On Fri, Jan 13, 2017 at 04:18:04PM +0100, Radim Krcmar wrote: > 2017-01-13 10:01-0200, Marcelo Tosatti: > > Expose the realtime host clock and save the TSC value > > used for the clock calculation. > > > > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > > > --- > > arch/x86/kvm/x86.c | 38 ++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 38 insertions(+) > > > > Index: kvm-ptpdriver/arch/x86/kvm/x86.c > > =================================================================== > > --- kvm-ptpdriver.orig/arch/x86/kvm/x86.c 2017-01-13 08:59:03.015895353 -0200 > > +++ kvm-ptpdriver/arch/x86/kvm/x86.c 2017-01-13 09:04:46.581415259 -0200 > > @@ -1139,6 +1139,8 @@ > > > > u64 boot_ns; > > u64 nsec_base; > > + u64 wall_time_sec; > > + u64 wall_time_snsec; > > The leading "s" in "snsec" looks like a copy-paste residue. > > > }; > > > > static struct pvclock_gtod_data pvclock_gtod_data; > > @@ -1162,6 +1164,9 @@ > > vdata->boot_ns = boot_ns; > > vdata->nsec_base = tk->tkr_mono.xtime_nsec; > > > > + vdata->wall_time_sec = tk->xtime_sec; > > + vdata->wall_time_snsec = tk->tkr_mono.xtime_nsec; > > Using tk->tkr_mono offsets for real time seems wrong -- what happens if > the real time is half a second shifted from monotonic time? > > If it's ok, then vdata->nsec_base == vdata->wall_time_snsec, so we don't > need it. > > > + > > write_seqcount_end(&vdata->seq); > > } > > #endif > > @@ -1623,6 +1628,28 @@ > > return mode; > > } > > > > +static int do_realtime(struct timespec *ts, cycle_t *cycle_now) > > This is too similar to do_monotonic_boot(), but I don't see a solution > that is both nice and efficient. :( > > (It usually means macros or copying pvclock_gtod_data.) PV Clock is hypervisor agnostic so both KVM and Xen can use it. Is this clock interface suppose to follow that? Thanks. > > > +{ > > + struct pvclock_gtod_data *gtod = &pvclock_gtod_data; > > + unsigned long seq; > > + int mode; > > + u64 ns; > > + > > + do { > > + seq = read_seqcount_begin(>od->seq); > > + mode = gtod->clock.vclock_mode; > > + ts->tv_sec = gtod->wall_time_sec; > > + ns = gtod->wall_time_snsec; > > + ns += vgettsc(cycle_now); > > + ns >>= gtod->clock.shift; > > + } while (unlikely(read_seqcount_retry(>od->seq, seq))); > > + > > + ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); > > + ts->tv_nsec = ns; > > + > > + return mode; > > +} > > + > > /* returns true if host is using tsc clocksource */ > > static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now) > > { > > @@ -1632,6 +1659,17 @@ > > > > return do_monotonic_boot(kernel_ns, cycle_now) == VCLOCK_TSC; > > } > > + > > +/* returns true if host is using tsc clocksource */ > > +static bool kvm_get_walltime_and_clockread(struct timespec *ts, > > + cycle_t *cycle_now) > > +{ > > + /* checked again under seqlock below */ > > + if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC) > > + return false; > > + > > + return do_realtime(ts, cycle_now) == VCLOCK_TSC; > > +} > > #endif > > > > /* > > > > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html