linux-kernel - Re: [PATCH v2 1/9] crypto: virtio: Add spinlock protection with virtqueue notification

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Message-ID: <CACGkMEsjhw2=XCFH6qoYu60NjTf-DJ-oaB89qjaeWpsk+5t6JQ@mail.gmail.com>
Date: Fri, 5 Dec 2025 09:21:45 +0800
From: Jason Wang <jasowang@...hat.com>
To: Bibo Mao <maobibo@...ngson.cn>
Cc: Gonglei <arei.gonglei@...wei.com>, "Michael S. Tsirkin" <mst@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez <eperezma@...hat.com>, 
	Herbert Xu <herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>, 
	wangyangxin <wangyangxin1@...wei.com>, stable@...r.kernel.org, 
	virtualization@...ts.linux.dev, linux-crypto@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/9] crypto: virtio: Add spinlock protection with
 virtqueue notification

On Thu, Dec 4, 2025 at 7:22 PM Bibo Mao <maobibo@...ngson.cn> wrote:
>
> When VM boots with one virtio-crypto PCI device and builtin backend,
> run openssl benchmark command with multiple processes, such as
>   openssl speed -evp aes-128-cbc -engine afalg  -seconds 10 -multi 32
>
> openssl processes will hangup and there is error reported like this:
>  virtio_crypto virtio0: dataq.0:id 3 is not a head!
>
> It seems that the data virtqueue need protection when it is handled
> for virtio done notification. If the spinlock protection is added
> in virtcrypto_done_task(), openssl benchmark with multiple processes
> works well.
>
> Fixes: fed93fb62e05 ("crypto: virtio - Handle dataq logic with tasklet")
> Cc: stable@...r.kernel.org
> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
> ---
>  drivers/crypto/virtio/virtio_crypto_core.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/crypto/virtio/virtio_crypto_core.c b/drivers/crypto/virtio/virtio_crypto_core.c
> index 3d241446099c..ccc6b5c1b24b 100644
> --- a/drivers/crypto/virtio/virtio_crypto_core.c
> +++ b/drivers/crypto/virtio/virtio_crypto_core.c
> @@ -75,15 +75,20 @@ static void virtcrypto_done_task(unsigned long data)
>         struct data_queue *data_vq = (struct data_queue *)data;
>         struct virtqueue *vq = data_vq->vq;
>         struct virtio_crypto_request *vc_req;
> +       unsigned long flags;
>         unsigned int len;
>
> +       spin_lock_irqsave(&data_vq->lock, flags);
>         do {
>                 virtqueue_disable_cb(vq);
>                 while ((vc_req = virtqueue_get_buf(vq, &len)) != NULL) {
> +                       spin_unlock_irqrestore(&data_vq->lock, flags);
>                         if (vc_req->alg_cb)
>                                 vc_req->alg_cb(vc_req, len);
> +                       spin_lock_irqsave(&data_vq->lock, flags);
>                 }
>         } while (!virtqueue_enable_cb(vq));
> +       spin_unlock_irqrestore(&data_vq->lock, flags);
>  }

Another thing that needs to care:

There seems to be a redundant virtqueue_kick() in
virtio_crypto_skcipher_crypt_req() which is out of the protection of
the spinlock.

I think we can simply remote that?

Thanks

>
>  static void virtcrypto_dataq_callback(struct virtqueue *vq)
> --
> 2.39.3
>