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 tested on non-confidential platform only. Signed-off-by: Ani Sinha <[email protected]> --- hw/hyperv/trace-events | 1 + hw/hyperv/vmbus.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/hw/hyperv/trace-events b/hw/hyperv/trace-events index 7963c215b1..d8c96f18e9 100644 --- a/hw/hyperv/trace-events +++ b/hw/hyperv/trace-events @@ -16,6 +16,7 @@ vmbus_gpadl_torndown(uint32_t gpadl_id) "gpadl #%d" vmbus_open_channel(uint32_t chan_id, uint32_t gpadl_id, uint32_t target_vp) "channel #%d gpadl #%d target vp %d" vmbus_channel_open(uint32_t chan_id, uint32_t status) "channel #%d status %d" vmbus_close_channel(uint32_t chan_id) "channel #%d" +vmbus_handle_vmfd_change(void) "" # hv-balloon hv_balloon_state_change(const char *tostr) "-> %s" diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c index c5bab5d245..64abe4c4c1 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 +2354,33 @@ 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; + + /* we are not interested in pre vmfd change notification */ + if (((VmfdChangeNotifier *)data)->pre) { + return 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); + } + + trace_vmbus_handle_vmfd_change(); + return ret; +} + static const Property vmbus_dev_props[] = { DEFINE_PROP_UUID("instanceid", VMBusDevice, instanceid), }; @@ -2429,6 +2463,9 @@ 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
