From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v3 18/24] xen/passthrough: iommu_deassign_device_dt: By default reassign device to nobody Date: Mon, 23 Feb 2015 10:10:45 +0000 Message-ID: <54EAFCA5.2050905@linaro.org> References: <1421159133-31526-1-git-send-email-julien.grall@linaro.org> <1421159133-31526-19-git-send-email-julien.grall@linaro.org> <1424451889.30924.363.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YPpyT-0007Ao-HO for xen-devel@lists.xenproject.org; Mon, 23 Feb 2015 10:10:49 +0000 Received: by wesw62 with SMTP id w62so16883215wes.9 for ; Mon, 23 Feb 2015 02:10:48 -0800 (PST) In-Reply-To: <1424451889.30924.363.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: xen-devel@lists.xenproject.org, tim@xen.org, Jan Beulich , stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org On 20/02/2015 17:04, Ian Campbell wrote: > On Tue, 2015-01-13 at 14:25 +0000, Julien Grall wrote: >> Currently, when the device is deassigned from a domain, we directly reassign >> to DOM0. >> >> As the device may not have been correctly reset, this may lead to corruption or >> expose some part of DOM0 memory. Also, we may have no way to reset some >> platform devices. >> >> If Xen reassigns the device to "nobody", it may receive some global/context >> fault because the transaction has failed (indeed the context has been >> marked invalid). Unfortunately there is no simple way to quiesce a buggy >> hardware. I think we could live with that for a first version of platform >> device passthrough. >> >> DOM0 will have to issue an hypercall to assign the device to itself if it >> wants to use it. > > Does this behaviour differ from x86? If so then it is worth calling that > out explicitly (even if not, good to know I think!) What do you mean by "calling that out explicitly"? Regards, -- Julien Grall