memory hotplug is enabled for most guests...

If someone wants to run a full performance application, like dpdk,
then they may wish to trade memory hotplug in that VM for more
performance.

Right. But let let's get basic functionality working first.

Perhaps Shahaf can quantify the performance delta?

Jason