linux-kernel - Re: [PATCH v3] crypto: add virtio-crypto driver

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Message-Id: <20161128141244.4defcfa1.cornelia.huck@de.ibm.com>
Date:   Mon, 28 Nov 2016 14:12:44 +0100
From:   Cornelia Huck <cornelia.huck@...ibm.com>
To:     Gonglei <arei.gonglei@...wei.com>
Cc:     <linux-kernel@...r.kernel.org>, <qemu-devel@...gnu.org>,
        <virtio-dev@...ts.oasis-open.org>,
        <virtualization@...ts.linux-foundation.org>,
        <linux-crypto@...r.kernel.org>, <luonengjun@...wei.com>,
        <mst@...hat.com>, <stefanha@...hat.com>,
        <weidong.huang@...wei.com>, <wu.wubin@...wei.com>,
        <xin.zeng@...el.com>, <claudio.fontana@...wei.com>,
        <herbert@...dor.apana.org.au>, <pasic@...ux.vnet.ibm.com>,
        <davem@...emloft.net>, <jianjay.zhou@...wei.com>,
        <hanweidong@...wei.com>, <arei.gonglei@...mail.com>,
        <xuquan8@...wei.com>, <longpeng2@...wei.com>,
        <salvatore.benedetto@...el.com>
Subject: Re: [PATCH v3] crypto: add virtio-crypto driver

On Mon, 28 Nov 2016 20:08:23 +0800
Gonglei <arei.gonglei@...wei.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;
> +}
> +