Re: [PATCH v1 01/16] virtio: Validate queue pfn for 32bit transports

[Michael S. Tsirkin]

On Tue, Jan 09, 2018 at 07:03:56PM +0000, Suzuki K Poulose wrote:
> virtio-mmio using virtio-v1 and virtio legacy pci use 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" <mst@xxxxxxxxxx>
> Cc: Jason Wang <jasowang@xxxxxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: Christoffer Dall <cdall@xxxxxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>

Could you guys please work on virtio 1 support in
for virtio mmio in qemu though?
It's not a lot of code.

> ---
>  drivers/virtio/virtio_mmio.c       | 19 ++++++++++++++++---
>  drivers/virtio/virtio_pci_legacy.c | 11 +++++++++--
>  2 files changed, 25 insertions(+), 5 deletions(-)

I'd rather see this as 2 patches.

> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index a9192fe4f345..47109baf37f7 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -358,6 +358,7 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
>  	struct virtqueue *vq;
>  	unsigned long flags;
>  	unsigned int num;
> +	u64 addr;
>  	int err;
>  
>  	if (!name)
> @@ -394,16 +395,26 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
>  		goto error_new_virtqueue;
>  	}
>  
> +	addr = virtqueue_get_desc_addr(vq);
> +	/*
> +	 * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something that
> +	 * doesn't fit in 32bit, fail the setup rather than pretending to
> +	 * be successful.
> +	 */
> +	if (vm_dev->version == 1 && (addr >> (PAGE_SHIFT + 32))) {
> +		dev_err(&vdev->dev, "virtio-mmio: queue address too large\n");
> +		err = -ENOMEM;
> +		goto error_bad_pfn;
> +	}
> +

Can you please move this below to where it's actually used?

>  	/* Activate the queue */
>  	writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
>  	if (vm_dev->version == 1) {
>  		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> -		writel(virtqueue_get_desc_addr(vq) >> PAGE_SHIFT,
> +		writel(addr >> PAGE_SHIFT,
>  				vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
>  	} else {
> -		u64 addr;
>  
> -		addr = virtqueue_get_desc_addr(vq);
>  		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
>  		writel((u32)(addr >> 32),
>  				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
> @@ -430,6 +441,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
>  
>  	return vq;
>  
> +error_bad_pfn:
> +	vring_del_virtqueue(vq);
>  error_new_virtqueue:
>  	if (vm_dev->version == 1) {
>  		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> index 2780886e8ba3..099d2cfb47b3 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 +142,15 @@ 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, "virtio-pci queue PFN too large\n");
> +		err = -ENOMEM;
> +		goto out_deactivate;

You never set up the address, it's cleaner to add another target
and not reset it.

> +	}
> +
>  	/* activate the queue */
> -	iowrite32(virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
> -		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> +	iowrite32((u32)q_pfn, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
>  
>  	vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
>  
> -- 
> 2.13.6