Subject: Re: [PATCH RFC 0/6] x86/kvm/hyperv: stable clocksorce for L2 guests
 when running nested KVM on Hyper-V
To: Vitaly Kuznetsov <vkuznets@redhat.com>, kvm@vger.kernel.org,
        x86@kernel.org
Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Andy Lutomirski <luto@kernel.org>, linux-kernel@vger.kernel.org,
        devel@linuxdriverproject.org
References: <20171201131321.918-1-vkuznets@redhat.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <a600c07f-f79f-e238-108f-ada0a81567a9@redhat.com>
Date: Fri, 1 Dec 2017 17:11:24 +0100
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On 01/12/2017 14:13, Vitaly Kuznetsov wrote:
> Currently, KVM passes PVCLOCK_TSC_STABLE_BIT to its guests when running in
> so called 'masterclock' mode and this is only possible when the clocksource
> on the host is TSC. When running nested on Hyper-V we're using a different
> clocksource in L1 (Hyper-V TSC Page) which can actually be used for
> masterclock. This series brings the required support.
> 
> Making KVM work with TSC page clocksource is relatively easy, it is done in
> PATCH 5 of the series. All the rest is required to support L1 migration
> when TSC frequency changes, we use a special feature from Hyper-V to do
> the job.

This looks great.  If the Hyper-V folks can provide a topic branch with
patches 1-4 in it, we can merge it.

Thanks,

Paolo