On Mon, Jan 2, 2023 at 9:08 AM Joelle van Dyne <j...@getutm.app> wrote:
>
> When the VM is stopped using the HMP command "stop", soon the handler will
> stop reading from the vmnet interface. This causes a flood of
> `VMNET_INTERFACE_PACKETS_AVAILABLE` events to arrive and puts the host CPU
> at 100%. We fix this by removing the event handler from vmnet when the VM
> is no longer in a running state and restore it when we return to a running
> state.
>
> Signed-off-by: Joelle van Dyne <j...@getutm.app>
Applied.
Thanks
> ---
> net/vmnet_int.h | 2 ++
> net/vmnet-common.m | 48 +++++++++++++++++++++++++++++++++-------------
> 2 files changed, 37 insertions(+), 13 deletions(-)
>
> diff --git a/net/vmnet_int.h b/net/vmnet_int.h
> index adf6e8c20d..ffba92108f 100644
> --- a/net/vmnet_int.h
> +++ b/net/vmnet_int.h
> @@ -46,6 +46,8 @@ typedef struct VmnetState {
> int packets_send_end_pos;
>
> struct iovec iov_buf[VMNET_PACKETS_LIMIT];
> +
> + VMChangeStateEntry *change;
> } VmnetState;
>
> const char *vmnet_status_map_str(vmnet_return_t status);
> diff --git a/net/vmnet-common.m b/net/vmnet-common.m
> index 2cb60b9ddd..2958283485 100644
> --- a/net/vmnet-common.m
> +++ b/net/vmnet-common.m
> @@ -17,6 +17,7 @@
> #include "clients.h"
> #include "qemu/error-report.h"
> #include "qapi/error.h"
> +#include "sysemu/runstate.h"
>
> #include <vmnet/vmnet.h>
> #include <dispatch/dispatch.h>
> @@ -242,6 +243,35 @@ static void vmnet_bufs_init(VmnetState *s)
> }
> }
>
> +/**
> + * Called on state change to un-register/re-register handlers
> + */
> +static void vmnet_vm_state_change_cb(void *opaque, bool running, RunState
> state)
> +{
> + VmnetState *s = opaque;
> +
> + if (running) {
> + vmnet_interface_set_event_callback(
> + s->vmnet_if,
> + VMNET_INTERFACE_PACKETS_AVAILABLE,
> + s->if_queue,
> + ^(interface_event_t event_id, xpc_object_t event) {
> + assert(event_id == VMNET_INTERFACE_PACKETS_AVAILABLE);
> + /*
> + * This function is being called from a non qemu thread, so
> + * we only schedule a BH, and do the rest of the io
> completion
> + * handling from vmnet_send_bh() which runs in a qemu
> context.
> + */
> + qemu_bh_schedule(s->send_bh);
> + });
> + } else {
> + vmnet_interface_set_event_callback(
> + s->vmnet_if,
> + VMNET_INTERFACE_PACKETS_AVAILABLE,
> + NULL,
> + NULL);
> + }
> +}
>
> int vmnet_if_create(NetClientState *nc,
> xpc_object_t if_desc,
> @@ -329,19 +359,9 @@ int vmnet_if_create(NetClientState *nc,
> s->packets_send_current_pos = 0;
> s->packets_send_end_pos = 0;
>
> - vmnet_interface_set_event_callback(
> - s->vmnet_if,
> - VMNET_INTERFACE_PACKETS_AVAILABLE,
> - s->if_queue,
> - ^(interface_event_t event_id, xpc_object_t event) {
> - assert(event_id == VMNET_INTERFACE_PACKETS_AVAILABLE);
> - /*
> - * This function is being called from a non qemu thread, so
> - * we only schedule a BH, and do the rest of the io completion
> - * handling from vmnet_send_bh() which runs in a qemu context.
> - */
> - qemu_bh_schedule(s->send_bh);
> - });
> + vmnet_vm_state_change_cb(s, 1, RUN_STATE_RUNNING);
> +
> + s->change = qemu_add_vm_change_state_handler(vmnet_vm_state_change_cb,
> s);
>
> return 0;
> }
> @@ -356,6 +376,8 @@ void vmnet_cleanup_common(NetClientState *nc)
> return;
> }
>
> + vmnet_vm_state_change_cb(s, 0, RUN_STATE_SHUTDOWN);
> + qemu_del_vm_change_state_handler(s->change);
> if_stopped_sem = dispatch_semaphore_create(0);
> vmnet_stop_interface(
> s->vmnet_if,
> --
> 2.28.0
>
