ACK: [bionic:linux-azure-4.15][PATCH 0/2] LP#:1875467: Enable invariant TSC
Stefan Bader
stefan.bader at canonical.com
Wed Jun 10 08:05:15 UTC 2020
On 10.06.20 06:20, Kelsey Skunberg wrote:
> BugLink: http://bugs.launchpad.net/bugs/1875467
>
> 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") - Changes are the same, though done in
> arch/x86/hyperv/hv_init.c instead of drivers/clocksource/hyperv_timer.
>
> dce7cd62754b ("x86/hyperv: Allow guests to enable InvariantTSC") -
> required context changes to be backported.
>
> Verify
> Andrea Parri (2):
> x86/hyperv: Allow guests to enable InvariantTSC
> x86/hyperv: Set TSC clocksource as default w/ InvariantTSC
>
> arch/x86/hyperv/hv_init.c | 13 +++++++++++--
> arch/x86/include/asm/hyperv-tlfs.h | 6 ++++++
> arch/x86/kernel/cpu/mshyperv.c | 7 ++++++-
> 3 files changed, 23 insertions(+), 3 deletions(-)
>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
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