KVM: s390: Fix handle_{sske,pfmf} under memory pressure

Under heavy memory pressure, handle_sske() and handle_pfmf() might
cause an endless loop if the mmu cache runs empty, the atomic
allocations fail, and the top-up function also fails. While quite
unlikely, that scenario is not impossible.

Fix the issue by not ignoring the return value of
kvm_s390_mmu_cache_topup(), and appropriately returning an error code
in case of failure.

Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-6-imbrenda@linux.ibm.com>

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 447ec7ed423dc45dd29ff437cbb9c167ce806dd3..9bc6fd02ff77702cf4213b096c3b5b1e6d240968 100644 (file)
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -366,7 +366,9 @@ static int handle_sske(struct kvm_vcpu *vcpu)
                if (rc > 1)
                        return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
                if (rc == -ENOMEM) {
-                       kvm_s390_mmu_cache_topup(vcpu->arch.mc);
+                       rc = kvm_s390_mmu_cache_topup(vcpu->arch.mc);
+                       if (rc)
+                               return rc;
                        continue;
                }
                if (rc < 0)
@@ -1122,7 +1124,9 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
                        if (rc > 1)
                                return kvm_s390_inject_program_int(vcpu, rc);
                        if (rc == -ENOMEM) {
-                               kvm_s390_mmu_cache_topup(vcpu->arch.mc);
+                               rc = kvm_s390_mmu_cache_topup(vcpu->arch.mc);
+                               if (rc)
+                                       return rc;
                                continue;
                        }
                        if (rc < 0)