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Message-ID: <20191121134438.GA7448@ziepe.ca>
Date: Thu, 21 Nov 2019 09:44:38 -0400
From: Jason Gunthorpe <jgg@...pe.ca>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Alex Williamson <alex.williamson@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Parav Pandit <parav@...lanox.com>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
davem@...emloft.net, gregkh@...uxfoundation.org,
Dave Ertman <david.m.ertman@...el.com>, netdev@...r.kernel.org,
linux-rdma@...r.kernel.org, nhorman@...hat.com,
sassmann@...hat.com, Kiran Patil <kiran.patil@...el.com>,
Tiwei Bie <tiwei.bie@...el.com>
Subject: Re: [net-next v2 1/1] virtual-bus: Implementation of Virtual Bus
On Wed, Nov 20, 2019 at 11:24:03PM -0500, Michael S. Tsirkin wrote:
> On Wed, Nov 20, 2019 at 11:03:57PM -0400, Jason Gunthorpe wrote:
> > Frankly, when I look at what this virtio stuff is doing I see RDMA:
> > - Both have a secure BAR pages for mmaping to userspace (or VM)
> > - Both are prevented from interacting with the device at a register
> > level and must call to the kernel - ie creating resources is a
> > kernel call - for security.
> > - Both create command request/response rings in userspace controlled
> > memory and have HW DMA to read requests and DMA to generate responses
> > - Both allow the work on the rings to DMA outside the ring to
> > addresses controlled by userspace.
> > - Both have to support a mixture of HW that uses on-device security
> > or IOMMU based security.
>
> The main difference is userspace/drivers need to be portable with
> virtio.
rdma also has a stable/portable user space library API that is
portable to multiple operating systems.
What you don't like is that RDMA userspace has driver-specific
code. Ie the kernel interface is not fully hardware independent.
Jason
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