ioport: Fail when registering overlapping ports

If we try to register a range of ports which overlaps with another, already
registered, I/O ports region then device emulation for that region will not
work anymore. There's nothing sane that the ioport emulation layer can do
in this case so refuse to allocate the port. This matches the behavior of
kvm__register_mmio.

There's no need to protect allocating a new ioport struct with a lock, so
move the lock to protect the actual ioport insertion in the tree.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 1 insertions, 8 deletions

diff --git a/ioport.c b/ioport.c
index cb778ed8..d9f2e8ea 100644
--- a/ioport.c
+++ b/ioport.c
@@ -68,14 +68,6 @@ int ioport__register(struct kvm *kvm, u16 port, struct ioport_operations *ops, i
 	struct ioport *entry;
 	int r;
 
-	br_write_lock(kvm);
-
-	entry = ioport_search(&ioport_tree, port);
-	if (entry) {
-		pr_warning("ioport re-registered: %x", port);
-		ioport_remove(&ioport_tree, entry);
-	}
-
 	entry = malloc(sizeof(*entry));
 	if (entry == NULL)
 		return -ENOMEM;
@@ -90,6 +82,7 @@ int ioport__register(struct kvm *kvm, u16 port, struct ioport_operations *ops, i
 		},
 	};
 
+	br_write_lock(kvm);
 	r = ioport_insert(&ioport_tree, entry);
 	if (r < 0)
 		goto out_free;