From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: Re: [Qemu-devel] [PATCH RFC] hw/pvrdma: Proposal of a new pvrdma device Date: Mon, 3 Apr 2017 09:27:30 +0300 Message-ID: <20170403062730.GP20443@mtr-leonro.local> References: <1490872341-9959-1-git-send-email-marcel@redhat.com> <20170330141314.GM20443@mtr-leonro.local> <5e952524-7c2d-b4da-4bd7-6437830a40d8@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="i7KxW38SoMauyveo" Return-path: Content-Disposition: inline In-Reply-To: <5e952524-7c2d-b4da-4bd7-6437830a40d8-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Ledford Cc: Marcel Apfelbaum , qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yuval.shaia-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org List-Id: linux-rdma@vger.kernel.org --i7KxW38SoMauyveo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Mar 30, 2017 at 03:28:21PM -0500, Doug Ledford wrote: > On 3/30/17 9:13 AM, Leon Romanovsky wrote: > > On Thu, Mar 30, 2017 at 02:12:21PM +0300, Marcel Apfelbaum wrote: > > > From: Yuval Shaia > > > > > > Hi, > > > > > > General description > > > =================== > > > This is a very early RFC of a new RoCE emulated device > > > that enables guests to use the RDMA stack without having > > > a real hardware in the host. > > > > > > The current implementation supports only VM to VM communication > > > on the same host. > > > Down the road we plan to make possible to be able to support > > > inter-machine communication by utilizing physical RoCE devices > > > or Soft RoCE. > > > > > > The goals are: > > > - Reach fast and secure loos-less Inter-VM data exchange. > > > - Support remote VMs or bare metal machines. > > > - Allow VMs migration. > > > - Do not require to pin all VM memory. > > > > > > > > > Objective > > > ========= > > > Have a QEMU implementation of the PVRDMA device. We aim to do so without > > > any change in the PVRDMA guest driver which is already merged into the > > > upstream kernel. > > > > > > > > > RFC status > > > =========== > > > The project is in early development stages and supports > > > only basic send/receive operations. > > > > > > We present it so we can get feedbacks on design, > > > feature demands and to receive comments from the > > > community pointing us to the "right" direction. > > > > If to judge by the feedback which you got from RDMA community > > for kernel proposal [1], this community failed to understand: > > 1. Why do you need new module? > > In this case, this is a qemu module to allow qemu to provide a virt rdma > device to guests that is compatible with the device provided by VMWare's ESX > product. Right now, the vmware_pvrdma driver works only when the guest is > running on a VMWare ESX server product, this would change that. Marcel > mentioned that they are currently making it compatible because that's the > easiest/quickest thing to do, but in the future they might extend beyond > what VMWare's virt rdma driver provides/uses and might then need to either > modify it to work with their extensions or fork and create their own virt > client driver. Doug, As I mentioned during OFA, I just responded to the latest email, but targeted my questions for their module. Sorry for not being clear about it. > > > 2. Why existing solutions are not enough and can't be extended? > > This patch is against the qemu source code, not the kernel. There is no > other solution in the qemu source code, so there is no existing solution to > extend. > > > 3. Why RXE (SoftRoCE) can't be extended to perform this inter-VM > > communication via virtual NIC? > > Eventually they want this to work on real hardware, and to be more or less > transparent to the guest. They will need to make it independent of the > kernel hardware/driver in use. That means their own virt driver, then the > virt driver will eventually hook into whatever hardware is present on the > system, or failing that, fall back to soft RoCE or soft iWARP if that ever > makes it in the kernel. > > > > > > Can you please help us to fill this knowledge gap? > > > > [1] http://marc.info/?l=linux-rdma&m=149063626907175&w=2 > --i7KxW38SoMauyveo Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkhr/r4Op1/04yqaB5GN7iDZyWKcFAljh61IACgkQ5GN7iDZy WKfwtg//RAhltqcBrIa5Xnef3dc9WUrUVzpqCf2r7MIf8OBCdKyea+eLwz0RbLiF nzv1ZJPZfDvQFVCWbNSOVzjACp2rEtx79g732Xp+4eL/9wzBZmBI0HuIvH6H/6ci uApwILW/FTAGJL+jXX953Oml2yxEvGzvp7pq36NKj8utsjgJcDZMjp6/IhE+6NzP BVJo+W3l3MmhFO9kCBnWtZnP6UbxDkny+EVXwBp3PFg1Zdla69FpprhlG38Nojbz wZsWs+aoZrWrRhuXQECeCCKvf/mPmymeUEkdgkXHdarc2iDKtPL8VXtaTK7q4xe2 xh37c1rygN0evaIGpycr7AdVUDEfN/U2ZYPyCLq9WCABZz9A+IctkD4R2IPXfywn l4mwHIKdqxozjgjzREm4vOLi8/YaRpUKK1xmOVuQX8+sMJs7ccaMhME1vIe7KxDA CvvXNRbSOwj88SqwLTcrvE8x3a741aPNK/1kvS0WxyraUakYq5t8tz6/Dky95qXj C3BjFuICOnyy1DKMfvFiyRutybymWJDHCy3WvSsNpfdx22WdUvU1fRmInCaesdyB Ee6dM5wobtdEhhKLWiMlreQef23qj2ThIEslE9NtII6R8vrnmk0WA+8hY/MZFHgZ 9ZqvhVXhfp/IJ+SOc7bh75SJ6wetBNtPHMxKdSaSiO9CWSBlEHM= =kLxZ -----END PGP SIGNATURE----- --i7KxW38SoMauyveo-- -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html