Re: [Xen-devel] [PATCH v1 10/10] xen/arm: domain_build: Don't expose the "iommus" property to the guest

[Julien Grall <julien.grall@xxxxxxx>]

On 11/05/17 15:15, Oleksandr Tyshchenko wrote:
> On Thu, May 11, 2017 at 2:58 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> > Hi Oleksandr,
> Hi Julien
Hi,

> > On 10/05/17 15:03, Oleksandr Tyshchenko wrote:
> > > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > >
> > > We don't passthrough IOMMU device to DOM0 even if it is not used by
> > > Xen. Therefore exposing the property that describes the IOMMU
> > > master interfaces of the device does not make any sense.
> > >
> > > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > > ---
> > >  xen/arch/arm/domain_build.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > > index 3abacc0..2defb60 100644
> > > --- a/xen/arch/arm/domain_build.c
> > > +++ b/xen/arch/arm/domain_build.c
> > > @@ -432,6 +432,10 @@ static int write_properties(struct domain *d, struct
> > > kernel_info *kinfo,
> > >              continue;
> > >          }
> > >
> > > +        /* Don't expose the property "iommus" to the guest */
> > > +        if ( dt_property_name_is_equal(prop, "iommus") )
> > > +            continue;
> >
> > It would be useful to have a link to the bindings associated
> > (Documentation/devicetree/bindings/iommu/iommu.txt).
> Agree. I will mention it in commit description.
>
> > Also, whilst you are at it, you likely want to remove all the other iommu
> > properties such as iommu-map.
> Excuse me, I have never heard about it. Is it a required property?
This property is used to translate an RID into a Master ID (see the 
documentation in bindings/pci/pci-iommu.txt).
Cheers,

--
Julien Grall

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