[focal:linux-azure/eoan:linux-azure][PATCH 0/2] LP#1875467: Enable invariant TSC support
Juerg Haefliger
juerg.haefliger at canonical.com
Wed Jun 10 10:33:30 UTC 2020
On Tue, 9 Jun 2020 23:32:53 -0600
Kelsey Skunberg <kelsey.skunberg at canonical.com> wrote:
> BugLink: http://bugs.launchpad.net/bugs/1875467
That should be https://...
...Juerg
> Microsoft would like to request two commits in all releases supported on
> Azure. These commits benefit SAP workloads.
>
> These requested commits will enable support for Invariant TSC in Linux
> guest VMs. The invariant TSC means that the TSC continues at a fixed
> rate regardless of the C-state or frequency of the processor (as long as
> the processor remains in the ACPI S0 state).
>
> These patches will allow guests to access the
> HvSyntheticInvariantTscControl MSR and set bit 0 of this synthetic MSR,
> which then enables the InvariantTSC feature. After setting the synthetic
> MSR, CPUID will enumerate support for InvariantTSC.
>
> The following two commits enable support:
> 9e0333ae38ee ("clocksource/drivers/hyper-v: Set TSC clocksource as
> default w/ InvariantTSC")
> dce7cd62754b ("x86/hyperv: Allow guests to enable InvariantTSC")
>
> Clean cherry-pick for both commits.
>
> Andrea Parri (2):
> x86/hyperv: Allow guests to enable InvariantTSC
> clocksource/drivers/hyper-v: Set TSC clocksource as default w/
> InvariantTSC
>
> arch/x86/include/asm/hyperv-tlfs.h | 5 +++++
> arch/x86/kernel/cpu/mshyperv.c | 7 ++++++-
> drivers/clocksource/hyperv_timer.c | 12 ++++++++++--
> 3 files changed, 21 insertions(+), 3 deletions(-)
>
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