Author: bryanv
Date: Wed Feb 4 08:33:04 2015
New Revision: 278184
URL: https://svnweb.freebsd.org/changeset/base/278184
Log:
Add interface to derive a TSC frequency from the pvclock
This can later use this to determine the TSC frequency like is done with
VMware, instead of using a DELAY loop that is not always accurate in an VM.
MFC after: 1 month
Modified:
head/sys/x86/include/pvclock.h
head/sys/x86/x86/pvclock.c
Modified: head/sys/x86/include/pvclock.h
==============================================================================
--- head/sys/x86/include/pvclock.h Wed Feb 4 08:26:43 2015
(r278183)
+++ head/sys/x86/include/pvclock.h Wed Feb 4 08:33:04 2015
(r278184)
@@ -51,6 +51,7 @@ struct pvclock_wall_clock {
void pvclock_resume(void);
uint64_t pvclock_get_last_cycles(void);
+uint64_t pvclock_tsc_freq(struct pvclock_vcpu_time_info *ti);
uint64_t pvclock_get_timecount(struct pvclock_vcpu_time_info *ti);
void pvclock_get_wallclock(struct pvclock_wall_clock *wc,
struct timespec *ts);
Modified: head/sys/x86/x86/pvclock.c
==============================================================================
--- head/sys/x86/x86/pvclock.c Wed Feb 4 08:26:43 2015 (r278183)
+++ head/sys/x86/x86/pvclock.c Wed Feb 4 08:33:04 2015 (r278184)
@@ -58,6 +58,21 @@ pvclock_get_last_cycles(void)
return (atomic_load_acq_64(&pvclock_last_cycles));
}
+uint64_t
+pvclock_tsc_freq(struct pvclock_vcpu_time_info *ti)
+{
+ uint64_t freq;
+
+ freq = (1000000000ULL << 32) / ti->tsc_to_system_mul;
+
+ if (ti->tsc_shift < 0)
+ freq <<= -ti->tsc_shift;
+ else
+ freq >>= ti->tsc_shift;
+
+ return (freq);
+}
+
/*
* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
* yielding a 64-bit result.
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