Re: [RFC v2 4/5] vfio/type1: Add IOVA range capability support

[Auger Eric]

Hi Shameer,

On 12/01/18 17:45, Shameer Kolothum wrote:
> This  allows the user-space to retrieve the supported IOVA
> range(s), excluding any reserved regions. The implementation
> is based on capability chains, added to VFIO_IOMMU_GET_INFO ioctl.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 91 +++++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/vfio.h       | 23 +++++++++++
>  2 files changed, 114 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 47ea490..dc6ed85 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1893,6 +1893,67 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
>  	return ret;
>  }
>  
> +static int vfio_add_iova_cap(struct vfio_info_cap *caps, void *cap_type,
can't you pass cap_type directly as a struct vfio_iommu_type1_info_cap_iova?

Also maybe using more explicit name for cap_type such as cap_iova_ranges?
> +			     size_t size)
> +{
> +	struct vfio_info_cap_header *header;
> +	struct vfio_iommu_type1_info_cap_iova *iova_cap, *iova = cap_type;
> +
> +	header = vfio_info_cap_add(caps, size,
> +				VFIO_IOMMU_TYPE1_INFO_CAP_IOVA, 1);
> +	if (IS_ERR(header))
> +		return PTR_ERR(header);
> +
> +	iova_cap = container_of(header,
> +			struct vfio_iommu_type1_info_cap_iova, header);
> +	iova_cap->nr_iovas = iova->nr_iovas;
> +	memcpy(iova_cap->iova_ranges, iova->iova_ranges,
> +			iova->nr_iovas * sizeof(*iova->iova_ranges));
> +	return 0;
> +}
> +
> +static int vfio_build_iommu_iova_caps(struct vfio_iommu *iommu,
> +				struct vfio_info_cap *caps)
> +{
> +	struct vfio_iommu_type1_info_cap_iova *iova_cap;
> +	struct vfio_iova *iova;
> +	size_t size;
> +	int iovas = 0, i = 0, ret;
> +
> +	mutex_lock(&iommu->lock);
> +
> +	list_for_each_entry(iova, &iommu->iova_list, list)
> +		iovas++;
> +
> +	if (!iovas) {
> +		ret = EINVAL;
> +		goto out_unlock;
> +	}
> +
> +	size = sizeof(*iova_cap) + (iovas * sizeof(*iova_cap->iova_ranges));
> +
> +	iova_cap = kzalloc(size, GFP_KERNEL);
> +	if (!iova_cap) {
> +		ret = -ENOMEM;
> +		goto out_unlock;
> +	}
> +
> +	iova_cap->nr_iovas = iovas;
> +
> +	list_for_each_entry(iova, &iommu->iova_list, list) {
> +		iova_cap->iova_ranges[i].start = iova->start;
> +		iova_cap->iova_ranges[i].end = iova->end;
> +		i++;
> +	}
> +
> +	ret = vfio_add_iova_cap(caps, iova_cap, size);
> +
> +	kfree(iova_cap);
> +out_unlock:
> +	mutex_unlock(&iommu->lock);
> +	return ret;
> +}
> +
>  static long vfio_iommu_type1_ioctl(void *iommu_data,
>  				   unsigned int cmd, unsigned long arg)
>  {
> @@ -1914,6 +1975,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  		}
>  	} else if (cmd == VFIO_IOMMU_GET_INFO) {
>  		struct vfio_iommu_type1_info info;
> +		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
> +		int ret;
>  
>  		minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
>  
> @@ -1927,6 +1990,34 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  
>  		info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
>  
> +		if (info.argsz == minsz)
> +			goto done;
> +
> +		ret = vfio_build_iommu_iova_caps(iommu, &caps);
> +		if (ret)
> +			return ret;
> +
> +		if (caps.size) {
> +			info.flags |= VFIO_IOMMU_INFO_CAPS;
> +			minsz = offsetofend(struct vfio_iommu_type1_info,
> +							 cap_offset);
> +			if (info.argsz < sizeof(info) + caps.size) {
> +				info.argsz = sizeof(info) + caps.size;
> +				info.cap_offset = 0;
> +			} else {
> +				vfio_info_cap_shift(&caps, sizeof(info));
> +				if (copy_to_user((void __user *)arg +
> +						sizeof(info), caps.buf,
> +						caps.size)) {
> +					kfree(caps.buf);
> +					return -EFAULT;
> +				}
> +				info.cap_offset = sizeof(info);
> +			}
> +
> +			kfree(caps.buf);
> +		}
> +done:
>  		return copy_to_user((void __user *)arg, &info, minsz) ?
>  			-EFAULT : 0;
>  
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index e3301db..8671448 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -517,7 +517,30 @@ struct vfio_iommu_type1_info {
>  	__u32	argsz;
>  	__u32	flags;
>  #define VFIO_IOMMU_INFO_PGSIZES (1 << 0)	/* supported page sizes info */
> +#define VFIO_IOMMU_INFO_CAPS	(1 << 1)	/* Info supports caps */
>  	__u64	iova_pgsizes;		/* Bitmap of supported page sizes */
> +	__u32   cap_offset;	/* Offset within info struct of first cap */
> +};
> +
> +/*
> + * The IOVA capability allows to report the valid IOVA range(s)
> + * excluding any reserved regions associated with dev group. Any dma
> + * map attempt outside the valid iova range will return error.
> + *
> + * The structures below define version 1 of this capability.
> + */
> +#define VFIO_IOMMU_TYPE1_INFO_CAP_IOVA  1
VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE ?
> +
> +struct vfio_iova_range {
> +	__u64	start;
> +	__u64	end;
> +};
> +
> +struct vfio_iommu_type1_info_cap_iova {
cap_iova_ranges?
> +	struct vfio_info_cap_header header;
> +	__u32	nr_iovas;
> +	__u32	reserved;
> +	struct vfio_iova_range iova_ranges[];
>  };
>  
>  #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
> 
Otherwise looks good to me.

Thanks

Eric