From: Sean Christopherson <seanjc@google.com>
Date: Mon, 12 Apr 2021 15:20:50 -0700
Subject: KVM: Add proper lockdep assertion in I/O bus unregister
Git-commit: 7c896d375565a032705f64804f8c1189df1f7a89
Patch-mainline: v5.13-rc1
References: CVE-2020-36312 bsc#1184509

Convert a comment above kvm_io_bus_unregister_dev() into an actual
lockdep assertion, and opportunistically add curly braces to a multi-line
for-loop.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210412222050.876100-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 virt/kvm/kvm_main.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3705,21 +3705,23 @@ int kvm_io_bus_register_dev(struct kvm *
 	return 0;
 }
 
-/* Caller must hold slots_lock. */
 int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
 			      struct kvm_io_device *dev)
 {
 	int i, j;
 	struct kvm_io_bus *new_bus, *bus;
 
+	lockdep_assert_held(&kvm->slots_lock);
+
 	bus = kvm_get_bus(kvm, bus_idx);
 	if (!bus)
 		return 0;
 
-	for (i = 0; i < bus->dev_count; i++)
+	for (i = 0; i < bus->dev_count; i++) {
 		if (bus->range[i].dev == dev) {
 			break;
 		}
+	}
 
 	if (i == bus->dev_count)
 		return 0;