From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E52526ED41; Thu, 6 Aug 2026 14:20:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786026046; cv=none; b=EzZUDXPWJWL0XXIGvBHK5LjBctCK/be9fLclk2pBujAqUQ2QOqIszYv5jZakiqjSRhDxkgMltNejq6r2IeOsZeH5LYrh2dgoNXZVlTtgMOuwN9UnDz/jWPXVVc6grW5mCs4hOqQyugK1Pd2iiuDEQd9s2H5Z9PMS6HWWi4dmKiY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786026046; c=relaxed/simple; bh=cwo+XfXTMp8Vp8goaC/CvZC/oCawJ+bK/4EMDmEh0ds=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XmOJHnq5D82bslKW45NHo6AE/muaK3HBwivI5C247jVEc8Le7hTJRXzshtFmbRuxLQUuLCvoBbnZS2vPvC2IQpMEOwxvXg16cXu11BhAju6Qb7A7vj5BTezQNTVhnCrvtRS/oI4UZMynHMMRzMf66p7/kq982/Rrqold3dsWd7s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=IU7s8ppG; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="IU7s8ppG" Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 676Do7Y31092931; Thu, 6 Aug 2026 14:20:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=pp1; bh=+3hLOyyIYllLKq3fwT9UK4DRilTLms 9J3bUd5JwUABw=; b=IU7s8ppG6eAh/MR/5ZyYmVoIMCXrs66DUdBip+S9J2ztpW sTAz3OSw5UvglgvCwhkaeQ5mR/UlJMeTsj8PuRmXS2+EaGV+OKk/tkXKvcyrw3nL d0W2yeMit63O/xyLHDxbpN3SeDNrodqylZzwPQv/+kRwg7dhMgw/k2IdT3sLjm9c drxSkhfAnCz35I7kgaU6NucU9NRRed1VsBTn7QB7WpGWL8ajkozx/dgEbw3K+oWj nsfsarwjWYGuTFP/6EWbH5VxMsnoyzCOyag0zUXEaeEweikhYx7GRRwySmYr0uKb O2mxoKzjJkGN5mbG3pDASyjl0oPkk8KBJGiH1HCA== Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fs8h58psy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 06 Aug 2026 14:20:43 +0000 (GMT) Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 676EBJNI024568; Thu, 6 Aug 2026 14:20:42 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 4fsu4qun03-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 06 Aug 2026 14:20:42 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 676EKcQ952298120 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 6 Aug 2026 14:20:38 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 71C0820043; Thu, 6 Aug 2026 14:20:38 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 178A920040; Thu, 6 Aug 2026 14:20:38 +0000 (GMT) Received: from osiris (unknown [9.111.55.125]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTPS; Thu, 6 Aug 2026 14:20:38 +0000 (GMT) Date: Thu, 6 Aug 2026 16:20:36 +0200 From: Heiko Carstens To: Christian Borntraeger Cc: Janosch Frank , Claudio Imbrenda , KVM , David Hildenbrand , linux-s390 , Vasily Gorbik , Alexander Gordeev , Sven Schnelle Subject: Re: [PATCH 1/1] KVM: s390: Fix memory corruption by not reinjecting CK machine checks Message-ID: <20260806142036.15764Eaf-hca@linux.ibm.com> References: <20260806125241.210170-1-borntraeger@linux.ibm.com> <20260806125241.210170-2-borntraeger@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260806125241.210170-2-borntraeger@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwODA2MDExMiBTYWx0ZWRfX3xCCU+Tm8iep DxpAoPjJ0+nXIsMK96pVWCySYpmu9xRQx/3IZjtGZFMzPiNJ5XqAcccONb0GtTn470OVDiYY/CK dig5blXA+4lFz+GLLQ8c8/qr2D43zK8= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA2MDExMiBTYWx0ZWRfX9tTZYrr0ATu1 YPzDdjWAe523p+lIYrUUb5j0uS5i60b6RARt8BekxRJ9iPi5UDn1t6iNgSKPdeWG24W1zuJnmHG WYVnnO+hGGOtr+lzJ2ATxqSD4JL0uO9t8/VFDrU1tVDmtnxpCho+dNOnBCAxSzdMNgKqYgDte6A lZhDmIfLvScPCwYrfYRLI/D3cU/f0b+Emtr9YQEhD2uHbTo/LOpd/CnEZmeG4cL8yN0jvEGhLOS v3uh2RkGZ78kvrVz4ouBSnztpw7YMBP4qovlM7t6tF+4FtSGCDNdY2Suj0JXBJoKbY7XJ1Hn0TK 1XzP6ccueSYdJQk0JamW8zSEruT25jRzwEUA6eawi4X7Cnu0McV6PhiOqaO7qnVL8wOZLn2kEBS