Re: [PATCH v2 1/8] public / x86: Introduce __HYPERCALL_dm_op...

[Paul Durrant <Paul.Durrant@citrix.com>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: 15 December 2016 15:23
> To: Paul Durrant <Paul.Durrant@citrix.com>
> Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>; Ian Jackson
> <Ian.Jackson@citrix.com>; Jennifer Herbert <jennifer.herbert@citrix.com>;
> Wei Liu <wei.liu2@citrix.com>; xen-devel@lists.xenproject.org; Daniel De
> Graaf <dgdegra@tycho.nsa.gov>
> Subject: Re: [PATCH v2 1/8] public / x86: Introduce __HYPERCALL_dm_op...
> 
> >>> On 06.12.16 at 14:46, <paul.durrant@citrix.com> wrote:
> > ...as a set of hypercalls to be used by a device model.
> >
> > As stated in the new docs/designs/dm_op.markdown:
> >
> > "The aim of DMOP is to prevent a compromised device model from
> > compromising domains other then the one it is associated with. (And is
> > therefore likely already compromised)."
> >
> > See that file for further information.
> >
> > This patch simply adds the boilerplate for the hypercall.
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> > Suggested-by: Ian Jackson <ian.jackson@citrix.com>
> > Suggested-by: Jennifer Herbert <jennifer.herbert@citrix.com>
> 
> Hypervisor parts
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> albeit with one more question/adjustment request:
> 
> > +struct xen_dm_op_buf {
> > +    XEN_GUEST_HANDLE(void) h;
> > +    uint64_aligned_t size;
> 
> Does size need to be 64 bits wide? I thing 32 should suffice, even if
> that won't shrink structure size (because the handle really wants to
> be XEN_GUEST_HANDLE_64() for a tool stack-only interface which
> we don't want to have a compat wrapper for).

Sure. I don't think it does need to be that wide in reality.

  Paul

> 
> Jan


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