Re: [Qemu-devel] [PATCH v3] crypto: add virtio-crypto driver

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Mon, 28 Nov 2016 20:08:23 +0800
Gonglei <arei.gonglei@huawei.com> wrote:

> +static int virtcrypto_update_status(struct virtio_crypto *vcrypto)
> +{
> +	u32 status;
> +	int err;
> +
> +	virtio_cread(vcrypto->vdev,
> +	    struct virtio_crypto_config, status, &status);
> +
> +	/* Ignore unknown (future) status bits */
> +	status &= VIRTIO_CRYPTO_S_HW_READY;

I'm wondering what the driver really should do if it encounters unknown
status bits.

I'd expect that new status bits are guarded by a feature bit and that
the device should not set status bits if the respective feature bit has
not been negotiated. Therefore, unknown status bits would be a host
error and the driver should consider the device to be broken.

Thoughts?

> +
> +	if (vcrypto->status == status)
> +		return 0;
> +
> +	vcrypto->status = status;
> +
> +	if (vcrypto->status & VIRTIO_CRYPTO_S_HW_READY) {
> +		err = virtcrypto_dev_start(vcrypto);
> +		if (err) {
> +			dev_err(&vcrypto->vdev->dev,
> +				"Failed to start virtio crypto device.\n");
> +			virtcrypto_dev_stop(vcrypto);
> +			return -EPERM;
> +		}
> +		dev_info(&vcrypto->vdev->dev, "Accelerator is ready\n");
> +	} else {
> +		virtcrypto_dev_stop(vcrypto);
> +		dev_info(&vcrypto->vdev->dev, "Accelerator is not ready\n");
> +	}
> +
> +	return 0;
> +}
> +