From: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
To: <joro@8bytes.org>, <bp@alien8.de>, <peterz@infradead.org>,
<mingo@redhat.com>, <acme@kernel.org>
Cc: <andihartmann@freenet.de>, <vw@iommu.org>, <labbott@redhat.com>,
<linux-kernel@vger.kernel.org>,
<iommu@lists.linux-foundation.org>,
"Suravee Suthikulpanit" <Suravee.Suthikulpanit@amd.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: [PATCH V5 01/10] perf/amd/iommu: Misc fix up perf_iommu_read
Date: Tue, 23 Feb 2016 08:12:35 -0600 [thread overview]
Message-ID: <1456236764-1569-2-git-send-email-Suravee.Suthikulpanit@amd.com> (raw)
In-Reply-To: <1456236764-1569-1-git-send-email-Suravee.Suthikulpanit@amd.com>
This patch contains the follow minor fixup:
* Fixed overflow handling since u64 delta would lose the MSB sign bit.
* Remove unnecessary local64_set().
* Coding style and make use of GENMASK_ULL macro.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/events/amd/iommu.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index 629bc70..9da0d16 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -314,9 +314,8 @@ static void perf_iommu_start(struct perf_event *event, int flags)
static void perf_iommu_read(struct perf_event *event)
{
- u64 count = 0ULL;
- u64 prev_raw_count = 0ULL;
- u64 delta = 0ULL;
+ u64 cnt, prev;
+ s64 delta;
struct hw_perf_event *hwc = &event->hw;
pr_debug("perf: amd_iommu:perf_iommu_read\n");
@@ -325,18 +324,20 @@ static void perf_iommu_read(struct perf_event *event)
IOMMU_PC_COUNTER_REG, &count, false);
/* IOMMU pc counter register is only 48 bits */
- count &= 0xFFFFFFFFFFFFULL;
+ cnt &= GENMASK_ULL(48, 0);
- prev_raw_count = local64_read(&hwc->prev_count);
- if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
- count) != prev_raw_count)
- return;
+ prev = local64_read(&hwc->prev_count);
- /* Handling 48-bit counter overflowing */
- delta = (count << COUNTER_SHIFT) - (prev_raw_count << COUNTER_SHIFT);
+ /*
+ * Since we do not enable counter overflow interrupts,
+ * we do not have to worry about prev_count changing on us.
+ */
+ local64_set(&hwc->prev_count, cnt);
+
+ /* Handle 48-bit counter overflow */
+ delta = (cnt << COUNTER_SHIFT) - (prev << COUNTER_SHIFT);
delta >>= COUNTER_SHIFT;
local64_add(delta, &event->count);
-
}
static void perf_iommu_stop(struct perf_event *event, int flags)
--
1.9.1
next prev parent reply other threads:[~2016-02-23 14:13 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-23 14:12 [PATCH V5 00/10] perf/amd/iommu: Enable multi-IOMMU support Suravee Suthikulpanit
2016-02-23 14:12 ` Suravee Suthikulpanit [this message]
2016-02-23 14:12 ` [PATCH V5 02/10] perf/amd/iommu: Consolidate and move perf_event_amd_iommu header Suravee Suthikulpanit
2016-03-12 13:22 ` Peter Zijlstra
2016-03-14 5:26 ` Suravee Suthikulpanit
2016-03-14 9:58 ` Peter Zijlstra
2016-03-14 13:37 ` Suravee Suthikulpanit
2016-03-14 14:19 ` Borislav Petkov
2016-03-14 16:39 ` Peter Zijlstra
2016-03-15 0:39 ` Suravee Suthikulpanit
2016-03-15 8:44 ` Peter Zijlstra
2016-03-15 10:40 ` Borislav Petkov
2016-03-15 10:53 ` Peter Zijlstra
2016-03-18 7:07 ` Suravee Suthikulpanit
2016-03-18 9:04 ` Borislav Petkov
2016-03-18 9:09 ` Suravee Suthikulpanit
2016-03-18 9:29 ` Borislav Petkov
2016-03-18 10:06 ` Suravee Suthikulpanit
2016-03-18 10:39 ` Borislav Petkov
2016-03-18 11:11 ` Joerg Roedel
2016-03-18 11:33 ` Borislav Petkov
2016-02-23 14:12 ` [PATCH V5 03/10] perf/amd/iommu: Modify functions to query max banks and counters Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 04/10] perf/amd/iommu: Modify IOMMU API to allow specifying IOMMU index Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 05/10] perf/amd/iommu: Declare pr_fmt and remove unnecessary pr_debug Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 06/10] perf/amd/iommu: Clean up perf_iommu_enable_event Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 07/10] perf/amd/iommu: Clean up get_next_available_iommu_bnk_cntr Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 08/10] perf/amd/iommu: Rename struct perf_amd_iommu to perf_iommu Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 09/10] iommu/amd: Introduce amd_iommu_get_num_iommus() Suravee Suthikulpanit
2016-02-23 14:12 ` [PATCH V5 10/10] perf/amd/iommu: Enable support for multiple IOMMUs Suravee Suthikulpanit
2016-02-25 14:54 ` [PATCH V5 00/10] perf/amd/iommu: Enable multi-IOMMU support Joerg Roedel
2016-03-07 1:44 ` Suravee Suthikulpanit
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