Re: [Xen-devel] [PATCH v3 12/13] x86: add iommu_ops to modify and flush IOMMU mappings

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jul 17, 2018 at 02:38:15PM +0100, Paul Durrant wrote:
>  
[...]
> +static int iommuop_map(struct xen_iommu_op_map *op)
> +{
> +    struct domain *d, *currd = current->domain;
> +    struct domain_iommu *iommu = dom_iommu(currd);
> +    bool readonly = op->flags & XEN_IOMMUOP_map_readonly;
> +    bfn_t bfn = _bfn(op->bfn);
> +    struct page_info *page;
> +    unsigned int prot;
> +    int rc, ignore;
> +
> +    if ( op->pad || (op->flags & ~XEN_IOMMUOP_map_readonly) )
> +        return -EINVAL;
> +
> +    if ( !iommu->iommu_op_ranges )
> +        return -EOPNOTSUPP;
> +
> +    /* Check whether the specified BFN falls in a reserved region */
> +    if ( rangeset_contains_singleton(iommu->reserved_ranges, bfn_x(bfn)) )
> +        return -EINVAL;
> +
> +    d = rcu_lock_domain_by_any_id(op->domid);

I think this needs to be moved earlier before dereferencing assigning
iommu -- it depends on d being valid.

Same applies to the unmap function.

> +
> +static int iommuop_flush(void)
> +{
> +    return !iommu_iotlb_flush_all(current->domain) ? 0 : -EIO;

I don't follow: why does this only flush current->domain? But
map/unmap use explicit argument to specify a domain?

Wei.

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