On 23/01/20 14:43, Vitaly Kuznetsov wrote:
+static s64 get_kvmclock_base_ns(void) +{
- /* Count up from boot time, but with the frequency of the raw clock. */
- return ktime_to_ns(ktime_add(ktime_get_raw(), pvclock_gtod_data.offs_boot));
+} +#else +static s64 get_kvmclock_base_ns(void) +{
- /* Master clock not used, so we can just use CLOCK_BOOTTIME. */
- return ktime_get_boottime_ns();
+} #endif
But we could've still used the RAW+offs_boot version, right? And this is just to basically preserve the existing behavior on !x86.
Yes, there's no reason to restrict the pvclock_gtod notifier to x86_64. But this is stable material so I kept it easy.
- getboottime64(&boot);
- wall_nsec = ktime_get_real_ns() - get_kvmclock_ns(kvm);
There are not that many hosts with more than 50 years uptime and likely none running Linux with live kernel patching support so I bet noone will ever see this overflowing, however, as wall_nsec is u64 and we're dealing with kvmclock here I'd suggest to add a WARN_ON().
You're off by a factor of 10, 2^64 nanoseconds are about 584 years (584*365*10^9*86400). :)
Paolo