From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v4 1/3] iommu: introduce domain attribute for nesting IOMMUs Date: Thu, 25 Sep 2014 16:32:33 +0200 Message-ID: <20140925143233.GB8306@8bytes.org> References: <1411550485-32483-1-git-send-email-will.deacon@arm.com> <1411550485-32483-2-git-send-email-will.deacon@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1411550485-32483-2-git-send-email-will.deacon-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Will Deacon Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Wed, Sep 24, 2014 at 10:21:23AM +0100, Will Deacon wrote: > Some IOMMUs, such as the ARM SMMU, support two stages of translation. > The idea behind such a scheme is to allow a guest operating system to > use the IOMMU for DMA mappings in the first stage of translation, with > the hypervisor then installing mappings in the second stage to provide > isolation of the DMA to the physical range assigned to that virtual > machine. > > In order to allow IOMMU domains to be used for second-stage translation, > this patch adds a new iommu_attr (IOMMU_ATTR_NESTING) for setting > second-stage domains prior to device attach. The attribute can also be > queried to see if a domain is actually making use of nesting. > > Cc: Joerg Roedel > Cc: Alex Williamson > Signed-off-by: Will Deacon Acked-by: Joerg Roedel