linux-kernel - Re: [PATCH V2 1/5] virtio: use virtio_device_ready() in virtio_device

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Message-ID: <20220406073803-mutt-send-email-mst@kernel.org>
Date:   Wed, 6 Apr 2022 07:44:20 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, maz@...nel.org, tglx@...utronix.de,
        peterz@...radead.org, sgarzare@...hat.com,
        "Paul E. McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH V2 1/5] virtio: use virtio_device_ready() in
 virtio_device_restore()

patch had wrong mime type. I managed to extra it but pls fix.

> 
> 
> From: Stefano Garzarella <sgarzare@...hat.com>
> 
> It will allows us

will allow us

> to do extension on virtio_device_ready() without
> duplicating codes.

code

> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: "Paul E. McKenney" <paulmck@...nel.org>
> Cc: Marc Zyngier <maz@...nel.org>
> Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
> Signed-off-by: Jason Wang <jasowang@...hat.com>
> ---
>  drivers/virtio/virtio.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 22f15f444f75..75c8d560bbd3 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -526,8 +526,9 @@ int virtio_device_restore(struct virtio_device *dev)
>  			goto err;
>  	}
>  
> -	/* Finally, tell the device we're all set */
> -	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
> +	/* If restore didn't do it, mark device DRIVER_OK ourselves. */
> +	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
> +		virtio_device_ready(dev);
>  
>  	virtio_config_enable(dev);

it's unfortunate that this adds an extra vmexit since virtio_device_ready
calls get_status too.

We now have:

static inline
void virtio_device_ready(struct virtio_device *dev)
{
        unsigned status = dev->config->get_status(dev);
                
        BUG_ON(status & VIRTIO_CONFIG_S_DRIVER_OK);
        dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
}


I propose adding a helper and putting common code there.

>  
> -- 
> 2.25.1