Re: [Xen-devel] [PATCH v3 3/5] ARM: ITS: Deny hardware domain access to ITS

[Julien Grall <julien.grall@xxxxxxx>]

On 07/09/17 17:57, Andre Przywara wrote:
> Hi,
Hi,

> On 05/09/17 18:14, mjaggi@xxxxxxxxxxxxxxxxxx wrote:
> > From: Manish Jaggi <mjaggi@xxxxxxxxxx>
> >
> > This patch extends the gicv3_iomem_deny_access functionality by adding
> > support for ITS region as well. Add function gicv3_its_deny_access.
> >
> > Signed-off-by: Manish Jaggi <mjaggi@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/gic-v3-its.c        | 22 ++++++++++++++++++++++
> >   xen/arch/arm/gic-v3.c            |  3 +++
> >   xen/include/asm-arm/gic_v3_its.h |  9 +++++++++
> >   3 files changed, 34 insertions(+)
> >
> > diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
> > index 536b48d..0ab1466 100644
> > --- a/xen/arch/arm/gic-v3-its.c
> > +++ b/xen/arch/arm/gic-v3-its.c
> > @@ -20,6 +20,7 @@
> >   
> >   #include <xen/lib.h>
> >   #include <xen/delay.h>
> > +#include <xen/iocap.h>
> >   #include <xen/libfdt/libfdt.h>
> >   #include <xen/mm.h>
> >   #include <xen/rbtree.h>
> > @@ -906,6 +907,27 @@ struct pending_irq *gicv3_assign_guest_event(struct domain 
> > *d,
> >       return pirq;
> >   }
> >   
> > +int gicv3_its_deny_access(const struct domain *d)
> > +{
> > +    int rc = 0;
> > +    unsigned long mfn, nr;
> > +    const struct host_its *its_data;
> > +
> > +    list_for_each_entry( its_data, &host_its_list, entry )
> > +    {
> > +        mfn = paddr_to_pfn(its_data->addr);
> > +        nr = PFN_UP(ACPI_GICV3_ITS_MEM_SIZE);
> Shouldn't this not only cover the ITS register frame, but also the
> following 64K page containing the doorbell address? Otherwise we leave
> the doorbell address open, which seems to be asking for trouble ...
I think you are right. We don't want to allow the hardware domain to map 
the doorbell itself. This should only be done by Xen.
Cheers,

--
Julien Grall

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