Re: [PATCH 1/2] pc-bios/s390-ccw/virtio: Set missing status bits while initializing

[Christian Borntraeger <borntraeger@linux.ibm.com>]

Am 23.06.22 um 09:11 schrieb Thomas Huth:
> According chapter "3.1.1 Driver Requirements: Device Initialization"
> of the Virtio specification (v1.1), a driver for a device has to set
> the ACKNOWLEDGE and DRIVER bits in the status field after resetting
> the device. The s390-ccw bios skipped these steps so far and seems
> like QEMU never cared. Anyway, it's better to follow the spec, so
> let's set these bits now in the right spots, too.

I have not tested that but I agree with this

Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>


> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>   pc-bios/s390-ccw/virtio.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
> index 5d2c6e3381..4e85a2eb82 100644
> --- a/pc-bios/s390-ccw/virtio.c
> +++ b/pc-bios/s390-ccw/virtio.c
> @@ -220,7 +220,7 @@ int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd)
>   void virtio_setup_ccw(VDev *vdev)
>   {
>       int i, rc, cfg_size = 0;
> -    unsigned char status = VIRTIO_CONFIG_S_DRIVER_OK;
> +    uint8_t status;
>       struct VirtioFeatureDesc {
>           uint32_t features;
>           uint8_t index;
> @@ -234,6 +234,10 @@ void virtio_setup_ccw(VDev *vdev)
>   
>       run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0, false);
>   
> +    status = VIRTIO_CONFIG_S_ACKNOWLEDGE;
> +    rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
> +    IPL_assert(rc == 0, "Could not write ACKNOWLEDGE status to host");
> +
>       switch (vdev->senseid.cu_model) {
>       case VIRTIO_ID_NET:
>           vdev->nr_vqs = 2;
> @@ -253,6 +257,11 @@ void virtio_setup_ccw(VDev *vdev)
>       default:
>           panic("Unsupported virtio device\n");
>       }
> +
> +    status |= VIRTIO_CONFIG_S_DRIVER;
> +    rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
> +    IPL_assert(rc == 0, "Could not write DRIVER status to host");
> +
>       IPL_assert(
>           run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size, false) == 0,
>          "Could not get block device configuration");
> @@ -291,9 +300,10 @@ void virtio_setup_ccw(VDev *vdev)
>               run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info), false) == 0,
>               "Cannot set VQ info");
>       }
> -    IPL_assert(
> -        run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false) == 0,
> -        "Could not write status to host");
> +
> +    status |= VIRTIO_CONFIG_S_DRIVER_OK;
> +    rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
> +    IPL_assert(rc == 0, "Could not write DRIVER_OK status to host");
>   }
>   
>   bool virtio_is_supported(SubChannelId schid)