x86: kvm: Make kvm_get_time_and_clockread() nanoseconds based

Convert the relevant base data right away to nanoseconds instead of
doing the conversion on every readout. Reduces text size by 160 bytes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 14 insertions, 30 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 65c430512132..63832f5110b6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -984,9 +984,8 @@ struct pvclock_gtod_data {
                 u32     shift;
         } clock;
 
-        /* open coded 'struct timespec' */
-        u64             monotonic_time_snsec;
-        time_t          monotonic_time_sec;
+        u64             boot_ns;
+        u64             nsec_base;
 };
 
 static struct pvclock_gtod_data pvclock_gtod_data;
@@ -994,6 +993,9 @@ static struct pvclock_gtod_data pvclock_gtod_data;
 static void update_pvclock_gtod(struct timekeeper *tk)
 {
         struct pvclock_gtod_data *vdata = &pvclock_gtod_data;
+        u64 boot_ns;
+
+        boot_ns = ktime_to_ns(ktime_add(tk->base_mono, tk->offs_boot));
 
         write_seqcount_begin(&vdata->seq);
 
@@ -1004,17 +1006,8 @@ static void update_pvclock_gtod(struct timekeeper *tk)
         vdata->clock.mult               = tk->mult;
         vdata->clock.shift              = tk->shift;
 
-        vdata->monotonic_time_sec       = tk->xtime_sec
-                                        + tk->wall_to_monotonic.tv_sec;
-        vdata->monotonic_time_snsec     = tk->xtime_nsec
-                                        + (tk->wall_to_monotonic.tv_nsec
-                                                << tk->shift);
-        while (vdata->monotonic_time_snsec >=
-                                        (((u64)NSEC_PER_SEC) << tk->shift)) {
-                vdata->monotonic_time_snsec -=
-                                        ((u64)NSEC_PER_SEC) << tk->shift;
-                vdata->monotonic_time_sec++;
-        }
+        vdata->boot_ns                  = boot_ns;
+        vdata->nsec_base                = tk->xtime_nsec;
 
         write_seqcount_end(&vdata->seq);
 }
@@ -1371,23 +1364,22 @@ static inline u64 vgettsc(cycle_t *cycle_now)
         return v * gtod->clock.mult;
 }
 
-static int do_monotonic(struct timespec *ts, cycle_t *cycle_now)
+static int do_monotonic_boot(s64 *t, cycle_t *cycle_now)
 {
+        struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
         unsigned long seq;
-        u64 ns;
         int mode;
-        struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
+        u64 ns;
 
-        ts->tv_nsec = 0;
         do {
                 seq = read_seqcount_begin(&gtod->seq);
                 mode = gtod->clock.vclock_mode;
-                ts->tv_sec = gtod->monotonic_time_sec;
-                ns = gtod->monotonic_time_snsec;
+                ns = gtod->nsec_base;
                 ns += vgettsc(cycle_now);
                 ns >>= gtod->clock.shift;
+                ns += gtod->boot_ns;
         } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
-        timespec_add_ns(ts, ns);
+        *t = ns;
 
         return mode;
 }
@@ -1395,19 +1387,11 @@ static int do_monotonic(struct timespec *ts, cycle_t *cycle_now)
 /* returns true if host is using tsc clocksource */
 static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now)
 {
-        struct timespec ts;
-
         /* checked again under seqlock below */
         if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC)
                 return false;
 
-        if (do_monotonic(&ts, cycle_now) != VCLOCK_TSC)
-                return false;
-
-        monotonic_to_bootbased(&ts);
-        *kernel_ns = timespec_to_ns(&ts);
-
-        return true;
+        return do_monotonic_boot(kernel_ns, cycle_now) == VCLOCK_TSC;
 }
 #endif