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[142.162.113.180]) by smtp.gmail.com with ESMTPSA id o201sm1395090qka.17.2019.11.21.05.44.38 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 21 Nov 2019 05:44:38 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iXmlC-0002Gd-Fz; Thu, 21 Nov 2019 09:44:38 -0400 Date: Thu, 21 Nov 2019 09:44:38 -0400 From: Jason Gunthorpe To: "Michael S. Tsirkin" Cc: Alex Williamson , Jason Wang , Parav Pandit , Jeff Kirsher , davem@davemloft.net, gregkh@linuxfoundation.org, Dave Ertman , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, nhorman@redhat.com, sassmann@redhat.com, Kiran Patil , Tiwei Bie Subject: Re: [net-next v2 1/1] virtual-bus: Implementation of Virtual Bus Message-ID: <20191121134438.GA7448@ziepe.ca> References: <20191119231023.GN4991@ziepe.ca> <20191119191053-mutt-send-email-mst@kernel.org> <20191120014653.GR4991@ziepe.ca> <134058913.35624136.1574222360435.JavaMail.zimbra@redhat.com> <20191120133835.GC22515@ziepe.ca> <20191120102856.7e01e2e2@x1.home> <20191120181108.GJ22515@ziepe.ca> <20191120150732.2fffa141@x1.home> <20191121030357.GB16914@ziepe.ca> <20191120232320-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191120232320-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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