Messages in this thread | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH RFC v1 05/18] clocksource/hyperv: use MSR-based access if running as root | Date | Tue, 15 Sep 2020 12:10:04 +0200 |
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Wei Liu <wei.liu@kernel.org> writes:
> Signed-off-by: Wei Liu <wei.liu@kernel.org> > --- > drivers/clocksource/hyperv_timer.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c > index 09aa44cb8a91..fe96082ce85e 100644 > --- a/drivers/clocksource/hyperv_timer.c > +++ b/drivers/clocksource/hyperv_timer.c > @@ -426,6 +426,9 @@ static bool __init hv_init_tsc_clocksource(void) > if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE)) > return false; > > + if (hv_root_partition) > + return false; > +
Out of pure curiosity,
TSC page clocksource seems to be available to the root partition (as HV_MSR_REFERENCE_TSC_AVAILABLE is set), why don't we use it? (I understand that with TSC scaling support in modern CPUs even migration is a no-issue and we can use raw TSC but this all seems to be independent from root/non-root partition question).
> hv_read_reference_counter = read_hv_clock_tsc; > phys_addr = virt_to_phys(hv_get_tsc_page());
-- Vitaly
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