[PATCH v3 09/10] KVM: s390: Fix possible reference leak in fault-in code

[Claudio Imbrenda]

If kvm_s390_new_mmu_cache() fails, kvm_s390_faultin_gfn() returns
without releasing the faulted page.

Fix this by moving the allocation of the memory cache outside of the
loop. There is no reason to check at every iteration.

Opportunistically fix a comment.

Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
---
 arch/s390/kvm/faultin.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/s390/kvm/faultin.c b/arch/s390/kvm/faultin.c
index cf542b0a7e8e..fee80047bd94 100644
--- a/arch/s390/kvm/faultin.c
+++ b/arch/s390/kvm/faultin.c
@@ -54,6 +54,13 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa
 			return 0;
 	}
 
+	if (!mc) {
+		local_mc = kvm_s390_new_mmu_cache();
+		if (!local_mc)
+			return -ENOMEM;
+		mc = local_mc;
+	}
+
 	while (rc == -EAGAIN) {
 		f->valid = false;
 		inv_seq = kvm->mmu_invalidate_seq;
@@ -94,14 +101,7 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa
 		if (is_error_pfn(f->pfn))
 			return -EFAULT;
 
-		if (!mc) {
-			local_mc = kvm_s390_new_mmu_cache();
-			if (!local_mc)
-				return -ENOMEM;
-			mc = local_mc;
-		}
-
-		/* Loop, will automatically release the faulted page. */
+		/* Loop, release the faulted page. */
 		if (mmu_invalidate_retry_gfn_unsafe(kvm, inv_seq, f->gfn)) {
 			kvm_release_faultin_page(kvm, f->page, true, false);
 			continue;
-- 
2.54.0