Re: [PATCH v4 26/27] hw/char/virtio-serial: Do not expose the 'emergency-write' property

[Mark Cave-Ayland <mark.caveayland@nutanix.com>]

On 08/05/2025 14:35, Philippe Mathieu-Daudé wrote:

> The VIRTIO_CONSOLE_F_EMERG_WRITE feature bit was only set
> in the hw_compat_2_7[] array, via the 'emergency-write=off'
> property. We removed all machines using that array, lets remove
> that property. All instances have this feature bit set and
> it can not be disabled. VirtIOSerial::host_features mask is
> now unused, remove it.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   include/hw/virtio/virtio-serial.h | 2 --
>   hw/char/virtio-serial-bus.c       | 9 +++------
>   2 files changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/include/hw/virtio/virtio-serial.h b/include/hw/virtio/virtio-serial.h
> index d87c62eab7a..e6ceacec309 100644
> --- a/include/hw/virtio/virtio-serial.h
> +++ b/include/hw/virtio/virtio-serial.h
> @@ -185,8 +185,6 @@ struct VirtIOSerial {
>       struct VirtIOSerialPostLoad *post_load;
>   
>       virtio_serial_conf serial;
> -
> -    uint64_t host_features;
>   };
>   
>   /* Interface to the virtio-serial bus */
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index eb79f5258b6..cfc8fa42186 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -557,7 +557,7 @@ static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
>   
>       vser = VIRTIO_SERIAL(vdev);
>   
> -    features |= vser->host_features;
> +    features |= BIT_ULL(VIRTIO_CONSOLE_F_EMERG_WRITE);
>       if (vser->bus.max_nr_ports > 1) {
>           virtio_add_feature(&features, VIRTIO_CONSOLE_F_MULTIPORT);
>       }
> @@ -587,8 +587,7 @@ static void set_config(VirtIODevice *vdev, const uint8_t *config_data)
>       VirtIOSerialPortClass *vsc;
>       uint8_t emerg_wr_lo;
>   
> -    if (!virtio_has_feature(vser->host_features,
> -        VIRTIO_CONSOLE_F_EMERG_WRITE) || !config->emerg_wr) {
> +    if (!config->emerg_wr) {
>           return;
>       }
>   
> @@ -1039,7 +1038,7 @@ static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
>           return;
>       }
>   
> -    if (!virtio_has_feature(vser->host_features,
> +    if (!virtio_has_feature(vdev->host_features,
>                               VIRTIO_CONSOLE_F_EMERG_WRITE)) {
>           config_size = offsetof(struct virtio_console_config, emerg_wr);
>       }
> @@ -1155,8 +1154,6 @@ static const VMStateDescription vmstate_virtio_console = {
>   static const Property virtio_serial_properties[] = {
>       DEFINE_PROP_UINT32("max_ports", VirtIOSerial, serial.max_virtserial_ports,
>                                                     31),
> -    DEFINE_PROP_BIT64("emergency-write", VirtIOSerial, host_features,
> -                      VIRTIO_CONSOLE_F_EMERG_WRITE, true),
>   };
>   
>   static void virtio_serial_class_init(ObjectClass *klass, const void *data)

LGTM.

Reviewed-by: Mark Cave-Ayland <mark.caveayland@nutanix.com>


ATB,

Mark.