[PATCH v4 08/13] KVM: s390: Free the mmu cache when kvm_arch_vcpu_create() fails

[Claudio Imbrenda]

The mmu cache is the first thing that is allocated in
kvm_arch_vcpu_create(), but in case of failure it was not freed.

Fix by freeing the mmu cache in case of failure.

Refactor kvm_arch_vcpu_create() to use scope-based cleanup instead of
gotos.

Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
---
 arch/s390/kvm/kvm-s390.c | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 47eba1664bec..776dfa0ef970 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3795,21 +3795,21 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
 	return 0;
 }
 
+DEFINE_FREE(sie_page, struct sie_page *, if (_T) free_page((unsigned long)(_T)))
+
 int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 {
-	struct sie_page *sie_page;
+	struct kvm_s390_mmu_cache *mc __free(kvm_s390_mmu_cache) = NULL;
+	struct sie_page *sie_page __free(sie_page) = NULL;
 	int rc;
 
 	BUILD_BUG_ON(sizeof(struct sie_page) != 4096);
-	vcpu->arch.mc = kvm_s390_new_mmu_cache();
-	if (!vcpu->arch.mc)
+	mc = kvm_s390_new_mmu_cache();
+	if (!mc)
 		return -ENOMEM;
 	sie_page = (struct sie_page *) get_zeroed_page(GFP_KERNEL_ACCOUNT);
-	if (!sie_page) {
-		kvm_s390_free_mmu_cache(vcpu->arch.mc);
-		vcpu->arch.mc = NULL;
+	if (!sie_page)
 		return -ENOMEM;
-	}
 
 	vcpu->arch.sie_block = &sie_page->sie_block;
 	vcpu->arch.sie_block->itdba = virt_to_phys(&sie_page->itdb);
@@ -3851,10 +3851,9 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 		vcpu->run->kvm_valid_regs |= KVM_SYNC_FPRS;
 
 	if (kvm_is_ucontrol(vcpu->kvm)) {
-		rc = -ENOMEM;
 		vcpu->arch.gmap = gmap_new_child(vcpu->kvm->arch.gmap, -1UL);
 		if (!vcpu->arch.gmap)
-			goto out_free_sie_block;
+			return -ENOMEM;
 	}
 
 	VM_EVENT(vcpu->kvm, 3, "create cpu %d at 0x%p, sie block at 0x%p",
@@ -3862,22 +3861,19 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	trace_kvm_s390_create_vcpu(vcpu->vcpu_id, vcpu, vcpu->arch.sie_block);
 
 	rc = kvm_s390_vcpu_setup(vcpu);
-	if (rc)
-		goto out_ucontrol_uninit;
+	if (rc) {
+		if (kvm_is_ucontrol(vcpu->kvm)) {
+			scoped_guard(spinlock, &vcpu->kvm->arch.gmap->children_lock)
+				gmap_remove_child(vcpu->arch.gmap);
+			vcpu->arch.gmap = gmap_put(vcpu->arch.gmap);
+		}
+		return rc;
+	}
 
+	vcpu->arch.mc = no_free_ptr(mc);
+	sie_page = NULL;
 	kvm_s390_update_topology_change_report(vcpu->kvm, 1);
 	return 0;
-
-out_ucontrol_uninit:
-	if (kvm_is_ucontrol(vcpu->kvm)) {
-		spin_lock(&vcpu->kvm->arch.gmap->children_lock);
-		gmap_remove_child(vcpu->arch.gmap);
-		spin_unlock(&vcpu->kvm->arch.gmap->children_lock);
-		vcpu->arch.gmap = gmap_put(vcpu->arch.gmap);
-	}
-out_free_sie_block:
-	free_page((unsigned long)(vcpu->arch.sie_block));
-	return rc;
 }
 
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
-- 
2.55.0