From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v4 19/21] xen/arm: grant: Add another entry to map MFN 1:1 in dom0 p2m Date: Mon, 28 Apr 2014 15:11:56 +0100 Message-ID: <1398694316.29700.128.camel@kazak.uk.xensource.com> References: <1398172475-27873-1-git-send-email-julien.grall@linaro.org> <1398172475-27873-20-git-send-email-julien.grall@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WemHo-0002qx-Qu for xen-devel@lists.xenproject.org; Mon, 28 Apr 2014 14:12:00 +0000 In-Reply-To: <1398172475-27873-20-git-send-email-julien.grall@linaro.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall Cc: xen-devel@lists.xenproject.org, tim@xen.org, stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org On Tue, 2014-04-22 at 14:14 +0100, Julien Grall wrote: > Grant mapping can be used for DMA request. The dev_bus_addr returned by the > hypercall is the MFN (not the IPA). Currently Linux is using this address (via > swiotlb) to program the DMA. > When the device is protected by IOMMU the request will fail. We have to > add 1:1 mapping in the domain p2m to allow DMA request working. > > This is valid because DOM0 has its memory mapped 1:1. Go on to say: ... and therefore we know that RAM and devices cannot clash (or something). > Signed-off-by: Julien Grall With that: Acked-by: Ian Campbell