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

[Cornelia Huck]

On Thu, 11 Feb 2021 11:34:53 +0300
Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru> 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/virtio/virtio-pci.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 094c36aa3e..76fbc111ea 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))
>  
> @@ -1746,6 +1747,11 @@ 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.
> 
> 

I think you would need to do the same for any device using ioeventfd,
no?