From: Keqian Zhu <zhukeqian1@huawei.com>
To: Marc Zyngier <maz@kernel.org>, <kvm@vger.kernel.org>,
<kvmarm@lists.cs.columbia.edu>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <linux-s390@vger.kernel.org>,
<linux-sh@vger.kernel.org>
Cc: Rich Felker <dalias@libc.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Peter Zijlstra <peterz@infradead.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
Heiko Carstens <hca@linux.ibm.com>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>, <nathan@kernel.org>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
<kernel-team@android.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH 1/5] KVM: arm64: Divorce the perf code from oprofile helpers
Date: Thu, 15 Apr 2021 14:59:26 +0800 [thread overview]
Message-ID: <baa268cf-c92d-6b97-da4c-e7da2a9ccb7a@huawei.com> (raw)
In-Reply-To: <20210414134409.1266357-2-maz@kernel.org>
Hi Marc,
On 2021/4/14 21:44, Marc Zyngier wrote:
> KVM/arm64 is the sole user of perf_num_counters(), and really
> could do without it. Stop using the obsolete API by relying on
> the existing probing code.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/kvm/perf.c | 7 +------
> arch/arm64/kvm/pmu-emul.c | 2 +-
> include/kvm/arm_pmu.h | 4 ++++
> 3 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
> index 739164324afe..b8b398670ef2 100644
> --- a/arch/arm64/kvm/perf.c
> +++ b/arch/arm64/kvm/perf.c
> @@ -50,12 +50,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
>
> int kvm_perf_init(void)
> {
> - /*
> - * Check if HW_PERF_EVENTS are supported by checking the number of
> - * hardware performance counters. This could ensure the presence of
> - * a physical PMU and CONFIG_PERF_EVENT is selected.
> - */
> - if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0)
> + if (kvm_pmu_probe_pmuver() != 0xf)
The probe() function may be called many times (kvm_arm_pmu_v3_set_attr also calls it).
I don't know whether the first calling is enough. If so, can we use a static variable
in it, so the following calling can return the result right away?
Thanks,
Keqian
next prev parent reply other threads:[~2021-04-15 6:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-14 13:44 [PATCH 0/5] perf: oprofile spring cleanup Marc Zyngier
2021-04-14 13:44 ` [PATCH 1/5] KVM: arm64: Divorce the perf code from oprofile helpers Marc Zyngier
2021-04-15 6:59 ` Keqian Zhu [this message]
[not found] ` <87h7k7n81z.wl-maz@kernel.org>
2021-04-15 11:34 ` Keqian Zhu
2021-04-22 10:43 ` Will Deacon
2021-04-14 13:44 ` [PATCH 2/5] arm64: Get rid of oprofile leftovers Marc Zyngier
2021-04-22 10:45 ` Will Deacon
2021-04-14 13:44 ` [PATCH 3/5] s390: " Marc Zyngier
2021-04-15 10:38 ` Heiko Carstens
2021-04-15 10:47 ` Marc Zyngier
2021-04-15 12:12 ` Heiko Carstens
2021-04-14 13:44 ` [PATCH 4/5] sh: " Marc Zyngier
2021-04-14 19:09 ` Geert Uytterhoeven
2021-04-14 13:44 ` [PATCH 5/5] perf: " Marc Zyngier
2021-04-22 10:47 ` Will Deacon
2021-04-22 12:48 ` [PATCH 0/5] perf: oprofile spring cleanup Marc Zyngier
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