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authorPaolo Bonzini <pbonzini@redhat.com>2016-09-01 14:21:03 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2016-09-20 09:26:15 +0200
commit108b249c453dd7132599ab6dc7e435a7036c193f (patch)
treeeb600c0558d7032bc1b0c62066f74ac109bd4fd7 /arch/x86/entry
parent67198ac3f37ffb150f1c95fae16b597339eabc9d (diff)
KVM: x86: introduce get_kvmclock_ns
Introduce a function that reads the exact nanoseconds value that is provided to the guest in kvmclock. This crystallizes the notion of kvmclock as a thin veneer over a stable TSC, that the guest will (hopefully) convert with NTP. In other words, kvmclock is *not* a paravirtualized host-to-guest NTP. Drop the get_kernel_ns() function, that was used both to get the base value of the master clock and to get the current value of kvmclock. The former use is replaced by ktime_get_boot_ns(), the latter is the purpose of get_kernel_ns(). This also allows KVM to provide a Hyper-V time reference counter that is synchronized with the time that is computed from the TSC page. Reviewed-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/vdso/vclock_gettime.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index 94d54d0defa7..02223cb4bcfd 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -129,7 +129,7 @@ static notrace cycle_t vread_pvclock(int *mode)
return 0;
}
- ret = __pvclock_read_cycles(pvti);
+ ret = __pvclock_read_cycles(pvti, rdtsc_ordered());
} while (pvclock_read_retry(pvti, version));
/* refer to vread_tsc() comment for rationale */