On confidential guests when the KVM virtual machine file descriptor changes as
a part of the reset process, event file descriptors needs to be reassociated
with the new KVM VM file descriptor. This is achieved with the help of a
callback handler that gets called when KVM VM file descriptor changes during
the confidential guest reset process.
This patch is untested on confidential guests and only exists for completeness.
Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
hw/hyperv/vmbus.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c
index c5bab5d245..947fb7f4f8 100644
--- a/hw/hyperv/vmbus.c
+++ b/hw/hyperv/vmbus.c
@@ -20,6 +20,7 @@
#include "hw/hyperv/vmbus-bridge.h"
#include "hw/core/sysbus.h"
#include "exec/cpu-common.h"
+#include "system/kvm.h"
#include "exec/target_page.h"
#include "trace.h"
@@ -248,6 +249,12 @@ struct VMBus {
* interrupt page
*/
EventNotifier notifier;
+
+ /*
+ * Notifier to inform when vmfd is changed as a part of confidential guest
+ * reset mechanism.
+ */
+ NotifierWithReturn vmbus_vmfd_change_notifier;
};
static bool gpadl_full(VMBusGpadl *gpadl)
@@ -2347,6 +2354,26 @@ static void vmbus_dev_unrealize(DeviceState *dev)
free_channels(vdev);
}
+/*
+ * If the KVM fd changes because of VM reset in confidential guests,
+ * reassociate event fd with the new KVM fd.
+ */
+static int vmbus_handle_vmfd_change(NotifierWithReturn *notifier,
+ void *data, Error** errp)
+{
+ VMBus *vmbus = container_of(notifier, VMBus,
+ vmbus_vmfd_change_notifier);
+ int ret = 0;
+ ret = hyperv_set_event_flag_handler(VMBUS_EVENT_CONNECTION_ID,
+ &vmbus->notifier);
+ /* if we are only using userland event handler, it may already exist */
+ if (ret != 0 && ret != -EEXIST) {
+ error_setg(errp, "hyperv set event handler failed with %d", ret);
+ }
+
+ return ret;
+}
+
static const Property vmbus_dev_props[] = {
DEFINE_PROP_UUID("instanceid", VMBusDevice, instanceid),
};
@@ -2429,6 +2456,9 @@ static void vmbus_realize(BusState *bus, Error **errp)
goto clear_event_notifier;
}
+ vmbus->vmbus_vmfd_change_notifier.notify = vmbus_handle_vmfd_change;
+ kvm_vmfd_add_change_notifier(&vmbus->vmbus_vmfd_change_notifier);
+
return;
clear_event_notifier:
--
2.42.0