From: Paul Durrant <xadimgnik@gmail.com>
To: David Woodhouse <dwmw2@infradead.org>,
Paul Durrant <xadimgnik@gmail.com>,
Jack Allister <jalliste@amazon.com>
Cc: bp@alien8.de, corbet@lwn.net, dave.hansen@linux.intel.com,
hpa@zytor.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com,
pbonzini@redhat.com, seanjc@google.com, tglx@linutronix.de,
x86@kernel.org, Dongli Zhang <dongli.zhang@oracle.com>
Subject: Re: [PATCH v2 1/2] KVM: x86: Add KVM_[GS]ET_CLOCK_GUEST for accurate KVM clock migration
Date: Wed, 10 Apr 2024 13:43:25 +0100 [thread overview]
Message-ID: <26bfe5ec-e583-458d-8e43-e5ecdc5883cc@xen.org> (raw)
In-Reply-To: <ED45576F-F1F4-452F-80CF-AACC723BFE7E@infradead.org>
On 10/04/2024 13:09, David Woodhouse wrote:
> On 10 April 2024 11:29:13 BST, Paul Durrant <xadimgnik@gmail.com> wrote:
>> On 10/04/2024 10:52, Jack Allister wrote:
>>> + * It's possible that this vCPU doesn't have a HVCLOCK configured
>>> + * but the other vCPUs may. If this is the case calculate based
>>> + * upon the time gathered in the seqcount but do not update the
>>> + * vCPU specific PVTI. If we have one, then use that.
>>
>> Given this is a per-vCPU ioctl, why not fail in the case the vCPU doesn't have HVCLOCK configured? Or is your intention that a GET/SET should always work if TSC is stable?
>
> It definitely needs to work for SET even when the vCPU hasn't been run yet (and doesn't have a hvclock in vcpu->arch.hv_clock).
So would it make sense to set up hvclock earlier?
next prev parent reply other threads:[~2024-04-10 12:43 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-08 22:07 [PATCH 0/2] Add API to correct KVM/PV clock drift Jack Allister
2024-04-08 22:07 ` [PATCH 1/2] KVM: x86: Add KVM_[GS]ET_CLOCK_GUEST for KVM clock drift fixup Jack Allister
2024-04-09 0:34 ` Dongli Zhang
2024-04-09 3:50 ` David Woodhouse
2024-04-10 10:08 ` Allister, Jack
2024-04-08 22:07 ` [PATCH 2/2] KVM: selftests: Add KVM/PV clock selftest to prove timer drift correction Jack Allister
2024-04-09 0:43 ` Dongli Zhang
2024-04-09 4:23 ` David Woodhouse
2024-04-10 10:15 ` Allister, Jack
2024-04-11 13:28 ` David Woodhouse
2024-04-19 17:13 ` Chen, Zide
[not found] ` <17F1A2E9-6BAD-40E7-ACDD-B110CFC124B3@infradead.org>
2024-04-19 18:43 ` David Woodhouse
2024-04-19 23:54 ` Chen, Zide
2024-04-20 10:32 ` David Woodhouse
2024-04-20 16:03 ` David Woodhouse
2024-04-22 22:02 ` Chen, Zide
2024-04-23 7:49 ` David Woodhouse
2024-04-23 17:59 ` Chen, Zide
2024-04-23 21:02 ` David Woodhouse
2024-04-24 12:58 ` David Woodhouse
2024-04-19 19:34 ` David Woodhouse
2024-04-19 23:53 ` Chen, Zide
2024-04-10 9:52 ` [PATCH v2 0/2] Add API for accurate KVM/PV clock migration Jack Allister
2024-04-10 9:52 ` [PATCH v2 1/2] KVM: x86: Add KVM_[GS]ET_CLOCK_GUEST for accurate KVM " Jack Allister
2024-04-10 10:29 ` Paul Durrant
2024-04-10 12:09 ` David Woodhouse
2024-04-10 12:43 ` Paul Durrant [this message]
2024-04-17 19:50 ` David Woodhouse
2024-04-15 7:16 ` David Woodhouse
2024-04-10 9:52 ` [PATCH v2 2/2] KVM: selftests: Add KVM/PV clock selftest to prove timer correction Jack Allister
2024-04-10 10:36 ` Paul Durrant
2024-04-12 8:19 ` Dongli Zhang
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