[PATCH] vmi: cpu cycles fix

In order to share the common code in tsc.c which does CPU Khz calibration, we
need to make an accurate value of CPU speed available to the tsc.c code.  This
value loses a lot of precision in a VM because of the timing differences with
real hardware, but we need it to be as precise as possible so the guest can
make accurate time calculations with the cycle counters.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 17 insertions, 2 deletions

diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index 31bbe70d1e02..8352394d5efb 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -522,6 +522,7 @@ struct paravirt_ops paravirt_ops = {
         .read_tsc = native_read_tsc,
         .read_pmc = native_read_pmc,
         .get_scheduled_cycles = native_read_tsc,
+        .get_cpu_khz = native_calculate_cpu_khz,
         .load_tr_desc = native_load_tr_desc,
         .set_ldt = native_set_ldt,
         .load_gdt = native_load_gdt,
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index c9c9d54c91f6..59222a04234b 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -117,7 +117,7 @@ unsigned long long sched_clock(void)
         return cycles_2_ns(this_offset);
 }
 
-static unsigned long calculate_cpu_khz(void)
+unsigned long native_calculate_cpu_khz(void)
 {
         unsigned long long start, end;
         unsigned long count;
diff --git a/arch/i386/kernel/vmi.c b/arch/i386/kernel/vmi.c
index 556b9a6b7365..acdfe69fb7ad 100644
--- a/arch/i386/kernel/vmi.c
+++ b/arch/i386/kernel/vmi.c
@@ -874,6 +874,7 @@ static inline int __init activate_vmi(void)
                 paravirt_ops.setup_secondary_clock = vmi_timer_setup_secondary_alarm;
 #endif
                 paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles;
+                paravirt_ops.get_cpu_khz = vmi_cpu_khz;
         }
         if (!disable_noidle)
                 para_fill(safe_halt, Halt);
diff --git a/arch/i386/kernel/vmitime.c b/arch/i386/kernel/vmitime.c
index f2aa8fab8c02..4bb218e2eb14 100644
--- a/arch/i386/kernel/vmitime.c
+++ b/arch/i386/kernel/vmitime.c
@@ -177,6 +177,15 @@ unsigned long long vmi_get_sched_cycles(void)
         return read_available_cycles();
 }
 
+unsigned long vmi_cpu_khz(void)
+{
+        unsigned long long khz;
+
+        khz = vmi_timer_ops.get_cycle_frequency();
+        (void)do_div(khz, 1000);
+        return khz;
+}
+
 void __init vmi_time_init(void)
 {
         unsigned long long cycles_per_sec, cycles_per_msec;
@@ -206,7 +215,6 @@ void __init vmi_time_init(void)
         (void)do_div(cycles_per_alarm, alarm_hz);
         cycles_per_msec = cycles_per_sec;
         (void)do_div(cycles_per_msec, 1000);
-        cpu_khz = cycles_per_msec;
 
         printk(KERN_WARNING "VMI timer cycles/sec = %llu ; cycles/jiffy = %llu ;"
                "cycles/alarm = %llu\n", cycles_per_sec, cycles_per_jiffy,
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index a13230254f4f..a35c81480654 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -95,6 +95,7 @@ struct paravirt_ops
         u64 (*read_tsc)(void);
         u64 (*read_pmc)(void);
         u64 (*get_scheduled_cycles)(void);
+        unsigned long (*get_cpu_khz)(void);
 
         void (*load_tr_desc)(void);
         void (*load_gdt)(const struct Xgt_desc_struct *);
@@ -275,6 +276,7 @@ static inline void halt(void)
 #define rdtscll(val) (val = paravirt_ops.read_tsc())
 
 #define get_scheduled_cycles(val) (val = paravirt_ops.get_scheduled_cycles())
+#define calculate_cpu_khz() (paravirt_ops.get_cpu_khz())
 
 #define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
 
diff --git a/include/asm-i386/timer.h b/include/asm-i386/timer.h
index d1f7b4f575b4..12dd67bf760f 100644
--- a/include/asm-i386/timer.h
+++ b/include/asm-i386/timer.h
@@ -7,6 +7,7 @@
 
 void setup_pit_timer(void);
 unsigned long long native_sched_clock(void);
+unsigned long native_calculate_cpu_khz(void);
 
 /* Modifiers for buggy PIT handling */
 extern int pit_latch_buggy;
@@ -17,6 +18,7 @@ extern int recalibrate_cpu_khz(void);
 
 #ifndef CONFIG_PARAVIRT
 #define get_scheduled_cycles(val) rdtscll(val)
+#define calculate_cpu_khz() native_calculate_cpu_khz()
 #endif
 
 #endif
diff --git a/include/asm-i386/vmi_time.h b/include/asm-i386/vmi_time.h
index f59c35d37352..1f971eb7f71e 100644
--- a/include/asm-i386/vmi_time.h
+++ b/include/asm-i386/vmi_time.h
@@ -50,6 +50,7 @@ extern void __init vmi_time_init(void);
 extern unsigned long vmi_get_wallclock(void);
 extern int vmi_set_wallclock(unsigned long now);
 extern unsigned long long vmi_get_sched_cycles(void);
+extern unsigned long vmi_cpu_khz(void);
 
 #ifdef CONFIG_X86_LOCAL_APIC
 extern void __init vmi_timer_setup_boot_alarm(void);