From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC 0/3] virtio-iommu: a paravirtualized IOMMU Date: Sat, 8 Apr 2017 00:19:22 +0300 Message-ID: <20170407211922.GA23772@redhat.com> References: <20170407191747.26618-1-jean-philippe.brucker@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: iommu@lists.linux-foundation.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, cdall@linaro.org, will.deacon@arm.com, robin.murphy@arm.com, lorenzo.pieralisi@arm.com, joro@8bytes.org, jasowang@redhat.com, alex.williamson@redhat.com, marc.zyngier@arm.com To: Jean-Philippe Brucker Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Content-Disposition: inline In-Reply-To: <20170407191747.26618-1-jean-philippe.brucker@arm.com> List-Id: kvm.vger.kernel.org On Fri, Apr 07, 2017 at 08:17:44PM +0100, Jean-Philippe Brucker wrote: > There are a number of advantages in a paravirtualized IOMMU over a full > emulation. It is portable and could be reused on different architectures. > It is easier to implement than a full emulation, with less state tracking. > It might be more efficient in some cases, with less context switches to > the host and the possibility of in-kernel emulation. Thanks, this is very interesting. I am read to read it all, but I really would like you to expand some more on the motivation for this work. Productising this would be quite a bit of work. Spending just 6 lines on motivation seems somewhat disproportionate. In particular, do you have any specific efficiency measurements or estimates that you can share? -- MST