Re: [Qemu-devel] [PATCH V2 3/5] docs: add pvrdma device documentation

[Marcel Apfelbaum]

On 19/12/2017 19:47, Michael S. Tsirkin wrote:
> On Sun, Dec 17, 2017 at 02:54:55PM +0200, Marcel Apfelbaum wrote:
> > Signed-off-by: Marcel Apfelbaum <address@hidden>
> > Signed-off-by: Yuval Shaia <address@hidden>
> > ---
> >   docs/pvrdma.txt | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 145 insertions(+)
> >   create mode 100644 docs/pvrdma.txt
> >
> > diff --git a/docs/pvrdma.txt b/docs/pvrdma.txt
> > new file mode 100644
> > index 0000000000..74c5cf2495
> > --- /dev/null
> > +++ b/docs/pvrdma.txt
> > @@ -0,0 +1,145 @@
> > +Paravirtualized RDMA Device (PVRDMA)
> > +====================================
> > +

[...]

> > +
> > +4. Implementation details
> > +=========================
> > +The device acts like a proxy between the Guest Driver and the host
> > +ibdevice interface.
> > +On configuration path:
> > + - For every hardware resource request (PD/QP/CQ/...) the pvrdma will request
> > +   a resource from the backend interface, maintaining a 1-1 mapping
> > +   between the guest and host.
> > +On data path:
> > + - Every post_send/receive received from the guest will be converted into
> > +   a post_send/receive for the backend. The buffers data will not be touched
> > +   or copied resulting in near bare-metal performance for large enough buffers.
> > + - Completions from the backend interface will result in completions for
> > +   the pvrdma device.

Hi Michael,

> Where's the host/guest interface documented?

It is the VMware PVRDMA spec, I am not sure is publicly available,
we kind of reverse-engineered it.
We will add some info from the linked presentation on the PCI BARs
and how are they used.

Thanks,
Marcel

> > +
> > +
[...]