Re: [PATCH] virtio: disable ioeventfd for record/replay

[Pavel Dovgalyuk]

ping

On 17.05.2021 16:06, Pavel Dovgalyuk wrote:
> virtio devices support separate iothreads waiting for
> events from file descriptors. These are asynchronous
> events that can't be recorded and replayed, therefore
> this patch disables ioeventfd for all devices when
> record or replay is enabled.
>
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> ---
>   hw/s390x/virtio-ccw.c   |    6 ++++++
>   hw/virtio/virtio-mmio.c |    6 ++++++
>   hw/virtio/virtio-pci.c  |    6 ++++++
>   3 files changed, 18 insertions(+)
>
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index 92b950e09a..bd8b9c5755 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -31,6 +31,7 @@
>   #include "trace.h"
>   #include "hw/s390x/css-bridge.h"
>   #include "hw/s390x/s390-virtio-ccw.h"
> +#include "sysemu/replay.h"
>   
>   #define NR_CLASSIC_INDICATOR_BITS 64
>   
> @@ -769,6 +770,11 @@ static void virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
>           dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
>       }
>   
> +    /* fd-based ioevents can't be synchronized in record/replay */
> +    if (replay_mode != REPLAY_MODE_NONE) {
> +        dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
> +    }
> +
>       if (k->realize) {
>           k->realize(dev, &err);
>           if (err) {
> diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
> index 5952471b38..1af48a1b04 100644
> --- a/hw/virtio/virtio-mmio.c
> +++ b/hw/virtio/virtio-mmio.c
> @@ -29,6 +29,7 @@
>   #include "qemu/host-utils.h"
>   #include "qemu/module.h"
>   #include "sysemu/kvm.h"
> +#include "sysemu/replay.h"
>   #include "hw/virtio/virtio-mmio.h"
>   #include "qemu/error-report.h"
>   #include "qemu/log.h"
> @@ -740,6 +741,11 @@ static void virtio_mmio_realizefn(DeviceState *d, Error 
> **errp)
>           proxy->flags &= ~VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD;
>       }
>   
> +    /* fd-based ioevents can't be synchronized in record/replay */
> +    if (replay_mode != REPLAY_MODE_NONE) {
> +        proxy->flags &= ~VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD;
> +    }
> +
>       if (proxy->legacy) {
>           memory_region_init_io(&proxy->iomem, OBJECT(d),
>                                 &virtio_legacy_mem_ops, proxy,
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index b321604d9b..f1e105fa52 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -37,6 +37,7 @@
>   #include "qemu/range.h"
>   #include "hw/virtio/virtio-bus.h"
>   #include "qapi/visitor.h"
> +#include "sysemu/replay.h"
>   
>   #define VIRTIO_PCI_REGION_SIZE(dev)     VIRTIO_PCI_CONFIG_OFF(msix_present(dev))
>   
> @@ -1760,6 +1761,11 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
>           proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
>       }
>   
> +    /* fd-based ioevents can't be synchronized in record/replay */
> +    if (replay_mode != REPLAY_MODE_NONE) {
> +        proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
> +    }
> +
>       /*
>        * virtio pci bar layout used by default.
>        * subclasses can re-arrange things if needed.