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

[Marcel Apfelbaum <marcel@redhat.com>]

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 <marcel@redhat.com>
>> Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
>> ---
>>   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

>> +
>> +
[...]