Re: [Xen-devel] [PATCH 2/2] xen/arm: domain_build: Don't expose IOMMU specific properties to the guest

[Oleksandr <olekstysh@xxxxxxxxx>]

On 08.10.19 00:02, Julien Grall wrote:
> Hi,
Hi Julien


> > > But, this is clearly what happen in current Xen setup if the driver is
> > > not enabled. What I want to avoid is exposing an half complete
> > > bindings to the guest (you don't know how it will behave).
> > >
> > > So we either remove all the properties and node related to the IOMMUs
> > > or nothing.
> > I think, I got it. Our target is *not* to add a way for Dom0 to use
> > IOMMU, but to be consistent in removing IOMMU node/master device
> > properties. Now, we remove the IOMMU node if Xen identifies it (the
> > IOMMU driver is present in Xen),
> > so looks like we have to remove master device properties only if this
> > master device is behind the IOMMU which node is removed. This, I hope,
> > will avoid exposing an half complete bindings to guest. Am I right?
> >
> >
> > [1]
> > https://lists.xenproject.org/archives/html/xen-devel/2019-08/msg00858.html
> >
> >
> > ----------
> >
> > If you happy with that logic I will craft a proper patch.
> The logic looks alright to me. One comment below, I will look at the
> rest once this is formally sent.
ok


> > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > index 67021d9..6d45e55 100644
> > --- a/xen/arch/arm/domain_build.c
> > +++ b/xen/arch/arm/domain_build.c
> > @@ -480,10 +480,26 @@ static int __init write_properties(struct domain
> > *d, struct kernel_info *kinfo,
> >        const struct dt_property *prop, *status = NULL;
> >        int res = 0;
> >        int had_dom0_bootargs = 0;
> > +    struct dt_device_node *iommu_node;
> >
> >        if ( kinfo->cmdline && kinfo->cmdline[0] )
> >            bootargs = &kinfo->cmdline[0];
> >
> > +    /*
> > +     * If we skip the IOMMU device when creating DT for Dom0 (even if
> I would prefer if we use "hwdom" over "Dom0". They are both the same on
> Arm, but this may change in the future (we may actually drop Dom0 ;)).
Already sent v2, please see:

https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg00673.html

--
Regards,

Oleksandr Tyshchenko


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