Re: [Qemu-devel] [RFC 2/3] memory: add MemTxAttrs to IOMMUTLBEntry

[Peter Maydell]

On 5 June 2018 at 14:19, Peter Xu <address@hidden> wrote:
> It should never be used for translate() calls since the caller should be
> the one who passes in the MemTxAttrs.  However it could be used when we
> want to generate an IOMMU translation notification with specific
> translation attributes.
>
> Signed-off-by: Peter Xu <address@hidden>
> ---
>  include/exec/memory.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 6b0ced554d..12865a4890 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -72,6 +72,13 @@ struct IOMMUTLBEntry {
>      hwaddr           translated_addr;
>      hwaddr           addr_mask;  /* 0xfff = 4k translation */
>      IOMMUAccessFlags perm;
> +    /*
> +     * Attributes that were bound to the DMA translation.  Note that
> +     * this field is meaningless when the IOMMUTLBENtry is generated
> +     * by a translate() call.  It can be used as a hint when we want
> +     * to send IOMMU notifications with specific permission flags.
> +     */
> +    MemTxAttrs       attrs;
>  };

How do we say "this applies for more than just this set of
tx attrs" ? eg, if my IOMMU cares only about the secure/nonsecure
attribute, how do I express "this IOMMU TLB entry is valid for
both attrs.user = 1 and attrs.user = 0" ?

thanks
-- PMM