KVM: convert bus to slots_lock

Use slots_lock to protect device list on the bus.  slots_lock is already
taken for read everywhere, so we only need to take it for write when
registering devices.  This is in preparation to removing in_range and
kvm->lock around it.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 13 insertions, 3 deletions

diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index b40946c1237d..7b7cc9fe5ee3 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -102,7 +102,7 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
         kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
         dev->kvm = kvm;
         kvm->coalesced_mmio_dev = dev;
-        kvm_io_bus_register_dev(&kvm->mmio_bus, &dev->dev);
+        kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &dev->dev);
 
         return 0;
 }
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 0532fa68f5d1..0eca54e06326 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -343,7 +343,7 @@ int kvm_ioapic_init(struct kvm *kvm)
         kvm_ioapic_reset(ioapic);
         kvm_iodevice_init(&ioapic->dev, &ioapic_mmio_ops);
         ioapic->kvm = kvm;
-        kvm_io_bus_register_dev(&kvm->mmio_bus, &ioapic->dev);
+        kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &ioapic->dev);
         return 0;
 }
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index bbb4029d7c4d..0edc366ecf89 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2527,7 +2527,17 @@ struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus,
         return NULL;
 }
 
-void kvm_io_bus_register_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev)
+void kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
+                             struct kvm_io_device *dev)
+{
+        down_write(&kvm->slots_lock);
+        __kvm_io_bus_register_dev(bus, dev);
+        up_write(&kvm->slots_lock);
+}
+
+/* An unlocked version. Caller must have write lock on slots_lock. */
+void __kvm_io_bus_register_dev(struct kvm_io_bus *bus,
+                             struct kvm_io_device *dev)
 {
         BUG_ON(bus->dev_count > (NR_IOBUS_DEVS-1));