linux-kernel - Re: [PATCH v3 2/6] vfio/type1: Check reserve region conflict and update iova list

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Date:   Fri, 16 Feb 2018 14:18:10 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
Cc:     <eric.auger@...hat.com>, <pmorel@...ux.vnet.ibm.com>,
        <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <john.garry@...wei.com>,
        <xuwei5@...ilicon.com>
Subject: Re: [PATCH v3 2/6] vfio/type1: Check reserve region conflict and
 update iova list

On Thu, 15 Feb 2018 09:45:00 +0000
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> wrote:

> This retrieves the reserved regions associated with dev group and
> checks for conflicts with any existing dma mappings. Also update
> the iova list excluding the reserved regions.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 86 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 85 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 4726f55..4db87a9 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1303,6 +1303,72 @@ static int vfio_iommu_aper_resize(struct list_head *iova,
>  	return 0;
>  }
>  
> +/*
> + * Check reserved region conflicts with existing dma mappings
> + */
> +static bool vfio_iommu_resv_conflict(struct vfio_iommu *iommu,
> +				struct list_head *resv_regions)
> +{
> +	struct iommu_resv_region *region;
> +
> +	/* Check for conflict with existing dma mappings */
> +	list_for_each_entry(region, resv_regions, list) {
> +		if (vfio_find_dma(iommu, region->start, region->length))
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +/*
> + * Check iova region overlap with  reserved regions and
> + * exclude them from the iommu iova range
> + */
> +static int vfio_iommu_resv_exclude(struct list_head *iova,
> +					struct list_head *resv_regions)
> +{
> +	struct iommu_resv_region *resv;
> +	struct vfio_iova *n, *next;
> +
> +	list_for_each_entry(resv, resv_regions, list) {
> +		phys_addr_t start, end;
> +
> +		start = resv->start;
> +		end = resv->start + resv->length - 1;
> +
> +		list_for_each_entry_safe(n, next, iova, list) {
> +			int ret = 0;
> +
> +			/* No overlap */
> +			if ((start > n->end) || (end < n->start))
> +				continue;
> +			/*
> +			 * Insert a new node if current node overlaps with the
> +			 * reserve region to exlude that from valid iova range.
> +			 * Note that, new node is inserted before the current
> +			 * node and finally the current node is deleted keeping
> +			 * the list updated and sorted.
> +			 */
> +			if (start > n->start)
> +				ret = vfio_insert_iova(n->start, start - 1,
> +								 &n->list);
> +			if (!ret && end < n->end)
> +				ret = vfio_insert_iova(end + 1, n->end,
> +							     &n->list);
> +			if (ret)
> +				return ret;
> +
> +			list_del(&n->list);
> +			kfree(n);
> +		}
> +	}
> +
> +	if (list_empty(iova))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>  static int vfio_iommu_get_iova_copy(struct vfio_iommu *iommu,
>  				struct list_head *iova_copy)
>  {
> @@ -1346,7 +1412,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	bool resv_msi, msi_remap;
>  	phys_addr_t resv_msi_base;
>  	struct iommu_domain_geometry geo;
> -	struct list_head iova_copy;
> +	struct list_head iova_copy, group_resv_regions;
> +	struct iommu_resv_region *resv, *resv_next;
>  	struct vfio_iova *iova, *iova_next;
>  
>  	mutex_lock(&iommu->lock);
> @@ -1426,6 +1493,14 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  		goto out_detach;
>  	}
>  
> +	INIT_LIST_HEAD(&group_resv_regions);

LIST_HEAD()

> +	iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
> +
> +	if (vfio_iommu_resv_conflict(iommu, &group_resv_regions)) {
> +		ret = -EINVAL;
> +		goto out_detach;
> +	}
> +
>  	/* Get a copy of the current iova list and work on it */
>  	INIT_LIST_HEAD(&iova_copy);
>  	ret = vfio_iommu_get_iova_copy(iommu, &iova_copy);
> @@ -1437,6 +1512,10 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	if (ret)
>  		goto out_detach;
>  
> +	ret = vfio_iommu_resv_exclude(&iova_copy, &group_resv_regions);
> +	if (ret)
> +		goto out_detach;
> +
>  	resv_msi = vfio_iommu_has_sw_msi(iommu_group, &resv_msi_base);
>  
>  	INIT_LIST_HEAD(&domain->group_list);
> @@ -1497,6 +1576,9 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	/* Delete the old one and insert new iova list */
>  	vfio_iommu_insert_iova_copy(iommu, &iova_copy);
>  
> +	list_for_each_entry_safe(resv, resv_next, &group_resv_regions, list)
> +		kfree(resv);

list_del() here and below, also this can be done after the mutex unlock.

> +
>  	mutex_unlock(&iommu->lock);
>  
>  	return 0;
> @@ -1507,6 +1589,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	iommu_domain_free(domain->domain);
>  	list_for_each_entry_safe(iova, iova_next, &iova_copy, list)
>  		kfree(iova);
> +	list_for_each_entry_safe(resv, resv_next, &group_resv_regions, list)
> +		kfree(resv);
>  out_free:
>  	kfree(domain);
>  	kfree(group);