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From: Paul Durrant <xadimgnik@gmail.com>
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
Subject: Re: [PATCH 07/10] KVM: x86: Avoid NTP frequency skew for KVM clock on 32-bit host
Date: Fri, 19 Apr 2024 16:53:49 +0100	[thread overview]
Message-ID: <b668e938-a48f-4295-a9ec-e66f0abd1bb0@xen.org> (raw)
In-Reply-To: <20240418193528.41780-8-dwmw2@infradead.org>

On 18/04/2024 20:34, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> Commit 53fafdbb8b21 ("KVM: x86: switch KVMCLOCK base to monotonic raw
> clock") did so only for 64-bit hosts, by capturing the boot offset from
> within the existing clocksource notifier update_pvclock_gtod().
> 
> That notifier was added in commit 16e8d74d2da9 ("KVM: x86: notifier for
> clocksource changes") but only on x86_64, because its original purpose
> was just to disable the "master clock" mode which is only supported on
> x86_64.
> 
> Now that the notifier is used for more than disabling master clock mode,
> (well, OK, more than a decade later but clocks are hard), enable it for
> the 32-bit build too so that get_kvmclock_base_ns() can be unaffected by
> NTP sync on 32-bit too.
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>   arch/x86/kvm/x86.c | 18 ++++++------------
>   1 file changed, 6 insertions(+), 12 deletions(-)
> 

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


  reply	other threads:[~2024-04-19 15:53 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-18 19:34 [RFC PATCH 0/10] Cleaning up the KVM clock mess David Woodhouse
2024-04-18 19:34 ` [PATCH 01/10] KVM: x86/xen: Do not corrupt KVM clock in kvm_xen_shared_info_init() David Woodhouse
2024-04-18 19:34 ` [PATCH 02/10] KVM: x86: Improve accuracy of KVM clock when TSC scaling is in force David Woodhouse
2024-04-19 15:29   ` Paul Durrant
2024-04-22 12:22   ` Paolo Bonzini
2024-04-22 15:39     ` David Woodhouse
2024-04-22 15:54       ` Paolo Bonzini
2024-04-22 16:44         ` David Woodhouse
2024-04-18 19:34 ` [PATCH 03/10] KVM: x86: Add KVM_[GS]ET_CLOCK_GUEST for accurate KVM clock migration David Woodhouse
2024-04-19 15:40   ` Paul Durrant
2024-04-19 15:49     ` David Woodhouse
2024-04-22 14:11   ` Paolo Bonzini
2024-04-22 15:02     ` David Woodhouse
2024-04-18 19:34 ` [PATCH 04/10] KVM: selftests: Add KVM/PV clock selftest to prove timer correction David Woodhouse
2024-04-19 15:44   ` Paul Durrant
2024-04-18 19:34 ` [PATCH 05/10] KVM: x86: Explicitly disable TSC scaling without CONSTANT_TSC David Woodhouse
2024-04-19 15:45   ` Paul Durrant
2024-04-18 19:34 ` [PATCH 06/10] KVM: x86: Add KVM_VCPU_TSC_SCALE and fix the documentation on TSC migration David Woodhouse
2024-04-19 15:49   ` Paul Durrant
2024-04-19 15:53     ` David Woodhouse
2024-04-18 19:34 ` [PATCH 07/10] KVM: x86: Avoid NTP frequency skew for KVM clock on 32-bit host David Woodhouse
2024-04-19 15:53   ` Paul Durrant [this message]
2024-04-18 19:34 ` [PATCH 08/10] KVM: x86: Remove periodic global clock updates David Woodhouse
2024-04-19 15:55   ` Paul Durrant
2024-04-18 19:34 ` [PATCH 09/10] KVM: x86: Kill KVM_REQ_GLOBAL_CLOCK_UPDATE David Woodhouse
2024-04-19 15:57   ` Paul Durrant
2024-04-18 19:34 ` [PATCH 10/10] KVM: x86: Fix KVM clock precision in __get_kvmclock() David Woodhouse
2024-04-19 16:07   ` Paul Durrant
2024-04-19 12:51 ` [PATCH 11/10] KVM: x86: Fix software TSC upscaling in kvm_update_guest_time() David Woodhouse
2024-04-19 12:52 ` [RFC PATCH 0/10] Cleaning up the KVM clock mess David Woodhouse

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