Re: [RFC PATCH 6/8] VFIO: do pasid table binding

[Xiao Guangrong <guangrong.xiao@gmail.com>]

On 04/26/2017 06:12 PM, Liu, Yi L wrote:
> From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
> 
> This patch adds IOCTL processing in vfio_iommu_type1 for
> VFIO_IOMMU_SVM_BIND_TASK. Binds the PASID table bind by
> calling iommu_ops->bind_pasid_table to link the whole
> PASID table to pIOMMU.
> 
> For VT-d, it is linking the guest PASID table to host pIOMMU.
> This is key point to support SVM virtualization on VT-d.
> 
> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> ---
>   drivers/vfio/vfio_iommu_type1.c | 72 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 72 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index b3cc33f..30b6d48 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1512,6 +1512,50 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
>   	return ret;
>   }
>   
> +struct vfio_svm_task {
> +	struct iommu_domain *domain;
> +	void *payload;
> +};
> +
> +static int bind_pasid_tbl_fn(struct device *dev, void *data)
> +{
> +	int ret = 0;
> +	struct vfio_svm_task *task = data;
> +	struct pasid_table_info *pasidt_binfo;
> +
> +	pasidt_binfo = task->payload;
> +	ret = iommu_bind_pasid_table(task->domain, dev, pasidt_binfo);
> +	return ret;
> +}
> +
> +static int vfio_do_svm_task(struct vfio_iommu *iommu, void *data,
> +				int (*fn)(struct device *, void *))
> +{
> +	int ret = 0;
> +	struct vfio_domain *d;
> +	struct vfio_group *g;
> +	struct vfio_svm_task task;
> +
> +	task.payload = data;
> +
> +	mutex_lock(&iommu->lock);
> +
> +	list_for_each_entry(d, &iommu->domain_list, next) {
> +		list_for_each_entry(g, &d->group_list, next) {
> +			if (g->iommu_group != NULL) {
> +				task.domain = d->domain;
> +				ret = iommu_group_for_each_dev(
> +					g->iommu_group, &task, fn);
> +				if (ret != 0)
> +					break;
> +			}
> +		}
> +	}
> +
> +	mutex_unlock(&iommu->lock);
> +	return ret;
> +}
> +
>   static long vfio_iommu_type1_ioctl(void *iommu_data,
>   				   unsigned int cmd, unsigned long arg)
>   {
> @@ -1582,6 +1626,34 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>   
>   		return copy_to_user((void __user *)arg, &unmap, minsz) ?
>   			-EFAULT : 0;
> +	} else if (cmd == VFIO_IOMMU_SVM_BIND_TASK) {
> +		struct vfio_device_svm hdr;
> +		u8 *data = NULL;
> +		int ret = 0;
> +
> +		minsz = offsetofend(struct vfio_device_svm, length);
> +		if (copy_from_user(&hdr, (void __user *)arg, minsz))
> +			return -EFAULT;
> +
> +		if (hdr.length == 0)
> +			return -EINVAL;
> +
> +		data = memdup_user((void __user *)(arg + minsz),
> +					hdr.length);

You should check the @length is at least sizeof(struct pasid_table_info) as
kernel uses it as pasid_table_info, a evil application can crash kernel.