yDBbQmoKZEmzYoXYqBZnmM4OpTxrl2fIQbg7GsyDmr71i5EFMIJ+X+qZ4YXmKRTObRprcAzYcYV rzaC86hLXlAZpXhYBWA== X-Authority-Analysis: v=2.4 cv=SI1ykuvH c=1 sm=1 tr=0 ts=6a74983b cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=kj9zAlcOel0A:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=WOMeMtZcLbvEFOhP14wA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: w8yY2Ph_y1Ru6d1aVrvE7GDbZj6ULh9K X-Proofpoint-GUID: w8yY2Ph_y1Ru6d1aVrvE7GDbZj6ULh9K X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_06,2026-08-05_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 suspectscore=0 impostorscore=0 spamscore=0 phishscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608060112 On Thu, Aug 06, 2026 at 02:52:41PM +0200, Christian Borntraeger wrote: > Channel-subsystem damage machine checks are for the host channel > subsystem. The guest channel subsystem is emulated in the userspace VMM. > There is no point in forwarding such machine checks into the guest. > > This also simplifies the machine check reinjection and avoids kfree of a > stack variable as reported by sashiko. There might be still machine > checks that have the ck bit set with another bit (like instruction > damage), mask out the CK bit in s390_backup_mcck_info(), like the CP and > ED bits already are. > > Fixes: 4d62fcc0b692 ("KVM: s390: Inject machine check into the guest") > Cc: stable@vger.kernel.org > Signed-off-by: Christian Borntraeger > --- > arch/s390/include/asm/nmi.h | 1 + > arch/s390/kernel/nmi.c | 4 ++-- > arch/s390/kvm/interrupt.c | 24 ++++++++---------------- > 3 files changed, 11 insertions(+), 18 deletions(-) > > diff --git a/arch/s390/include/asm/nmi.h b/arch/s390/include/asm/nmi.h > index 6454c1531854..dd26c20bd231 100644 > --- a/arch/s390/include/asm/nmi.h > +++ b/arch/s390/include/asm/nmi.h > @@ -22,6 +22,7 @@ > #define MCCK_CODE_SYSTEM_DAMAGE BIT(63) > #define MCCK_CODE_EXT_DAMAGE BIT(63 - 5) > #define MCCK_CODE_CP BIT(63 - 9) > +#define MCCK_CODE_CK BIT(63 - 11) > #define MCCK_CODE_STG_ERROR BIT(63 - 16) > #define MCCK_CODE_STG_KEY_ERROR BIT(63 - 18) > #define MCCK_CODE_STG_DEGRAD BIT(63 - 19) > diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c > index e17a59d4d5a4..652b98795243 100644 > --- a/arch/s390/kernel/nmi.c > +++ b/arch/s390/kernel/nmi.c > @@ -345,7 +345,7 @@ static void notrace s390_backup_mcck_info(struct pt_regs *regs) > sie_page = container_of(sie_block, struct sie_page, sie_block); > mcck_backup = &sie_page->mcck_info; > mcck_backup->mcic = get_lowcore()->mcck_interruption_code & > - ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE); > + ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE | MCCK_CODE_CK); > mcck_backup->ext_damage_code = get_lowcore()->external_damage_code; > mcck_backup->failing_storage_address = get_lowcore()->failing_storage_address; > } > @@ -357,7 +357,7 @@ NOKPROBE_SYMBOL(s390_backup_mcck_info); > #define ED_STP_ISLAND 6 /* External damage STP island check */ > #define ED_STP_SYNC 7 /* External damage STP sync check */ > > -#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE) > +#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE | MCCK_CODE_CK) So what you proposed in the cover-letter is to change the above to: mcck_backup->mcic = get_lowcore()->mcck_interruption_code & ~MCCK_CODE_NO_GUEST; Right? Yes, pleae do that! And this can also go via kvm. Acked-by: Heiko Carstens