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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> 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.

Jan


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