Re: [PATCH v2 05/17] clocksource/hyperv: use MSR-based access if running as root
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: 2020-11-12 15:31:08
Also in:
lkml, virtualization
Wei Liu [off-list ref] writes:
Signed-off-by: Wei Liu <wei.liu@kernel.org>
In the missing commit message I'd like to see why we don't use 'TSC page' clocksource for the root partition. My guess would be that it's not available and actually we're supposed to use raw TSC value (because root partitions never migrate) but please spell it out.
quoted hunk ↗ jump to hunk
--- 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 ba04cb381cd3..269a691bd2c4 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; + hv_read_reference_counter = read_hv_clock_tsc; phys_addr = virt_to_phys(hv_get_tsc_page());
-- Vitaly