Re: [Qemu-devel] [PATCH V3 05/10] intel_iommu: support device iotlb descriptor

[Michael S. Tsirkin]

On Tue, Nov 08, 2016 at 02:54:19PM +0800, Jason Wang wrote:
> 
> 
> On 2016年11月08日 07:35, Peter Xu wrote:
> > On Mon, Nov 07, 2016 at 03:09:50PM +0800, Jason Wang wrote:
> > 
> > [...]
> > 
> > > +static bool vtd_process_device_iotlb_desc(IntelIOMMUState *s,
> > > +                                          VTDInvDesc *inv_desc)
> > > +{
> > > +    VTDAddressSpace *vtd_dev_as;
> > > +    IOMMUTLBEntry entry;
> > Since "entry" is allocated on the stack...
> > 
> > [...]
> > 
> > > +    entry.target_as = &vtd_dev_as->as;
> > > +    entry.addr_mask = sz - 1;
> > > +    entry.iova = addr;
> > > +    memory_region_notify_iommu(entry.target_as->root, entry);
> > ... here we need to assign entry.perm explicitly to IOMMU_NONE, right?
> > 
> > Also I think it'll be nice that we set all the fields even not used,
> > to avoid rubbish from the stack passed down to notifier handlers.
> > 
> > [...]
> 
> This is better, if no other comments on the series I will post a patch on
> top to fix this.

If you do, pls remember to use the fixup! prefix.

> > 
> > > +static bool x86_iommu_device_iotlb_prop_get(Object *o, Error **errp)
> > > +{
> > > +    X86IOMMUState *s = X86_IOMMU_DEVICE(o);
> > > +    return s->dt_supported;
> > > +}
> > > +
> > > +static void x86_iommu_device_iotlb_prop_set(Object *o, bool value, Error 
> > > **errp)
> > > +{
> > > +    X86IOMMUState *s = X86_IOMMU_DEVICE(o);
> > > +    s->dt_supported = value;
> > > +}
> > > +
> > >   static void x86_iommu_instance_init(Object *o)
> > >   {
> > >       X86IOMMUState *s = X86_IOMMU_DEVICE(o);
> > > @@ -114,6 +126,11 @@ static void x86_iommu_instance_init(Object *o)
> > >       s->intr_supported = false;
> > >       object_property_add_bool(o, "intremap", x86_iommu_intremap_prop_get,
> > >                                x86_iommu_intremap_prop_set, NULL);
> > > +    s->dt_supported = false;
> > > +    object_property_add_bool(o, "device-iotlb",
> > > +                             x86_iommu_device_iotlb_prop_get,
> > > +                             x86_iommu_device_iotlb_prop_set,
> > > +                             NULL);
> > Again, a nit-pick here is to use Property for "device-iotlb":
> > 
> >      static Property vtd_properties[] = {
> >          DEFINE_PROP_UINT32("device-iotlb", X86IOMMUState, dt_supported, 
> > false),
> >          DEFINE_PROP_END_OF_LIST(),
> >      };
> > 
> > However not worth a repost.
> > 
> > Thanks,
> > 
> > -- peterx
> > 
> 
> We may want to share this with AMD IOMMU. (Looking at AMD IOMMU codes, its
> device-iotlb support is buggy).
> 
> Thanks