Re: [Xen-devel] IOREQ server on Arm

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.09.18 at 13:02, <Paul.Durrant@xxxxxxxxxx> wrote:
> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -1105,8 +1105,11 @@ static int acquire_resource(
> 
>          for ( i = 0; !rc && i < xmar.nr_frames; i++ )
>          {
> -            rc = set_foreign_p2m_entry(currd, gfn_list[i],
> -                                       _mfn(mfn_list[i]));
> +            rc = (xmar.flags & XENMEM_rsrc_acq_caller_owned) ?
> +                guest_physmap_add_entry(currd, gfn_list[i],
> +                                        _mfn(mfn_list[i]), 0, p2m_ram_rw) :
> +                set_foreign_p2m_entry(currd, gfn_list[i],
> +                                      _mfn(mfn_list[i]));
>              /* rc should be -EIO for any iteration other than the first */
>              if ( rc && i )
>                  rc = -EIO;
> 
> But the guest_physmap_add_entry() is problematic as it will IOMMU map pages 
> as well, which is probably not wanted.

Yeah, I'd prefer if we avoided establishing IOMMU mappings here.
How about transforming set_foreign_p2m_entry() into
set_special_p2m_entry(), with a type passed in?

Jan



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