Subject: [PATCH v4 02/20] virtio: pci-legacy: Validate queue pfn

From: [email-masked] (Michael S. Tsirkin)
Date: Sun, 22 Jul 2018 18:53:59 +0300

On Wed, Jul 18, 2018 at 10:18:45AM +0100, Suzuki K Poulose wrote:
> Legacy PCI over virtio uses a 32bit PFN for the queue. If the
> queue pfn is too large to fit in 32bits, which we could hit on
> arm64 systems with 52bit physical addresses (even with 64K page
> size), we simply miss out a proper link to the other side of
> the queue.
> 
> Add a check to validate the PFN, rather than silently breaking
> the devices.
> 
> Cc: "Michael S. Tsirkin" <[email-masked]>
> Cc: Jason Wang <[email-masked]>
> Cc: Marc Zyngier <[email-masked]>
> Cc: Christoffer Dall <[email-masked]>
> Cc: Peter Maydel <[email-masked]>
> Cc: Jean-Philippe Brucker <[email-masked]>
> Signed-off-by: Suzuki K Poulose <[email-masked]>

Acked-by: Michael S. Tsirkin <[email-masked]>

I assume this will be merged through some other tree.

> ---
> Changes since v2:
>  - Change errno to -E2BIG
> ---
>  drivers/virtio/virtio_pci_legacy.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> index 2780886..de062fb 100644
> --- a/drivers/virtio/virtio_pci_legacy.c
> +++ b/drivers/virtio/virtio_pci_legacy.c
> @@ -122,6 +122,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
>  	struct virtqueue *vq;
>  	u16 num;
>  	int err;
> +	u64 q_pfn;
>  
>  	/* Select the queue we're interested in */
>  	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
> @@ -141,9 +142,17 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
>  	if (!vq)
>  		return ERR_PTR(-ENOMEM);
>  
> +	q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
> +	if (q_pfn >> 32) {
> +		dev_err(&vp_dev->pci_dev->dev,
> +			"platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
> +			0x1ULL << (32 + PAGE_SHIFT - 30));
> +		err = -E2BIG;
> +		goto out_del_vq;
> +	}
> +
>  	/* activate the queue */
> -	iowrite32(virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
> -		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> +	iowrite32(q_pfn, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
>  
>  	vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
>  
> @@ -160,6 +169,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
>  
>  out_deactivate:
>  	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> +out_del_vq:
>  	vring_del_virtqueue(vq);
>  	return ERR_PTR(err);
>  }
> -- 
> 2.7.4