From b239410c7653ff6781d4cf1d63cfc52a1bb71788 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Wed, 5 Aug 2026 13:04:50 +0200 Subject: [PATCH] KVM: s390: Zero initialize irq in reinject_machine_check kvm_s390_reinject_machine_check() fills cr14, mcic, ext_damage_code and failing_storage_address of the on-stack struct kvm_s390_irq, but struct kvm_s390_mchk_info also has a pad word and a 16 byte fixed_logout array. struct mcck_volatile_info carries no logout data, so there is nothing to copy there and both stay whatever was on the stack. __inject_mchk() then memcpy()s fixed_logout into the vcpu local interrupt state unconditionally. This will reach the guest during deliver and userspace during migration. Reflecting zeroes is the correct behaviour here, as KVM has no logout data for a reinjected machine check. This needs a host machine check while the cpu is in SIE so not trivial to trigger. Fixes: 4d62fcc0b692 ("KVM: s390: Inject machine check into the guest") Cc: stable@vger.kernel.org Signed-off-by: Christian Borntraeger Reviewed-by: Matthew Rosato Reviewed-by: Claudio Imbrenda Signed-off-by: Claudio Imbrenda Message-ID: <20260805110455.7200-4-borntraeger@linux.ibm.com> --- arch/s390/kvm/interrupt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 23f0e0821474..009d6a845d59 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -3109,7 +3109,7 @@ 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_irq irq = {}; struct kvm_s390_mchk_info *mchk; union mci mci; __u64 cr14 = 0; /* upper bits are not used */