x86: Make xen use the paravirt clocksource structs and functions

This patch updates the xen guest to use the pvclock structs
and helper functions.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 13 insertions, 120 deletions

diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 2e641be2737e..3a4f16aea4bf 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -5,6 +5,7 @@
 config XEN
         bool "Xen guest support"
         select PARAVIRT
+        select PARAVIRT_CLOCK
         depends on X86_32
         depends on X86_CMPXCHG && X86_TSC && !(X86_VISWS || X86_VOYAGER)
         help
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 52b2e3856980..41e217503c96 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -14,6 +14,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/math64.h>
 
+#include <asm/pvclock.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 
@@ -31,17 +32,6 @@
 
 static cycle_t xen_clocksource_read(void);
 
-/* These are perodically updated in shared_info, and then copied here. */
-struct shadow_time_info {
-        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;
-};
-
-static DEFINE_PER_CPU(struct shadow_time_info, shadow_time);
-
 /* runstate info updated by Xen */
 static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
 
@@ -211,7 +201,7 @@ unsigned long long xen_sched_clock(void)
 unsigned long xen_cpu_khz(void)
 {
         u64 xen_khz = 1000000ULL << 32;
-        const struct vcpu_time_info *info =
+        const struct pvclock_vcpu_time_info *info =
                 &HYPERVISOR_shared_info->vcpu_info[0].time;
 
         do_div(xen_khz, info->tsc_to_system_mul);
@@ -223,121 +213,26 @@ unsigned long xen_cpu_khz(void)
         return xen_khz;
 }
 
-/*
- * Reads a consistent set of time-base values from Xen, into a shadow data
- * area.
- */
-static unsigned get_time_values_from_xen(void)
-{
-        struct vcpu_time_info   *src;
-        struct shadow_time_info *dst;
-
-        /* src is shared memory with the hypervisor, so we need to
-           make sure we get a consistent snapshot, even in the face of
-           being preempted. */
-        src = &__get_cpu_var(xen_vcpu)->time;
-        dst = &__get_cpu_var(shadow_time);
-
-        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;
-                rmb();          /* test version after fetching data */
-        } while ((src->version & 1) | (dst->version ^ src->version));
-
-        return dst->version;
-}
-
-/*
- * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
- * yielding a 64-bit result.
- */
-static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
-{
-        u64 product;
-#ifdef __i386__
-        u32 tmp1, tmp2;
-#endif
-
-        if (shift < 0)
-                delta >>= -shift;
-        else
-                delta <<= shift;
-
-#ifdef __i386__
-        __asm__ (
-                "mul  %5       ; "
-                "mov  %4,%%eax ; "
-                "mov  %%edx,%4 ; "
-                "mul  %5       ; "
-                "xor  %5,%5    ; "
-                "add  %4,%%eax ; "
-                "adc  %5,%%edx ; "
-                : "=A" (product), "=r" (tmp1), "=r" (tmp2)
-                : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
-#elif __x86_64__
-        __asm__ (
-                "mul %%rdx ; shrd $32,%%rdx,%%rax"
-                : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
-#else
-#error implement me!
-#endif
-
-        return product;
-}
-
-static u64 get_nsec_offset(struct shadow_time_info *shadow)
-{
-        u64 now, delta;
-        now = native_read_tsc();
-        delta = now - shadow->tsc_timestamp;
-        return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
-}
-
 static cycle_t xen_clocksource_read(void)
 {
-        struct shadow_time_info *shadow = &get_cpu_var(shadow_time);
+        struct pvclock_vcpu_time_info *src;
         cycle_t ret;
-        unsigned version;
-
-        do {
-                version = get_time_values_from_xen();
-                barrier();
-                ret = shadow->system_timestamp + get_nsec_offset(shadow);
-                barrier();
-        } while (version != __get_cpu_var(xen_vcpu)->time.version);
-
-        put_cpu_var(shadow_time);
 
+        src = &get_cpu_var(xen_vcpu)->time;
+        ret = pvclock_clocksource_read(src);
+        put_cpu_var(xen_vcpu);
         return ret;
 }
 
 static void xen_read_wallclock(struct timespec *ts)
 {
-        const struct shared_info *s = HYPERVISOR_shared_info;
-        u32 version;
-        u64 delta;
-        struct timespec now;
-
-        /* get wallclock at system boot */
-        do {
-                version = s->wc_version;
-                rmb();          /* fetch version before time */
-                now.tv_sec  = s->wc_sec;
-                now.tv_nsec = s->wc_nsec;
-                rmb();          /* fetch time before checking version */
-        } while ((s->wc_version & 1) | (version ^ s->wc_version));
+        struct shared_info *s = HYPERVISOR_shared_info;
+        struct pvclock_wall_clock *wall_clock = &(s->wc);
+        struct pvclock_vcpu_time_info *vcpu_time;
 
-        delta = xen_clocksource_read(); /* time since system boot */
-        delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec;
-
-        now.tv_nsec = do_div(delta, NSEC_PER_SEC);
-        now.tv_sec = delta;
-
-        set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
+        vcpu_time = &get_cpu_var(xen_vcpu)->time;
+        pvclock_read_wallclock(wall_clock, vcpu_time, ts);
+        put_cpu_var(xen_vcpu);
 }
 
 unsigned long xen_get_wallclock(void)
@@ -345,7 +240,6 @@ unsigned long xen_get_wallclock(void)
         struct timespec ts;
 
         xen_read_wallclock(&ts);
-
         return ts.tv_sec;
 }
 
@@ -569,8 +463,6 @@ __init void xen_time_init(void)
 {
         int cpu = smp_processor_id();
 
-        get_time_values_from_xen();
-
         clocksource_register(&xen_clocksource);
 
         if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) {