Commit c0e96acf authored by Dexuan Cui's avatar Dexuan Cui Committed by Wei Liu
Browse files

clocksource: hyper-v: make sure Invariant-TSC is used if it is available 



If Hyper-V TSC page is unavailable and Invariant-TSC is available,
currently hyperv_cs_msr (rather than Invariant-TSC) is used by default.

Use Invariant-TSC by default by downgrading hyperv_cs_msr.rating in
hv_init_tsc_clocksource(), if Invariant-TSC is available.

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230408210339.15085-1-decui@microsoft.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 2c6ba421

drivers/clocksource/hyperv_timer.c

+3 −3
Original line number Diff line number Diff line
@@ -517,9 +517,6 @@ static bool __init hv_init_tsc_clocksource(void) 
{

	union hv_reference_tsc_msr tsc_msr;



	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))

		return false;



	/*

	 * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly

	 * handles frequency and offset changes due to live migration,
@@ -536,6 +533,9 @@ static bool __init hv_init_tsc_clocksource(void) 
		hyperv_cs_msr.rating = 250;

	}



	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))

		return false;



	hv_read_reference_counter = read_hv_clock_tsc;



	/*