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Subject: Re: [PATCH v7 5/6] vfio/type1: Add IOVA range capability support
To:     Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
        alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        iommu@lists.linux-foundation.org, linuxarm@huawei.com,
        john.garry@huawei.com, xuwei5@hisilicon.com, kevin.tian@intel.com
References: <20190626151248.11776-1-shameerali.kolothum.thodi@huawei.com>
 <20190626151248.11776-6-shameerali.kolothum.thodi@huawei.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <78727f63-e83f-f588-f0db-79ceb0dcbab9@redhat.com>
Date:   Sun, 7 Jul 2019 17:03:40 +0200
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Hi Shameer,

On 6/26/19 5:12 PM, Shameer Kolothum wrote:
> This allows the user-space to retrieve the supported IOVA
> range(s), excluding any reserved regions. The implementation
non relaxable reserved regions
> is based on capability chains, added to VFIO_IOMMU_GET_INFO ioctl.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> v6 --> v7
> 
> Addressed mdev case with empty iovas list(Suggested by Alex)
> ---
>  drivers/vfio/vfio_iommu_type1.c | 101 ++++++++++++++++++++++++++++++++
>  include/uapi/linux/vfio.h       |  23 ++++++++
>  2 files changed, 124 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 89ad0da7152c..450081802dcd 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -2141,6 +2141,73 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
>  	return ret;
>  }
>  
> +static int vfio_iommu_iova_add_cap(struct vfio_info_cap *caps,
> +		 struct vfio_iommu_type1_info_cap_iova_range *cap_iovas,
> +		 size_t size)
> +{
> +	struct vfio_info_cap_header *header;
> +	struct vfio_iommu_type1_info_cap_iova_range *iova_cap;
> +
> +	header = vfio_info_cap_add(caps, size,
> +				   VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE, 1);
> +	if (IS_ERR(header))
> +		return PTR_ERR(header);
> +
> +	iova_cap = container_of(header,
> +				struct vfio_iommu_type1_info_cap_iova_range,
> +				header);
> +	iova_cap->nr_iovas = cap_iovas->nr_iovas;
> +	memcpy(iova_cap->iova_ranges, cap_iovas->iova_ranges,
> +	       cap_iovas->nr_iovas * sizeof(*cap_iovas->iova_ranges));
> +	return 0;
> +}
> +
> +static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
> +				      struct vfio_info_cap *caps)
> +{
> +	struct vfio_iommu_type1_info_cap_iova_range *cap_iovas;
> +	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) {
> +		/*
> +		 * Return 0 as a container with only an mdev device
> +		 * will have an empty list
> +		 */
> +		ret = 0;
> +		goto out_unlock;
> +	}
> +
> +	size = sizeof(*cap_iovas) + (iovas * sizeof(*cap_iovas->iova_ranges));
> +
> +	cap_iovas = kzalloc(size, GFP_KERNEL);
> +	if (!cap_iovas) {
> +		ret = -ENOMEM;
> +		goto out_unlock;
> +	}
> +
> +	cap_iovas->nr_iovas = iovas;
> +
> +	list_for_each_entry(iova, &iommu->iova_list, list) {
> +		cap_iovas->iova_ranges[i].start = iova->start;
> +		cap_iovas->iova_ranges[i].end = iova->end;
> +		i++;
> +	}
> +
> +	ret = vfio_iommu_iova_add_cap(caps, cap_iovas, size);
> +
> +	kfree(cap_iovas);
> +out_unlock:
> +	mutex_unlock(&iommu->lock);
> +	return ret;
> +}
> +
>  static long vfio_iommu_type1_ioctl(void *iommu_data,
>  				   unsigned int cmd, unsigned long arg)
>  {
> @@ -2162,19 +2229,53 @@ 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 };
> +		unsigned long capsz;
> +		int ret;
>  
>  		minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
>  
> +		/* For backward compatibility, cannot require this */
> +		capsz = offsetofend(struct vfio_iommu_type1_info, cap_offset);
> +
>  		if (copy_from_user(&info, (void __user *)arg, minsz))
>  			return -EFAULT;
>  
>  		if (info.argsz < minsz)
>  			return -EINVAL;
>  
> +		if (info.argsz >= capsz) {
> +			minsz = capsz;
> +			info.cap_offset = 0; /* output, no-recopy necessary */
> +		}
> +
>  		info.flags = VFIO_IOMMU_INFO_PGSIZES;
>  
>  		info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
>  
> +		ret = vfio_iommu_iova_build_caps(iommu, &caps);
> +		if (ret)
> +			return ret;
> +
> +		if (caps.size) {
> +			info.flags |= VFIO_IOMMU_INFO_CAPS;
> +
> +			if (info.argsz < sizeof(info) + caps.size) {
> +				info.argsz = sizeof(info) + caps.size;
> +			} 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);
> +		}
> +
>  		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 8f10748dac79..1951d87115e8 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -714,7 +714,30 @@ 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 */
comment indent?
> +};
> +
> +/*
> + * The IOVA capability allows to report the valid IOVA range(s)
> + * excluding any reserved regions associated with dev group. Any dma
any non relaxable reserved regions exposed by devices attached to the
container?
s/dma/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_RANGE  1
> +
> +struct vfio_iova_range {
> +	__u64	start;
> +	__u64	end;
> +};
> +
> +struct vfio_iommu_type1_info_cap_iova_range {
> +	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)
> 
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric