x86: pvclock: remove pvclock_shadow_time

Originally from Jeremy Fitzhardinge.

We can copy the information directly from "struct pvclock_vcpu_time_info",
remove pvclock_shadow_time.

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

diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 12e47e2..d59e606 100644 (file)
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -19,21 +19,6 @@
 #include <linux/percpu.h>
 #include <asm/pvclock.h>
 
-/*
- * These are perodically updated
- *    xen: magic shared_info page
- *    kvm: gpa registered via msr
- * and then copied here.
- */
-struct pvclock_shadow_time {
-       u64 tsc_timestamp;     /* TSC at last update of time vals.  */
-       u64 system_timestamp;  /* Time, in nanosecs, since boot.    */
-       u32 tsc_to_nsec_mul;
-       int tsc_shift;
-       u32 version;
-       u8  flags;
-};
-
 static u8 valid_flags __read_mostly = 0;
 
 void pvclock_set_flags(u8 flags)
@@ -41,32 +26,11 @@ void pvclock_set_flags(u8 flags)
        valid_flags = flags;
 }
 
-static u64 pvclock_get_nsec_offset(struct pvclock_shadow_time *shadow)
-{
-       u64 delta = native_read_tsc() - shadow->tsc_timestamp;
-       return pvclock_scale_delta(delta, shadow->tsc_to_nsec_mul,
-                                  shadow->tsc_shift);
-}
-
-/*
- * Reads a consistent set of time-base values from hypervisor,
- * into a shadow data area.
- */
-static unsigned pvclock_get_time_values(struct pvclock_shadow_time *dst,
-                                       struct pvclock_vcpu_time_info *src)
+static u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
 {
-       do {
-               dst->version = src->version;
-               rmb();          /* fetch version before data */
-               dst->tsc_timestamp     = src->tsc_timestamp;
-               dst->system_timestamp  = src->system_time;
-               dst->tsc_to_nsec_mul   = src->tsc_to_system_mul;
-               dst->tsc_shift         = src->tsc_shift;
-               dst->flags             = src->flags;
-               rmb();          /* test version after fetching data */
-       } while ((src->version & 1) || (dst->version != src->version));
-
-       return dst->version;
+       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)
@@ -90,21 +54,22 @@ void pvclock_resume(void)
 
 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
 {
-       struct pvclock_shadow_time shadow;
        unsigned version;
        cycle_t ret, offset;
        u64 last;
+       u8 flags;
 
        do {
-               version = pvclock_get_time_values(&shadow, src);
+               version = src->version;
                rdtsc_barrier();
-               offset = pvclock_get_nsec_offset(&shadow);
-               ret = shadow.system_timestamp + offset;
+               offset = pvclock_get_nsec_offset(src);
+               ret = src->system_time + offset;
+               flags = src->flags;
                rdtsc_barrier();
-       } while (version != src->version);
+       } while ((src->version & 1) || version != src->version);
 
        if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&
-               (shadow.flags & PVCLOCK_TSC_STABLE_BIT))
+               (flags & PVCLOCK_TSC_STABLE_BIT))
                return ret;
 
        /*