From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: ACJfBos/qtE6hRTP+vouC/CmU9veLeNpenbEqOKAKA/s0Nkf7jtb+NT5GAWHhH3LMhuqxqGpltiT ARC-Seal: i=1; a=rsa-sha256; t=1516348680; cv=none; d=google.com; s=arc-20160816; b=j9Pu1o9+YKsibMC06brbTNo3oJPg8dg6GsktwROS/ogXyg+CyYLXPn/dc5Z9cZieev vof4lemz8njmArORif5GVpW1/HD4oxsmYbf5d7Y8gdkjAm5oCnyhJwdTIDdu4+IfY0QB yRAFUOavJi197E9o3jc+Zc8iX0569KXxLdnhbAURLQAvXT8tMq4yVPE8J4b0bp+UV/K9 wGx1/yR0+/CzIEteEPtK22Z3NedUD8MD1tMM7jwaDjEAQiu63aFNI6iv7o1lNrrxtNDv tfz4u/BwynvBNzrgqILoRNA+srU7Is6uiosSkXyNTeA3k7a47Y2cXk5e5nNMraGtKPHv DSoQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:content-transfer-encoding:content-language:in-reply-to :mime-version:user-agent:date:from:references:cc:to:subject :arc-authentication-results; bh=rtPD8ASgVnBEDr3j45WK0Wtt7LDc8v/F8bGyqbqwsKA=; b=dSo1N/IRdxGwLhb/8QP5G649QaG1IESSQnCVrBXdY9uZkY+Bbx4JjozQmqNBAS7P/v OHVgyS5J1et8MNbiOPoZYAUi3CiILO8MvDAaiBANDp9aDkqk+nfUezYOY/e0KD+hYMM5 twt2ruKZejWFmHVF831ltT/KbStIh4B/8BwykVi8818VY0IQJ0XDUPH4Pxunie5Du0Rt 8hpUJQ88aLTymyfjkiutZNDXgyhOVrV5RiEAg/6X8znBlUgU9mnKsiCDai7dwx9nKd4K +Ez7mcFuV2xYLGqZir0rxUkXq9U2ioYmyGfK9zheg1glMidagU8DDP4fftUEP+61GLUS hRHg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of borntraeger@de.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=borntraeger@de.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of borntraeger@de.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=borntraeger@de.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com Subject: Re: [PATCH 6/6] s390: scrub registers on kernel entry and KVM exit To: QingFeng Hao , 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: Christian Borntraeger Date: Fri, 19 Jan 2018 08:57:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=gbk Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 18011907-0040-0000-0000-000004067E60 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011907-0041-0000-0000-00002609F5E0 Message-Id: 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-1801190100 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1589832618248203925?= X-GMAIL-MSGID: =?utf-8?q?1590006834622622289?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 01/19/2018 07:29 AM, QingFeng Hao wrote: > > > ÔÚ 2018/1/17 17:48, Martin Schwidefsky дµÀ: >> 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. > 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.