From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x2254mueQN8hABEn5gqO3p5QHSmPuHlhO5U4ReSKQzKu9IqnwbtEL5AoTXpuTIrfjfsgCaO7w ARC-Seal: i=1; a=rsa-sha256; t=1517986822; cv=none; d=google.com; s=arc-20160816; b=mR76vpH1qJC0Isu5Tr4Ppav+cW5zBXS4jzKD196EQAfOmh6wxtnQ3jkJwXmfcXl8rY yvRN3xiy7y3ZLoofEfM9Bbtd2v4rbKouAmmuGdMF0t0XTThBzQwPsiwZYu8rbOuA0Cp+ RQJbSwOQ5KawC6MWxhd4ZPulNz9gsv+FqmTC4XuRfrhFRMmFMkJUmtLcLXZDq1wjAH7d 4oZCiZUmxh/O9SZkdfakPJON6oIOA1SFpkXO8TufBMafA3fE3o/fY9yJsufiLOCko5EO fK11VEHOCzm4nYtBBR+k4XoxNq/tDz/0jQ1QhJfSQb9HgFDbMDSb21mmARGCSk5SMoTj TpHw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:references:in-reply-to:date:subject:cc:to:from :arc-authentication-results; bh=aBdzwPztLsAUnYudQkCKcKQabIA2VY33YdePNa5qEJ0=; b=DxCqQPkXJ9iXeL/Lc5Qc+uPTT79NRbzVglwmuvzHoWBdOyjQAHgK+d+E97xYb9g6wx PY4GEoQ41qYWqAAGzGLic9JW2URLipNySDs7RT/2/Rk8S9SOwxfCTduK9zJ1vvrdA+9Z Ep3MM9qIHVLwc7wFVLPDDlN3jnGQYPWGv2aP0+wY0UE5/h43ESgBXt2QVWnVu6O2ylVo Abr+S/8McXX4xP6boNXdgFE6NQRrG9hy2qceQ9y0Aj9vLMnRd2MabCv3DjkTFY7mL9r5 2mX1p5DEWJBxwrsSNVhiJm1cm+NMZluKtQEAZcsy/ERQVs9KcvIrLEEZ/bQrUrNUf7C5 Nn6g== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of schwidefsky@de.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=schwidefsky@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 schwidefsky@de.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=schwidefsky@de.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com From: Martin Schwidefsky To: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: Heiko Carstens , Christian Borntraeger , Cornelia Huck , David Hildenbrand , Greg Kroah-Hartman , Jon Masters , Marcus Meissner , Jiri Kosina , Dominik Brodowski , Alan Cox , Pavel Machek , David Woodhouse Subject: [PATCH 1/6] s390: scrub registers on kernel entry and KVM exit Date: Wed, 7 Feb 2018 08:00:06 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com> References: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18020707-0016-0000-0000-0000052033DC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18020707-0017-0000-0000-0000285CE859 Message-Id: <1517986811-27819-2-git-send-email-schwidefsky@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-07_01:,, 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=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802070089 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1591724550351408099?= X-GMAIL-MSGID: =?utf-8?q?1591724550351408099?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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. Reviewed-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/entry.S | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 6cd444d..5d87eda 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -248,6 +248,12 @@ ENTRY(sie64a) sie_exit: lg %r14,__SF_EMPTY+8(%r15) # load guest register save area stmg %r0,%r13,0(%r14) # save guest gprs 0-13 + xgr %r0,%r0 # clear guest registers to + xgr %r1,%r1 # prevent speculative use + xgr %r2,%r2 + xgr %r3,%r3 + xgr %r4,%r4 + xgr %r5,%r5 lmg %r6,%r14,__SF_GPRS(%r15) # restore kernel registers lg %r2,__SF_EMPTY+16(%r15) # return exit reason code br %r14 @@ -282,6 +288,8 @@ ENTRY(system_call) .Lsysc_vtime: UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER stmg %r0,%r7,__PT_R0(%r11) + # clear user controlled register to prevent speculative use + xgr %r0,%r0 mvc __PT_R8(64,%r11),__LC_SAVE_AREA_SYNC mvc __PT_PSW(16,%r11),__LC_SVC_OLD_PSW mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC @@ -561,6 +569,15 @@ ENTRY(pgm_check_handler) 4: lgr %r13,%r11 la %r11,STACK_FRAME_OVERHEAD(%r15) stmg %r0,%r7,__PT_R0(%r11) + # clear user controlled registers to prevent speculative use + xgr %r0,%r0 + xgr %r1,%r1 + xgr %r2,%r2 + xgr %r3,%r3 + xgr %r4,%r4 + xgr %r5,%r5 + xgr %r6,%r6 + xgr %r7,%r7 mvc __PT_R8(64,%r11),__LC_SAVE_AREA_SYNC stmg %r8,%r9,__PT_PSW(%r11) mvc __PT_INT_CODE(4,%r11),__LC_PGM_ILC @@ -626,6 +643,16 @@ ENTRY(io_int_handler) lmg %r8,%r9,__LC_IO_OLD_PSW SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_ENTER_TIMER stmg %r0,%r7,__PT_R0(%r11) + # clear user controlled registers to prevent speculative use + xgr %r0,%r0 + xgr %r1,%r1 + xgr %r2,%r2 + xgr %r3,%r3 + xgr %r4,%r4 + xgr %r5,%r5 + xgr %r6,%r6 + xgr %r7,%r7 + xgr %r10,%r10 mvc __PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC stmg %r8,%r9,__PT_PSW(%r11) mvc __PT_INT_CODE(12,%r11),__LC_SUBCHANNEL_ID @@ -839,6 +866,16 @@ ENTRY(ext_int_handler) lmg %r8,%r9,__LC_EXT_OLD_PSW SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_ENTER_TIMER stmg %r0,%r7,__PT_R0(%r11) + # clear user controlled registers to prevent speculative use + xgr %r0,%r0 + xgr %r1,%r1 + xgr %r2,%r2 + xgr %r3,%r3 + xgr %r4,%r4 + xgr %r5,%r5 + xgr %r6,%r6 + xgr %r7,%r7 + xgr %r10,%r10 mvc __PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC stmg %r8,%r9,__PT_PSW(%r11) lghi %r1,__LC_EXT_PARAMS2 @@ -1046,6 +1083,16 @@ ENTRY(mcck_int_handler) .Lmcck_skip: lghi %r14,__LC_GPREGS_SAVE_AREA+64 stmg %r0,%r7,__PT_R0(%r11) + # clear user controlled registers to prevent speculative use + xgr %r0,%r0 + xgr %r1,%r1 + xgr %r2,%r2 + xgr %r3,%r3 + xgr %r4,%r4 + xgr %r5,%r5 + xgr %r6,%r6 + xgr %r7,%r7 + xgr %r10,%r10 mvc __PT_R8(64,%r11),0(%r14) stmg %r8,%r9,__PT_PSW(%r11) xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11) -- 2.7.4