Re: [PATCH RFC 2/6] x86/hyper-v: add a function to read both TSC and TSC page value simulateneously

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 01/12/2017 18:29, Stephen Hemminger wrote:
>> +static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
>> +				       u64 *cur_tsc)
>> +{
>> +	*cur_tsc = rdtsc();
>> +
>> +	return cur_tsc;
> Why do return and setting by reference. Looks like an ugly API.

This is the fallback implementation for !CONFIG_HYPERV_TSCPAGE, which
explains why it's ugly, but why is it needed at all (or it could just
BUG())?

Thanks,

Paolo