RE: [Xen-devel] [PATCH] x86/xen: allow userspace access during hypercalls

[Paul Durrant]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
> Marek Marczykowski-GÃrecki
> Sent: 26 June 2017 13:45
> To: Juergen Groà <jgross@xxxxxxxx>
> Cc: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; x86@xxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; xen-
> devel@xxxxxxxxxxxxxxxxxxxx; Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Subject: Re: [Xen-devel] [PATCH] x86/xen: allow userspace access during
> hypercalls
> 
> On Mon, Jun 26, 2017 at 02:05:48PM +0200, Juergen Groà wrote:
> > On 06/23/2017 02:47 PM, Marek Marczykowski-GÃrecki wrote:
> > > Userspace application can do a hypercall through /dev/xen/privcmd, and
> > > some for some hypercalls argument is a pointers to user-provided
> > > structure. When SMAP is supported and enabled, hypervisor can't access.
> > > So, lets allow it.
> >
> > What about HYPERVISOR_dm_op?
> 
> Indeed, arguments copied to kernel space there are only addresses of
> buffers. Will send v2 in a moment.
> But I can't test it right now, as for my understanding this require
> HVM/PVHv2 dom0 or stubdomain...
> 

No, you don't need anything particularly special to use dm_op. Just up-to-date xen, privcmd, and QEMU. QEMU should end up using dm_op by default if all three are in place.

  Paul

> --
> Best Regards,
> Marek Marczykowski-GÃrecki
> Invisible Things Lab
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