Re: [PATCH 4/8] virtio: categorize callbacks in GS

[Michael S. Tsirkin]

On Thu, Jun 09, 2022 at 10:37:23AM -0400, Emanuele Giuseppe Esposito wrote:
> All the callbacks below are always running in the main loop.
> 
> The callbacks are the following:
> - start/stop_ioeventfd: these are the callbacks where
>   blk_set_aio_context(iothread) is done, so they are called in the main
>   loop.
> 
> - save and load: called during migration, when VM is stopped from the
>   main loop.
> 
> - reset: before calling this callback, stop_ioeventfd is invoked, so
>   it can only run in the main loop.
> 
> - set_status: going through all the callers we can see it is called
>   from a MemoryRegionOps callback, which always run in the main loop.
> 
> - realize: iothread is not even created yet.
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>


> ---
>  hw/block/virtio-blk.c  | 2 ++
>  hw/virtio/virtio-bus.c | 5 +++++
>  hw/virtio/virtio-pci.c | 2 ++
>  hw/virtio/virtio.c     | 8 ++++++++
>  4 files changed, 17 insertions(+)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 29a9c53ebc..4e6421c35e 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -1032,6 +1032,8 @@ static void virtio_blk_set_status(VirtIODevice *vdev, 
> uint8_t status)
>  {
>      VirtIOBlock *s = VIRTIO_BLK(vdev);
>  
> +    GLOBAL_STATE_CODE();
> +
>      if (!(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) {
>          assert(!s->dataplane_started);
>      }
> diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
> index d7ec023adf..0891ddb2ff 100644
> --- a/hw/virtio/virtio-bus.c
> +++ b/hw/virtio/virtio-bus.c
> @@ -23,6 +23,7 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qemu/main-loop.h"
>  #include "qemu/error-report.h"
>  #include "qemu/module.h"
>  #include "qapi/error.h"
> @@ -223,6 +224,8 @@ int virtio_bus_start_ioeventfd(VirtioBusState *bus)
>      VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
>      int r;
>  
> +    GLOBAL_STATE_CODE();
> +
>      if (!k->ioeventfd_assign || !k->ioeventfd_enabled(proxy)) {
>          return -ENOSYS;
>      }
> @@ -247,6 +250,8 @@ void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
>      VirtIODevice *vdev;
>      VirtioDeviceClass *vdc;
>  
> +    GLOBAL_STATE_CODE();
> +
>      if (!bus->ioeventfd_started) {
>          return;
>      }
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 0566ad7d00..6798039391 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -301,6 +301,8 @@ static void virtio_ioport_write(void *opaque, uint32_t 
> addr, uint32_t val)
>      VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
>      hwaddr pa;
>  
> +    GLOBAL_STATE_CODE();
> +
>      switch (addr) {
>      case VIRTIO_PCI_GUEST_FEATURES:
>          /* Guest does not negotiate properly?  We have to assume nothing. */
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 5d607aeaa0..2650504dd4 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1977,6 +1977,8 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val)
>      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>      trace_virtio_set_status(vdev, val);
>  
> +    GLOBAL_STATE_CODE();
> +
>      if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
>          if (!(vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) &&
>              val & VIRTIO_CONFIG_S_FEATURES_OK) {
> @@ -2025,6 +2027,8 @@ void virtio_reset(void *opaque)
>      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>      int i;
>  
> +    GLOBAL_STATE_CODE();
> +
>      virtio_set_status(vdev, 0);
>      if (current_cpu) {
>          /* Guest initiated reset */
> @@ -2882,6 +2886,8 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f)
>      uint32_t guest_features_lo = (vdev->guest_features & 0xffffffff);
>      int i;
>  
> +    GLOBAL_STATE_CODE();
> +
>      if (k->save_config) {
>          k->save_config(qbus->parent, f);
>      }
> @@ -3024,6 +3030,8 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int 
> version_id)
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>      VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
>  
> +    GLOBAL_STATE_CODE();
> +
>      /*
>       * We poison the endianness to ensure it does not get used before
>       * subsections have been loaded.
> -- 
> 2.31.1