[PATCH v3 2/4] KVM: Use goto to handle errors during memslot preparation

[Sean Christopherson <seanjc@google.com>]

Use a goto to unwind early memslot changes if preparing for a memslot
operation fails.  This will allow moving the creation of guest_memfd
bindings into kvm_set_memslot() without needing to copy+paste the unwind
logic.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 virt/kvm/kvm_main.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 65eb26a0520d..3c0dbe60a5b4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1931,21 +1931,8 @@ static int kvm_set_memslot(struct kvm *kvm,
 	}
 
 	r = kvm_prepare_memory_region(kvm, old, new, change);
-	if (r) {
-		/*
-		 * For DELETE/MOVE, revert the above INVALID change.  No
-		 * modifications required since the original slot was preserved
-		 * in the inactive slots.  Changing the active memslots also
-		 * release slots_arch_lock.
-		 */
-		if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
-			kvm_activate_memslot(kvm, invalid_slot, old);
-			kfree(invalid_slot);
-		} else {
-			mutex_unlock(&kvm->slots_arch_lock);
-		}
-		return r;
-	}
+	if (r)
+		goto err;
 
 	/*
 	 * For DELETE and MOVE, the working slot is now active as the INVALID
@@ -1977,6 +1964,20 @@ static int kvm_set_memslot(struct kvm *kvm,
 	kvm_commit_memory_region(kvm, old, new, change);
 
 	return 0;
+
+err:
+	/*
+	 * For DELETE/MOVE, revert the above INVALID change.  No modifications
+	 * required since the original slot was preserved in the inactive slots.
+	 * Changing the active memslots also release slots_arch_lock.
+	 */
+	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
+		kvm_activate_memslot(kvm, invalid_slot, old);
+		kfree(invalid_slot);
+	} else {
+		mutex_unlock(&kvm->slots_arch_lock);
+	}
+	return r;
 }
 
 static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
-- 
2.55.0.979.g7e5102b832-goog