From: Thomas Gleixner <tglx@linutronix.de>
To: zhenwei pi <pizhenwei@bytedance.com>, pbonzini@redhat.com
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, zhenwei pi <pizhenwei@bytedance.com>
Subject: Re: [PATCH v2 2/2] KVM: x86: use x86_get_freq to get freq for kvmclock
Date: Thu, 02 Dec 2021 03:48:41 +0100 [thread overview]
Message-ID: <877dcn7md2.ffs@tglx> (raw)
In-Reply-To: <20211201024650.88254-3-pizhenwei@bytedance.com>
On Wed, Dec 01 2021 at 10:46, zhenwei pi wrote:
> If the host side supports APERF&MPERF feature, the guest side may get
> mismatched frequency.
>
> KVM uses x86_get_cpufreq_khz() to get the same frequency for guest side.
>
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> ---
> arch/x86/kvm/x86.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 5a403d92833f..125ed3c8b21a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8305,10 +8305,8 @@ static void tsc_khz_changed(void *data)
>
> if (data)
> khz = freq->new;
> - else if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
> - khz = cpufreq_quick_get(raw_smp_processor_id());
> if (!khz)
> - khz = tsc_khz;
> + khz = x86_get_cpufreq_khz(raw_smp_processor_id());
my brain compiler tells me that this is broken.
next prev parent reply other threads:[~2021-12-02 2:48 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-01 2:46 [PATCH v2 0/2] Introduce x86_get_cpufreq_khz() zhenwei pi
2021-12-01 2:46 ` [PATCH v2 1/2] x86/cpu: " zhenwei pi
2021-12-02 22:25 ` Peter Zijlstra
2021-12-03 7:34 ` zhenwei pi
2021-12-04 10:46 ` Peter Zijlstra
2021-12-01 2:46 ` [PATCH v2 2/2] KVM: x86: use x86_get_freq to get freq for kvmclock zhenwei pi
2021-12-02 2:48 ` Thomas Gleixner [this message]
2021-12-02 5:26 ` zhenwei pi
2021-12-02 7:19 ` Maxim Levitsky
2021-12-02 22:45 ` Peter Zijlstra
2021-12-03 7:53 ` Maxim Levitsky
2021-12-04 10:44 ` Peter Zijlstra
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