From: Andrey Smetanin <asmetanin@virtuozzo.com>
To: Paolo Bonzini <pbonzini@redhat.com>, <kvm@vger.kernel.org>
Cc: Gleb Natapov <gleb@kernel.org>,
Roman Kagan <rkagan@virtuozzo.com>,
"Denis V. Lunev" <den@openvz.org>, <qemu-devel@nongnu.org>
Subject: Re: [PATCH v1] kvm/x86: Hyper-V tsc page setup
Date: Fri, 22 Jan 2016 14:59:37 +0300 [thread overview]
Message-ID: <56A219A9.7000708@virtuozzo.com> (raw)
In-Reply-To: <56A21836.1010204@redhat.com>
On 01/22/2016 02:53 PM, Paolo Bonzini wrote:
>
>
> On 22/01/2016 12:31, Andrey Smetanin wrote:
>>>
>>> Sometimes the TSC is detected to be unstable and Linux switches to
>>> another clocksource. At least in that case you can get a write to the
>>> TSC page while the guest is running.
>> Sorry, now I got it, you mean host TSC is unstable and we should mark
>> guest tsc page invalid. Now I understand please ignore my prev. message.
>
> No problem. Anyhow yes, this is what I meant: a host write to the TSC
> page, not a guest write to the TSC page MSR.
>
> Usually it happens only at migration time to update the sequence---which
> I believe your patch wasn't doing either.
QEMU saves address of page inside ->msr_hv_tsc, so at restore
QEMU sets corresponding MSR and KVM setup's tsc page again.
So migration should able to work.
But if we tie TSC page
> updates to kvm_gen_update_masterclock, we get that for free when the
> migration destination calls the KVM_SET_CLOCK ioctl.
>
> Paolo
>
WARNING: multiple messages have this Message-ID (diff)
From: Andrey Smetanin <asmetanin@virtuozzo.com>
To: Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org
Cc: Gleb Natapov <gleb@kernel.org>, "Denis V. Lunev" <den@openvz.org>,
Roman Kagan <rkagan@virtuozzo.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v1] kvm/x86: Hyper-V tsc page setup
Date: Fri, 22 Jan 2016 14:59:37 +0300 [thread overview]
Message-ID: <56A219A9.7000708@virtuozzo.com> (raw)
In-Reply-To: <56A21836.1010204@redhat.com>
On 01/22/2016 02:53 PM, Paolo Bonzini wrote:
>
>
> On 22/01/2016 12:31, Andrey Smetanin wrote:
>>>
>>> Sometimes the TSC is detected to be unstable and Linux switches to
>>> another clocksource. At least in that case you can get a write to the
>>> TSC page while the guest is running.
>> Sorry, now I got it, you mean host TSC is unstable and we should mark
>> guest tsc page invalid. Now I understand please ignore my prev. message.
>
> No problem. Anyhow yes, this is what I meant: a host write to the TSC
> page, not a guest write to the TSC page MSR.
>
> Usually it happens only at migration time to update the sequence---which
> I believe your patch wasn't doing either.
QEMU saves address of page inside ->msr_hv_tsc, so at restore
QEMU sets corresponding MSR and KVM setup's tsc page again.
So migration should able to work.
But if we tie TSC page
> updates to kvm_gen_update_masterclock, we get that for free when the
> migration destination calls the KVM_SET_CLOCK ioctl.
>
> Paolo
>
next prev parent reply other threads:[~2016-01-22 11:59 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-24 9:33 [PATCH v1] kvm/x86: Hyper-V tsc page setup Andrey Smetanin
2015-12-24 9:33 ` [Qemu-devel] " Andrey Smetanin
2016-01-05 21:48 ` Peter Hornyack
2016-01-05 21:48 ` [Qemu-devel] " Peter Hornyack
2016-01-06 9:22 ` Andrey Smetanin
2016-01-06 9:22 ` [Qemu-devel] " Andrey Smetanin
2016-01-12 7:43 ` Andrey Smetanin
2016-01-12 7:43 ` [Qemu-devel] " Andrey Smetanin
2016-01-19 7:48 ` Denis V. Lunev
2016-01-19 7:48 ` [Qemu-devel] " Denis V. Lunev
2016-01-20 14:05 ` Paolo Bonzini
2016-01-20 14:05 ` [Qemu-devel] " Paolo Bonzini
2016-01-20 14:41 ` Andrey Smetanin
2016-01-20 14:41 ` [Qemu-devel] " Andrey Smetanin
2016-01-20 14:44 ` Denis V. Lunev
2016-01-20 14:44 ` [Qemu-devel] " Denis V. Lunev
2016-01-20 14:52 ` Roman Kagan
2016-01-20 14:52 ` [Qemu-devel] " Roman Kagan
2016-01-20 14:54 ` Denis V. Lunev
2016-01-20 14:54 ` [Qemu-devel] " Denis V. Lunev
2016-01-20 21:10 ` Paolo Bonzini
2016-01-20 21:10 ` [Qemu-devel] " Paolo Bonzini
2016-01-22 10:08 ` Paolo Bonzini
2016-01-22 10:08 ` [Qemu-devel] " Paolo Bonzini
2016-01-22 10:15 ` Andrey Smetanin
2016-01-22 10:15 ` [Qemu-devel] " Andrey Smetanin
2016-01-22 11:02 ` Paolo Bonzini
2016-01-22 11:02 ` [Qemu-devel] " Paolo Bonzini
2016-01-22 11:11 ` Andrey Smetanin
2016-01-22 11:11 ` [Qemu-devel] " Andrey Smetanin
2016-01-22 11:31 ` Andrey Smetanin
2016-01-22 11:31 ` [Qemu-devel] " Andrey Smetanin
2016-01-22 11:53 ` Paolo Bonzini
2016-01-22 11:53 ` [Qemu-devel] " Paolo Bonzini
2016-01-22 11:59 ` Andrey Smetanin [this message]
2016-01-22 11:59 ` Andrey Smetanin
2016-01-22 13:13 ` Andrey Smetanin
2016-01-22 13:13 ` [Qemu-devel] " Andrey Smetanin
2016-01-22 13:21 ` Paolo Bonzini
2016-01-22 13:21 ` [Qemu-devel] " Paolo Bonzini
2016-01-22 13:34 ` Andrey Smetanin
2016-01-22 13:34 ` [Qemu-devel] " Andrey Smetanin
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