[PATCH v3 0/2] KVM: s390: Fix two bugs

From: Claudio Imbrenda
Date: Mon Aug 25 2025 - 11:18:58 EST


This small series fixes two bugs in s390 KVM. One is small and trivial,
the other is pretty bad.

* The wrong type of flag was being passed to vcpu_dat_fault_handler();
it expects a FOLL_* flag, but a FAULT_FLAG_* was passed instead.
* Due to incorrect usage of mmu_notifier_register(), in some rare cases
when running a secure guest, the struct mm for the userspace process
would get freed too early and cause a use-after-free.

v2->v3
* Make sure .ops is not NULL before calling mmu_notifier_register() to
avoid NULL pointer errors (thanks Marc)
v1->v2
* Rename the parameters of __kvm_s390_handle_dat_fault() and
vcpu_dat_fault_handler() from flags to foll (thanks Christian)

Claudio Imbrenda (2):
KVM: s390: Fix incorrect usage of mmu_notifier_register()
KVM: s390: Fix FOLL_*/FAULT_FLAG_* confusion

arch/s390/kvm/kvm-s390.c | 24 ++++++++++++------------
arch/s390/kvm/pv.c | 16 +++++++++++-----
2 files changed, 23 insertions(+), 17 deletions(-)

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2.51.0