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 1240337BE64; Sat, 17 Oct 2026 16:34:42 +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=1792254883; cv=none; b=QbvhesGJUB3A7yOlO7Ww3TAlM/qA8FylTRvQB2c+Q9c9dBeuKDs/JO50X8CNaJ+Lfa39LIcBXgy0nO5wGqsresXRNGTFhICKT3Z5Y8oV0yQUS0Zuv2xfLL0EMzup781qj4Y29EKGC5WwhXXw+MiSLvT+2oEE4C5WpZ+VcfeQQvA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792254883; c=relaxed/simple; bh=q22os2ArYi/nb2rmejj88BN9d0XxXnvy8/88zSR0Zvo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GkQ0FrAGWWUvBYYHUm5Mbcedabp0g+MMVbrmn7oq/UAmsT9vHOcJW4K/tJG5rS0LMCi2BtueALccY4QbtDZCvH89yCf95eSneDArbLFifS8EMBjolkTJ3po2IMtDGwNJOwuMQzs07479ZUXwc2FCutCDnFjNA6hUFjsDw3nZUuw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DvvByz5/; 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="DvvByz5/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 613A31F000C4; Sat, 17 Oct 2026 16:34:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792254882; bh=tcFfRpGX8mGxvuafjMpvFvHP3QPu0aqbfY3/35gbSRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DvvByz5/F2HHSd8gJ8EuhlxZrdfSBj76KBVPGiL7pZfaI2erFRGssxy+3M2tcCFgt uPaPVcXd5cfpdwlYZLmBPTLJviOVKs0TuqiguFg1/Vu8SgS9pySwhTBM/8S4B20Ow7 HK7NN2ucg0m4CqTrd+NYDclI9ZP0/nnmv1WDFclw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christian Borntraeger , Heiko Carstens , Claudio Imbrenda , Sasha Levin Subject: [PATCH 6.12 592/869] KVM: s390: Fix memory corruption by not reinjecting CK machine checks Date: Sat, 17 Oct 2026 17:57:13 +0200 Message-ID: <20261017160052.230999773@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160036.979869304@linuxfoundation.org> References: <20261017160036.979869304@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Borntraeger [ Upstream commit 546dde823a36d7283dcf46127c2f3d093443860f ] 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> Signed-off-by: Sasha Levin --- arch/s390/include/asm/nmi.h | 3 +++ arch/s390/kernel/nmi.c | 5 +---- arch/s390/kvm/interrupt.c | 24 ++++++++---------------- 3 files changed, 12 insertions(+), 20 deletions(-) diff --git a/arch/s390/include/asm/nmi.h b/arch/s390/include/asm/nmi.h index 227466ce9e416..da5a98183cb65 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 __ASSEMBLY__ union mci { diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index fbd218b6fc8e4..e8d65f87a17df 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -279,8 +279,7 @@ 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; } @@ -292,8 +291,6 @@ 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 0f3ad8c80381f..1474a776efa3e 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -2865,9 +2865,7 @@ 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; @@ -2880,20 +2878,14 @@ 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); } -- 2.53.0