x86: pvclock: create helper for pvclock data retrieval

Originally from Jeremy Fitzhardinge.

So code can be reused.

Acked-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 30 insertions, 14 deletions

diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index c59cc97fe6c1..47e25d464104 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -56,4 +56,32 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
         return product;
 }
 
+static __always_inline
+u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
+{
+        u64 delta = __native_read_tsc() - src->tsc_timestamp;
+        return pvclock_scale_delta(delta, src->tsc_to_system_mul,
+                                   src->tsc_shift);
+}
+
+static __always_inline
+unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
+                               cycle_t *cycles, u8 *flags)
+{
+        unsigned version;
+        cycle_t ret, offset;
+        u8 ret_flags;
+
+        version = src->version;
+        rdtsc_barrier();
+        offset = pvclock_get_nsec_offset(src);
+        ret = src->system_time + offset;
+        ret_flags = src->flags;
+        rdtsc_barrier();
+
+        *cycles = ret;
+        *flags = ret_flags;
+        return version;
+}
+
 #endif /* _ASM_X86_PVCLOCK_H */
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index d59e60661794..a7d90910c61a 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -26,13 +26,6 @@ void pvclock_set_flags(u8 flags)
         valid_flags = flags;
 }
 
-static u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
-{
-        u64 delta = native_read_tsc() - src->tsc_timestamp;
-        return pvclock_scale_delta(delta, src->tsc_to_system_mul,
-                                   src->tsc_shift);
-}
-
 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)
 {
         u64 pv_tsc_khz = 1000000ULL << 32;
@@ -55,17 +48,12 @@ void pvclock_resume(void)
 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
 {
         unsigned version;
-        cycle_t ret, offset;
+        cycle_t ret;
         u64 last;
         u8 flags;
 
         do {
-                version = src->version;
-                rdtsc_barrier();
-                offset = pvclock_get_nsec_offset(src);
-                ret = src->system_time + offset;
-                flags = src->flags;
-                rdtsc_barrier();
+                version = __pvclock_read_cycles(src, &ret, &flags);
         } while ((src->version & 1) || version != src->version);
 
         if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&