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 7/9] perf/amd/iommu: Check return value when set and get counter value
Date: Mon, 23 Jan 2017 13:31:36 +0100 [thread overview]
Message-ID: <20170123123136.GX6485@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1484551416-5440-8-git-send-email-Suravee.Suthikulpanit@amd.com>
On Mon, Jan 16, 2017 at 01:23:34AM -0600, Suravee Suthikulpanit wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>
> In, perf_iommu_start(), we need to check the return value from
> amd_iommu_set_reg(). In case of failure, we should not enable the PMU.
>
> Also, in perf_iommu_read(), we need to check the return value from
> amd_iommu_get_reg() before using the value.
>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Joerg Roedel <joro@8bytes.org>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
> arch/x86/events/amd/iommu.c | 19 +++++++++++--------
> 1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
> index 200d2e8..cc7bea4 100644
> --- a/arch/x86/events/amd/iommu.c
> +++ b/arch/x86/events/amd/iommu.c
> @@ -284,6 +284,7 @@ static void perf_iommu_disable_event(struct perf_event *event)
>
> static void perf_iommu_start(struct perf_event *event, int flags)
> {
> + u64 val;
> struct hw_perf_event *hwc = &event->hw;
>
> if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
> @@ -292,15 +293,16 @@ static void perf_iommu_start(struct perf_event *event, int flags)
> WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
> hwc->state = 0;
>
> - if (flags & PERF_EF_RELOAD) {
> - u64 prev_raw_count = local64_read(&hwc->prev_count);
> - amd_iommu_pc_set_reg(0, _GET_BANK(event), _GET_CNTR(event),
> - IOMMU_PC_COUNTER_REG, &prev_raw_count);
> - }
> + if (!(flags & PERF_EF_RELOAD))
> + return;
> +
> + val = local64_read(&hwc->prev_count) & GENMASK_ULL(48, 0);
> + if (amd_iommu_pc_set_reg(0, _GET_BANK(event), _GET_CNTR(event),
> + IOMMU_PC_COUNTER_REG, &val))
> + return;
Under what conditions could this fail? ::start() is not an interface
that expects failure, if we get this far, things should really just
work.
next prev parent reply other threads:[~2017-01-23 12:31 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 [this message]
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
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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