RE: [PATCH v2 09/13] clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX

[Michael Kelley (LINUX)]

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Sent: Friday, May 19, 2023 3:21 AM
> 
> Currently hv_read_tsc_page_tsc() (ab)uses the (valid) time value of
> U64_MAX as an error return. This breaks the clean wrap-around of the
> clock.
> 
> Modify the function signature to return a boolean state and provide
> another u64 pointer to store the actual time on success. This obviates
> the need to steal one time value and restores the full counter width.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/vdso/gettimeofday.h |   10 ++++++----
>  arch/x86/kvm/x86.c                       |    7 +++----
>  drivers/clocksource/hyperv_timer.c       |   16 +++++++++++-----
>  include/clocksource/hyperv_timer.h       |   24 +++++++++---------------
>  4 files changed, 29 insertions(+), 28 deletions(-)
> 

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>