From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 3F7A952ED3D for ; Wed, 9 Sep 2026 10:45:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788950734; cv=none; b=IVJ6rq/jfLPTIT2GtCGuV8PAR+kQOyutfZ1qd4HDAaB61alAfndsbw/spXiQ37+Kr4Eahr9bHI8Ct83R12Ikj9GZsACuZ+hZeSGCepLR3h+P0GTB19Oki8dJi9fiXrlxHJcs5A7TTH7dGwhcT1TOkhYwgSLCSApk5YTiyVom0Pk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788950734; c=relaxed/simple; bh=s1W1e8IlmhTs5+Gj/EhgchVYiwaX/GpDjeKOS1QMk74=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=bJbtUlvvrP3FqUu0bEuWyFrfjePD3AqSb8E45t8asZYKAJWxdGnQNnPjF/YH/eC+qzrEFNJ8efACRD/X98JvOWLVwPmJRzT+wkosYgr9ksArfomv+R+Mn4R2zapl0y5lMx+Jz515UroidADVp+FGCrRrZEDOHxhT6gAXpsAkaws= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0v+9QPum; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0v+9QPum" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E4951F00A3A; Wed, 9 Sep 2026 10:45:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788950733; bh=OgLSLh8ocMBS2/GCJS9G3pzmprSuC9gbGaGpyeNK35M=; h=Subject:To:Cc:From:Date; b=0v+9QPumJ3PCL+h2I/KOGPYSqJlSZzz4dH7nmMpBC49Q41cpNUR4i/Rcf2xm2bjQw B9xd3YPhGLu9T9kERTywo/uoELPJZaa/p4WXuRKroU+ob1Z01BmJbQRDZ66/7MgU3v 7jWMzPKFnrBfTKjvA+tqvMm8W7XnRGglBmtrNgY4= Subject: FAILED: patch "[PATCH] KVM: s390: Fix memory corruption by not reinjecting CK" failed to apply to 6.6-stable tree To: borntraeger@linux.ibm.com,hca@linux.ibm.com,imbrenda@linux.ibm.com Cc: From: Date: Wed, 09 Sep 2026 12:35:45 +0200 Message-ID: <2026090944-culprit-impeding-88fc@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 546dde823a36d7283dcf46127c2f3d093443860f # git commit -s git send-email --to '' --in-reply-to '2026090944-culprit-impeding-88fc@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 546dde823a36d7283dcf46127c2f3d093443860f Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 6 Aug 2026 16:58:35 +0200 Subject: [PATCH] KVM: s390: Fix memory corruption by not reinjecting CK machine checks 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 Acked-by: Heiko Carstens Acked-by: Claudio Imbrenda Signed-off-by: Claudio Imbrenda Message-ID: <20260806145835.31818-1-borntraeger@linux.ibm.com> diff --git a/arch/s390/include/asm/nmi.h b/arch/s390/include/asm/nmi.h index 6454c1531854..7919b2b9ac9c 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) @@ -33,6 +34,8 @@ #define MCCK_CODE_FC_VALID BIT(63 - 43) #define MCCK_CODE_CPU_TIMER_VALID BIT(63 - 46) +#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE | MCCK_CODE_CK) + #ifndef __ASSEMBLER__ union mci { diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index e17a59d4d5a4..17297a8b63d9 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -344,8 +344,7 @@ 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_backup->mcic = get_lowcore()->mcck_interruption_code & ~MCCK_CODE_NO_GUEST; mcck_backup->ext_damage_code = get_lowcore()->external_damage_code; mcck_backup->failing_storage_address = get_lowcore()->failing_storage_address; } @@ -357,8 +356,6 @@ 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) - /* * machine check handler. */ diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 009d6a845d59..0d9fbe75dc66 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -3108,9 +3108,7 @@ static int set_adapter_int(struct kvm_kernel_irq_routing_entry *e, void kvm_s390_reinject_machine_check(struct kvm_vcpu *vcpu, struct mcck_volatile_info *mcck_info) { - struct kvm_s390_interrupt_info inti; struct kvm_s390_irq irq = {}; - struct kvm_s390_mchk_info *mchk; union mci mci; __u64 cr14 = 0; /* upper bits are not used */ int rc; @@ -3129,20 +3127,14 @@ void kvm_s390_reinject_machine_check(struct kvm_vcpu *vcpu, if (mci.w) cr14 |= CR14_WARNING_SUBMASK; - mchk = mci.ck ? &inti.mchk : &irq.u.mchk; - mchk->cr14 = cr14; - mchk->mcic = mcck_info->mcic; - mchk->ext_damage_code = mcck_info->ext_damage_code; - mchk->failing_storage_address = mcck_info->failing_storage_address; - if (mci.ck) { - /* Inject the floating machine check */ - inti.type = KVM_S390_MCHK; - rc = __inject_vm(vcpu->kvm, &inti); - } else { - /* Inject the machine check to specified vcpu */ - irq.type = KVM_S390_MCHK; - rc = kvm_s390_inject_vcpu(vcpu, &irq); - } + irq.u.mchk.cr14 = cr14; + irq.u.mchk.mcic = mcck_info->mcic; + irq.u.mchk.ext_damage_code = mcck_info->ext_damage_code; + irq.u.mchk.failing_storage_address = mcck_info->failing_storage_address; + + /* Inject the machine check to specified vcpu */ + irq.type = KVM_S390_MCHK; + rc = kvm_s390_inject_vcpu(vcpu, &irq); WARN_ON_ONCE(rc); }