Originally from Jeremy Fitzhardinge.
We can copy the information directly from struct pvclock_vcpu_time_info,
remove pvclock_shadow_time.
Signed-off-by: Marcelo Tosatti mtosa...@redhat.com
Index: vsyscall/arch/x86/kernel/pvclock.c
===
--- vsyscall.orig/arch/x86/kernel/pvclock.c
+++ vsyscall/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)
+static u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
{
- 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)
-{
- 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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