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Message-ID: <a6723ac9e0169839cb33e8022a47c2de213866ac.camel@infradead.org>
Subject: Re: [RFC PATCH 0/10] Cleaning up the KVM clock mess
From: David Woodhouse <dwmw2@infradead.org>
To: 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>,  Paul Durrant <paul@xen.org>, 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, Dongli Zhang
 <dongli.zhang@oracle.com>
Date: Fri, 19 Apr 2024 13:52:49 +0100
In-Reply-To: <20240418193528.41780-1-dwmw2@infradead.org>
References: <20240418193528.41780-1-dwmw2@infradead.org>
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On Thu, 2024-04-18 at 20:34 +0100, David Woodhouse wrote:
>=20
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KVM: x86: Remove periodic global clock upd=
ates
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KVM: x86: Kill KVM_REQ_GLOBAL_CLOCK_UPDATE

Meh, I might have to put those back. They were originally introduced to
cope with NTP frequency skew which is no longer a problem, but we now
know there's a systemic skew even between the host CLOCK_MONOTONIC_RAW
and the KVM clock as calculated via the guest's TSC.

So at least when !ka->use_master_clock I think the forced resync does
need to happen.


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