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Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

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On Tue, 14 Feb 2017, Vitaly Kuznetsov wrote:

> Hi,
> 
> while we're still waiting for a definitive ACK from Microsoft that the
> algorithm is good for SMP case (as we can't prevent the code in vdso from
> migrating between CPUs) I'd like to send v2 with some modifications to keep
> the discussion going.

Migration is irrelevant. The TSC page is guest global so updates will
happen on some (random) host CPU and therefor you need the usual barriers
like we have them in our seqcounts unless an access to the sequence will
trap into the host, which would defeat the whole purpose of the TSC page.

Thanks,

	tglx

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[PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-14 13:50 +0100
  [PATCH v2 1/3] x86/hyperv: implement hv_get_tsc_page() Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-14 13:50 +0100
  [PATCH v2 2/3] x86/hyperv: move TSC reading method to asm/mshyperv.h Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-14 13:50 +0100
  [PATCH v2 3/3] x86/vdso: Add VCLOCK_HVCLOCK vDSO clock read method Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-14 13:50 +0100
  RE: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support KY Srinivasan <kys@microsoft.com> - 2017-02-14 15:50 +0100
  Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource  support Thomas Gleixner <tglx@linutronix.de> - 2017-02-14 16:00 +0100
    Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-14 17:00 +0100
      Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Andy Lutomirski <luto@amacapital.net> - 2017-02-14 18:40 +0100
        Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-15 15:10 +0100
          Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource  support Thomas Gleixner <tglx@linutronix.de> - 2017-02-16 19:00 +0100
            Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-02-17 11:20 +0100
              Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource  support Thomas Gleixner <tglx@linutronix.de> - 2017-02-17 11:40 +0100
              Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Andy Lutomirski <luto@amacapital.net> - 2017-02-17 18:10 +0100
                Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource  support Thomas Gleixner <tglx@linutronix.de> - 2017-02-17 19:00 +0100

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