From 42b5637d6989f75a7a0e8ea8633583564ff443ff Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Tue, 27 Nov 2012 23:28:50 -0200
Subject: [PATCH] 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>
---
arch/x86/kernel/pvclock.c | 57 ++++++++-------------------------------
1 file changed, 11 insertions(+), 46 deletions(-)
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 12e47e2104910..d59e606617944 100644
--- 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;
/*
--
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