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From: Paul Durrant <xadimgnik@gmail.com>
Message-ID: <15a9176e-9221-44b9-b8df-910c0c16ddc2@xen.org>
Date: Fri, 19 Apr 2024 16:55:47 +0100
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Subject: Re: [PATCH 08/10] KVM: x86: Remove periodic global clock updates
To: David Woodhouse <dwmw2@infradead.org>, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
 Sean Christopherson <seanjc@google.com>, Thomas Gleixner
 <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
 Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>,
 x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
 Shuah Khan <shuah@kernel.org>, linux-doc@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
 Oliver Upton <oliver.upton@linux.dev>, Marcelo Tosatti
 <mtosatti@redhat.com>, jalliste@amazon.co.uk, sveith@amazon.de
References: <20240418193528.41780-1-dwmw2@infradead.org>
 <20240418193528.41780-9-dwmw2@infradead.org>
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On 18/04/2024 20:34, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> This effectively reverts commit 332967a3eac0 ("x86: kvm: introduce
> periodic global clock updates"). The periodic update was introduced to
> propagate NTP corrections to the guest KVM clock, when the KVM clock was
> based on CLOCK_MONOTONIC.
> 
> However, commit 53fafdbb8b21 ("KVM: x86: switch KVMCLOCK base to
> monotonic raw clock") switched to using CLOCK_MONOTONIC_RAW as the basis
> for the KVM clock, avoiding the NTP frequency skew altogether.
> 
> So the periodic update serves no purpose. Remove it.
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>   arch/x86/kvm/x86.c | 25 -------------------------
>   1 file changed, 25 deletions(-)
> 

Reviewed-by: Paul Durrant <paul@xen.org>