Re: [PATCH v3 08/13] x86: add iommu_op to query reserved ranges

[Wei Liu <wei.liu2@citrix.com>]

On Tue, Jul 17, 2018 at 02:38:11PM +0100, Paul Durrant wrote:
[...]
>  int compat_one_iommu_op(compat_iommu_op_buf_t *buf)
>  {
> -    compat_iommu_op_t cmp;
> +    compat_iommu_op_t cmp = {};
> +    size_t offset;
> +    static const size_t op_size[] = {
> +        [XEN_IOMMUOP_query_reserved] = sizeof(struct compat_iommu_op_query_reserved),
> +    };
> +    size_t size;
>      xen_iommu_op_t nat;
> +    unsigned int u;
> +    int32_t status;
>      int rc;
>  
> -    if ( buf->size < sizeof(cmp) )
> +    offset = offsetof(struct compat_iommu_op, u);
> +
> +    if ( buf->size < offset )
>          return -EFAULT;
>  
> -    if ( copy_from_compat((void *)&cmp, buf->h, sizeof(cmp)) )
> +    if ( copy_from_compat((void *)&cmp, buf->h, offset) )
>          return -EFAULT;
>  
>      if ( cmp.pad )
> @@ -119,12 +204,85 @@ int compat_one_iommu_op(compat_iommu_op_buf_t *buf)
>      if ( rc )
>          return rc;
>  
> +    if ( cmp.op >= ARRAY_SIZE(op_size) )
> +        return -EOPNOTSUPP;
> +
> +    size = op_size[array_index_nospec(cmp.op, ARRAY_SIZE(op_size))];
> +    if ( buf->size < offset + size )
> +        return -EFAULT;
> +
> +    if ( copy_from_compat_offset((void *)&cmp.u, buf->h, offset, size) )
> +        return -EFAULT;
> +
> +    /*
> +     * The xlat magic doesn't quite know how to handle the union so
> +     * we need to fix things up here.
> +     */
> +#define XLAT_iommu_op_u_query_reserved XEN_IOMMUOP_query_reserved

Missing undef for this.

[...]
> diff --git a/xen/include/public/iommu_op.h b/xen/include/public/iommu_op.h
> index c3b68f665a..02213c12a4 100644
> --- a/xen/include/public/iommu_op.h
> +++ b/xen/include/public/iommu_op.h
> @@ -25,11 +25,50 @@
>  
>  #include "xen.h"
>  
> +typedef unsigned long xen_bfn_t;
> +

This means xen_bfn_t will have different size on 32 bit and 64 bit
platform.

And obviously other unsigned ints in this commit and xen_pfn_t in later
patches will indeed make compat entry point necessary.

Wei.

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