linux-kernel - Re: [PATCH] um: virt-pci: set device ready in probe()

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Date:   Fri, 10 Jun 2022 20:34:04 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Johannes Berg <johannes@...solutions.net>, kernel@...s.com,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
        Jason Wang <jasowang@...hat.com>, linux-um@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] um: virt-pci: set device ready in probe()

On Fri, Jun 10, 2022 at 05:12:03PM +0200, Vincent Whitchurch wrote:
> Call virtio_device_ready() to make this driver work after commit
> b4ec69d7e09 ("virtio: harden vring IRQ"), since the driver uses the
> virtqueues in the probe function.  (The virtio core sets the device
> ready when probe returns.)
> 
> Fixes: 8b4ec69d7e09 ("virtio: harden vring IRQ")
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>

Also fixes this commit:

commit 68f5d3f3b6543266b29e047cfaf9842333019b4c
Author: Johannes Berg <johannes.berg@...el.com>
Date:   Fri Mar 5 13:19:58 2021 +0100

    um: add PCI over virtio emulation driver
    

BTW Johannes I think you need to spec this device and get
an ID - what's the plan for that? Current hack of punting
this to userspace isn't really any good long term.


> ---
>  arch/um/drivers/virt-pci.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/um/drivers/virt-pci.c b/arch/um/drivers/virt-pci.c
> index 5c092a9153ea..027847023184 100644
> --- a/arch/um/drivers/virt-pci.c
> +++ b/arch/um/drivers/virt-pci.c
> @@ -544,6 +544,8 @@ static int um_pci_init_vqs(struct um_pci_device *dev)
>  	dev->cmd_vq = vqs[0];
>  	dev->irq_vq = vqs[1];
>  
> +	virtio_device_ready(dev->vdev);
> +
>  	for (i = 0; i < NUM_IRQ_MSGS; i++) {
>  		void *msg = kzalloc(MAX_IRQ_MSG_SIZE, GFP_KERNEL);
>  
> @@ -587,7 +589,7 @@ static int um_pci_virtio_probe(struct virtio_device *vdev)
>  	dev->irq = irq_alloc_desc(numa_node_id());
>  	if (dev->irq < 0) {
>  		err = dev->irq;
> -		goto error;
> +		goto err_reset;
>  	}
>  	um_pci_devices[free].dev = dev;
>  	vdev->priv = dev;
> @@ -604,6 +606,9 @@ static int um_pci_virtio_probe(struct virtio_device *vdev)
>  
>  	um_pci_rescan();
>  	return 0;
> +err_reset:
> +	virtio_reset_device(vdev);
> +	vdev->config->del_vqs(vdev);
>  error:
>  	mutex_unlock(&um_pci_mtx);
>  	kfree(dev);
> -- 
> 2.34.1