From: Peter Zijlstra <peterz@infradead.org>
To: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
joro@8bytes.org, bp@alien8.de, mingo@redhat.com
Subject: Re: [PATCH v8 9/9] perf/amd/iommu: Enable support for multiple IOMMUs
Date: Thu, 23 Feb 2017 19:11:16 +0100 [thread overview]
Message-ID: <20170223181116.GJ6515@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <a2d532c4-2a58-f892-eb75-ffc94f0a125a@amd.com>
On Fri, Feb 24, 2017 at 12:43:19AM +0700, Suravee Suthikulpanit wrote:
> >Also, who cares about the banks, why is this exposed?
>
> The bank and counter values are not exposed to the user-space.
> The amd_iommu PMU only expose, csource, devid, domid, pasid, devid_mask,
> domid_mask, and pasid_mask as event attributes.
Ah good, for a little while I was worried the BANK stuff came from
userspace; I misread extra_reg.config and extra_reg.reg, the former
being perf_event_attr::config1 and the latter holding the bank thing.
> >That is, I would very much expect a linear range of counters. You can
> >always decompose this counter number if you really need to somewhere
> >down near the hardware accessors.
> >
>
> Actually, the counters are treated as linear range of counters. For example,
> the IOMMU hardware has 2 banks with 4 counters/bank. So, we have total of 8
> counters. The driver then assigns an index to each events when an event is added.
> Here, the bank/counter are derived from the assigned index, and stored in
> the perf_event as bank and counter values.
>
> 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.
next prev parent reply other threads:[~2017-02-23 18:44 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 7:23 [PATCH v8 0/9] perf/amd/iommu: Enable multi-IOMMU support Suravee Suthikulpanit
2017-01-16 7:23 ` [PATCH v8 1/9] perf/amd/iommu: Declare pr_fmt and remove unnecessary pr_debug Suravee Suthikulpanit
2017-01-16 7:23 ` [PATCH v8 2/9] perf/amd/iommu: Clean up perf_iommu_enable_event Suravee Suthikulpanit
2017-01-18 18:20 ` Borislav Petkov
2017-01-16 7:23 ` [PATCH v8 3/9] perf/amd/iommu: Misc fix up perf_iommu_read Suravee Suthikulpanit
2017-01-19 10:01 ` Borislav Petkov
2017-01-23 12:33 ` Peter Zijlstra
2017-02-07 4:50 ` Suravee Suthikulpanit
2017-01-16 7:23 ` [PATCH v8 4/9] iommu/amd: Introduce amd_iommu_get_num_iommus() Suravee Suthikulpanit
2017-01-19 18:41 ` Borislav Petkov
2017-01-16 7:23 ` [PATCH v8 5/9] perf/amd/iommu: Modify functions to query max banks and counters Suravee Suthikulpanit
2017-01-22 19:53 ` Borislav Petkov
2017-01-16 7:23 ` [PATCH v8 6/9] perf/amd/iommu: Modify amd_iommu_pc_get_set_reg_val() API to allow specifying IOMMU index Suravee Suthikulpanit
2017-01-22 19:53 ` Borislav Petkov
2017-01-16 7:23 ` [PATCH v8 7/9] perf/amd/iommu: Check return value when set and get counter value Suravee Suthikulpanit
2017-01-22 19:53 ` Borislav Petkov
2017-01-23 12:31 ` Peter Zijlstra
2017-01-16 7:23 ` [PATCH v8 8/9] perf/amd/iommu: Fix sysfs perf attribute groups Suravee Suthikulpanit
2017-01-22 19:54 ` Borislav Petkov
2017-01-16 7:23 ` [PATCH v8 9/9] perf/amd/iommu: Enable support for multiple IOMMUs Suravee Suthikulpanit
2017-01-22 19:55 ` Borislav Petkov
2017-02-07 1:42 ` Suravee Suthikulpanit
2017-01-25 9:46 ` Peter Zijlstra
2017-01-25 9:55 ` Borislav Petkov
2017-02-07 1:58 ` Suravee Suthikulpanit
2017-02-07 1:57 ` Suravee Suthikulpanit
2017-02-14 12:31 ` Peter Zijlstra
2017-02-23 17:43 ` Suravee Suthikulpanit
2017-02-23 18:11 ` Peter Zijlstra [this message]
2017-02-23 18:20 ` Suravee Suthikulpanit
2017-01-17 15:36 ` [PATCH v8 0/9] perf/amd/iommu: Enable multi-IOMMU support Joerg Roedel
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