From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v4 23/33] xen/passthrough: iommu_deassign_device_dt: By default reassign device to nobody Date: Tue, 31 Mar 2015 12:16:49 +0100 Message-ID: <1427800609.2115.78.camel@citrix.com> References: <1426793399-6283-1-git-send-email-julien.grall@linaro.org> <1426793399-6283-24-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.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YcuAA-0000Fo-9p for xen-devel@lists.xenproject.org; Tue, 31 Mar 2015 11:16:54 +0000 In-Reply-To: <1426793399-6283-24-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 Thu, 2015-03-19 at 19:29 +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. > > Signed-off-by: Julien Grall > Acked-by: Stefano Stabellini Acked-by: Ian Campbell