Re: [Xen-devel] [PATCH] amd iommu: disable iommu emulation on non-iommu systems

[Wei Wang <wei.wang2@xxxxxxx>]

On 02/01/2012 04:58 PM, Jan Beulich wrote:
> > > > On 26.01.12 at 11:56, Wei Wang<wei.wang2@xxxxxxx>  wrote:
> > --- a/xen/drivers/passthrough/amd/iommu_guest.c Tue Jan 24 16:46:17 2012 +0000
> > +++ b/xen/drivers/passthrough/amd/iommu_guest.c Thu Jan 26 11:50:02 2012 +0100
> > @@ -805,6 +805,9 @@ int guest_iommu_set_base(struct domain *
> >      p2m_type_t t;
> >      struct guest_iommu *iommu = domain_iommu(d);
> >
> > +    if ( !is_hvm_domain(d) || !iommu_enabled || !iommuv2_enabled )
> > +        return 0;
> Is it really appropriate/correct to return 0 here, while ...

good point, will be fixed in the next try. No one use 
guest_iommu_set_base so far until remaining patches got committed.
> > +
> >      if ( !iommu )
> >          return -EACCES;
> ... here it is -EACCES? Further, are the extra checks needed at all
> (i.e. wouldn't domain_iommu() return NULL in all of these cases
> anyway due to the same checks being added to guest_iommu_init())?
> If so, the checks you add to guest_iommu_destroy() are pointless
> too.
It is just to make sure those functions are not called by an unexpected 
code path since it is non-static. But I can remove it if you prefer that.

Thanks,
Wei

> Jan


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