Re: [PATCH v8 9/9] perf/amd/iommu: Enable support for multiple IOMMUs

[Suravee Suthikulpanit]

On 2/24/17 01:11, Peter Zijlstra wrote:
> > However, I have looked into reworking to not use the extra_regs, and I see
> > that the union in struct hw_perf_event currently contains various PMU-specific
> > structures (hardware, software, tracepoint, intel_cqm, itrace, amd_power,
> > and breakpoint).
> >
> > For amd_iommu PMU, we need additional registers for holding amd_iommu-specific
> > parameters. So, it seems that we can just introduce amd_iommu-specific struct
> > instead of re-using the existing structure for hardware events.
> >
> > I'm planning to add the following structure in the same union:
> >
> >     union {
> >         ......
> >                 struct { /* amd_iommu */
> >                         u8      iommu_csource;
> >                         u8      iommu_bank;
> >                         u8      iommu_cntr;
> >                         u16     iommu_devid;
> >                         u16     iommu_devid_msk;
> >                         u16     iommu_domid;
> >                         u16     iommu_domid_msk;
> >                         u32     iommu_pasid;
> >                         u32     iommu_pasid_msk;
> >                 };
> >     };
> >
> > Please let me know what you think, of if I am still missing your points.
> Yes, adding a struct to that union is fine and clarifies things. And
> just because I'm weird like that, there's a u8 hole after iommu_cntr.

Ok, I'll update this in V10 that I'll be sending out this week.

Thanks,
Suravee