[PATCH] KVM: x86: fix kvmclock breakage from timers branch merge

Paolo Bonzini
2014-09-04T12:58:19Z

Commit cbcf2dd3b3d4 (x86: kvm: Make kvm_get_time_and_clockread() nanoseconds
based, 2014-07-16) forgot to add tk->xtime_sec, thus breaking kvmclock on
hosts that have a reliable TSC. Add it back; and since the field boot_ns
is not anymore related to the host boot-based clock, rename boot_ns->nsec_base
and the existing nsec_base->snsec_base.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Reported-by: Chris J Arges <chris.j.arges@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8f1e22d3b286..92493e10937c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1020,8 +1020,8 @@ struct pvclock_gtod_data {
u32 shift;
} clock;

- u64 boot_ns;
u64 nsec_base;
+ u64 snsec_base;
};

static struct pvclock_gtod_data pvclock_gtod_data;
@@ -1042,8 +1042,9 @@ static void update_pvclock_gtod(struct timekeeper *tk)
vdata->clock.mult = tk->tkr.mult;
vdata->clock.shift = tk->tkr.shift;

- vdata->boot_ns = boot_ns;
- vdata->nsec_base = tk->tkr.xtime_nsec;
+ vdata->nsec_base = tk->xtime_sec * (u64)NSEC_PER_SEC
+ + boot_ns;
+ vdata->snsec_base = tk->tkr.xtime_nsec;

write_seqcount_end(&vdata->seq);
}
@@ -1413,10 +1414,10 @@ static int do_monotonic_boot(s64 *t, cycle_t *cycle_now)
do {
seq = read_seqcount_begin(&gtod->seq);
mode = gtod->clock.vclock_mode;
- ns = gtod->nsec_base;
+ ns = gtod->snsec_base;
ns += vgettsc(cycle_now);
ns >>= gtod->clock.shift;
- ns += gtod->boot_ns;
+ ns += gtod->nsec_base;
} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
*t = ns;

--
2.1.0