diff options
| author | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2026-07-02 17:23:59 +0200 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@linux.ibm.com> | 2026-07-09 10:26:10 +0200 |
| commit | 866d03de6def89c386cdfd457b28a1f566e02565 (patch) | |
| tree | 2d668ec30c90ab4630b1fe64654cbbe5d06eb864 | |
| parent | 7b69729046a4c58f4cb457184e5ac4aaa179bff4 (diff) | |
KVM: s390: vsie: Avoid potential deadlock with real spaces
The natural lock ordering is mmu_lock -> children_lock, but in
gmap_create_shadow() the reverse order is used when handling shadowing
of real address spaces.
Convert the inner locking of kvm->mmu_lock to a trylock; return -EAGAIN
if the lock is busy, and let the caller try again.
This path is not expected to happen in real-life scenarios, so its
performance is not important.
Fixes: a2c17f9270cc ("KVM: s390: New gmap code")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
| -rw-r--r-- | arch/s390/kvm/gmap.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c index 298fbaecec28..8abb4f55b306 100644 --- a/arch/s390/kvm/gmap.c +++ b/arch/s390/kvm/gmap.c @@ -1374,8 +1374,13 @@ struct gmap *gmap_create_shadow(struct kvm_s390_mmu_cache *mc, struct gmap *pare /* Only allow one real-space gmap shadow. */ list_for_each_entry(sg, &parent->children, list) { if (sg->guest_asce.r) { - scoped_guard(write_lock, &parent->kvm->mmu_lock) + if (write_trylock(&parent->kvm->mmu_lock)) { gmap_unshadow(sg); + write_unlock(&parent->kvm->mmu_lock); + } else { + gmap_put(new); + return ERR_PTR(-EAGAIN); + } break; } } |