Re: [Xen-devel] [PATCH 07 of 16] amd iommu: Add 2 hypercalls for libxc

[Wei Wang2 <wei.wang2@xxxxxxx>]

On Wednesday 14 December 2011 18:03:54 Jan Beulich wrote:
> >>> On 14.12.11 at 17:57, Wei Wang2 <wei.wang2@xxxxxxx> wrote:
> >
> > On Wednesday 14 December 2011 17:44:18 Jan Beulich wrote:
> >> >>> On 14.12.11 at 16:29, Wei Wang <wei.wang2@xxxxxxx> wrote:
> >> >
> >> > # HG changeset patch
> >> > # User Wei Wang <wei.wang2@xxxxxxx>
> >> > # Date 1323875772 -3600
> >> > # Node ID ef5698887d044ad58293bee3549eaa20310c2b17
> >> > # Parent  fbed4e6011fce13d3a521bbc339f4959bf32a06c
> >> > amd iommu: Add 2 hypercalls for libxc
> >> >
> >> > iommu_set_msi: used by qemu to inform hypervisor iommu vector number
> >> > in guest
> >> > space. Hypervisor needs this vector to inject msi into guest when PPR
> >> > logging
> >> > happens.
> >>
> >> And this cannot be done with the existing MSI emulation?
> >
> > It looks like MSI emulation are used for passthru devices. I only add
> > virtual amd iommu device and do not passthru amd iommu device. So no
> > physcal msi are required and therefore complicate msi emulation might not
> > be very necessary?
>
> Makes sense.
>
> >> > --- a/xen/include/public/domctl.h        Wed Dec 14 16:16:11 2011 +0100
> >> > +++ b/xen/include/public/domctl.h        Wed Dec 14 16:16:12 2011 +0100
> >> > @@ -848,6 +848,31 @@ struct xen_domctl_set_access_required {
> >> >  typedef struct xen_domctl_set_access_required
> >> > xen_domctl_set_access_required_t;
> >> >  DEFINE_XEN_GUEST_HANDLE(xen_domctl_set_access_required_t);
> >> >
> >> > +#if defined(__i386__) || defined(__x86_64__)
> >>
> >> What is x86-specific about these?
> >
> > These hypercalls are only used by AMD. so ia64 should be avoided
>
> Currently. But is there anything in them that makes them unusable
> for other IOMMUs in the future (from what I can tell only PCI and MSI
> are fundamentally required, which are certainly present on other
> platforms)? After all, this is just a type definition and a few manifest
> constants - I'm not asking that their implementation should be done
> for other than the case you care about right now.

Ok, I will change this in the next version. Indeed there is nothing special 
for x86 in these two hcalls. 
Thanks,
Wei 

> Jan




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