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Violators will be prosecuted; Fri, 19 Jan 2018 03:27:31 -0500 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w0J8RTA553674178; Fri, 19 Jan 2018 08:27:29 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7BFCFAE056; Fri, 19 Jan 2018 03:28:43 -0500 (EST) Received: from [9.125.65.177] (unknown [9.125.65.177]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTPS id C842BAE052; Fri, 19 Jan 2018 03:28:39 -0500 (EST) Subject: Re: [PATCH 6/6] s390: scrub registers on kernel entry and KVM exit To: Christian Borntraeger , Martin Schwidefsky , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org Cc: Heiko Carstens , Paolo Bonzini , Cornelia Huck , Greg Kroah-Hartman , Jon Masters , Marcus Meissner , Jiri Kosina References: <1516182519-10623-1-git-send-email-schwidefsky@de.ibm.com> <1516182519-10623-7-git-send-email-schwidefsky@de.ibm.com> From: QingFeng Hao Date: Fri, 19 Jan 2018 16:27:08 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 18011908-0036-0000-0000-000002AF1D1D X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008405; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000247; SDB=6.00977191; UDB=6.00495433; IPR=6.00757113; BA=6.00005782; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00019125; XFM=3.00000015; UTC=2018-01-19 08:27:34 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011908-0037-0000-0000-0000430B3D03 Message-Id: <34660999-606f-0cab-6630-4116ad833c77@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-01-19_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1801190108 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ?? 2018/1/19 15:57, Christian Borntraeger д??: > > On 01/19/2018 07:29 AM, QingFeng Hao wrote: >> >> ?? 2018/1/17 17:48, Martin Schwidefsky д??: >>> Clear all user space registers on entry to the kernel and all KVM guest >>> registers on KVM guest exit if the register does not contain either a >>> parameter or a result value. >> I am not sure if I understand this but it will be safer? > It ist similar to commit 0cb5b30698fd ("kvm: vmx: Scrub hardware GPRs at VM-exit"). > The idea is to minimize potential payload channels. Got it! thanks for your explanation! > >> And can we abstract the operations to be a macro like CLEAR_REG_7? > No, please. > xgr %r7,%r7 > is absolutely clear what it does, a MACRO often is not. nod, this makes sense! -- Regards QingFeng Hao