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authorIngo Molnar <mingo@elte.hu>2008-06-25 06:16:51 -0400
committerIngo Molnar <mingo@elte.hu>2008-06-25 06:16:51 -0400
commitd02859ecb321c8c0f74cb9bbe3f51a59e58822b0 (patch)
tree05dd5bdc55081c0a90bf0afc35c07d0d6e25d015 /arch/x86/xen/time.c
parenta987b16cc6123af2c9414032701bab5f73c54c89 (diff)
parent543cf4cb3fe6f6cae3651ba918b9c56200b257d0 (diff)
Merge commit 'v2.6.26-rc8' into x86/xen
Conflicts: arch/x86/xen/enlighten.c arch/x86/xen/mmu.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/xen/time.c')
-rw-r--r--arch/x86/xen/time.c132
1 files changed, 12 insertions, 120 deletions
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 0da249dbdc49..64f0038b9558 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -14,6 +14,7 @@
14#include <linux/kernel_stat.h> 14#include <linux/kernel_stat.h>
15#include <linux/math64.h> 15#include <linux/math64.h>
16 16
17#include <asm/pvclock.h>
17#include <asm/xen/hypervisor.h> 18#include <asm/xen/hypervisor.h>
18#include <asm/xen/hypercall.h> 19#include <asm/xen/hypercall.h>
19 20
@@ -31,17 +32,6 @@
31 32
32static cycle_t xen_clocksource_read(void); 33static cycle_t xen_clocksource_read(void);
33 34
34/* These are perodically updated in shared_info, and then copied here. */
35struct shadow_time_info {
36 u64 tsc_timestamp; /* TSC at last update of time vals. */
37 u64 system_timestamp; /* Time, in nanosecs, since boot. */
38 u32 tsc_to_nsec_mul;
39 int tsc_shift;
40 u32 version;
41};
42
43static DEFINE_PER_CPU(struct shadow_time_info, shadow_time);
44
45/* runstate info updated by Xen */ 35/* runstate info updated by Xen */
46static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate); 36static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
47 37
@@ -211,7 +201,7 @@ unsigned long long xen_sched_clock(void)
211unsigned long xen_cpu_khz(void) 201unsigned long xen_cpu_khz(void)
212{ 202{
213 u64 xen_khz = 1000000ULL << 32; 203 u64 xen_khz = 1000000ULL << 32;
214 const struct vcpu_time_info *info = 204 const struct pvclock_vcpu_time_info *info =
215 &HYPERVISOR_shared_info->vcpu_info[0].time; 205 &HYPERVISOR_shared_info->vcpu_info[0].time;
216 206
217 do_div(xen_khz, info->tsc_to_system_mul); 207 do_div(xen_khz, info->tsc_to_system_mul);
@@ -223,121 +213,26 @@ unsigned long xen_cpu_khz(void)
223 return xen_khz; 213 return xen_khz;
224} 214}
225 215
226/*
227 * Reads a consistent set of time-base values from Xen, into a shadow data
228 * area.
229 */
230static unsigned get_time_values_from_xen(void)
231{
232 struct vcpu_time_info *src;
233 struct shadow_time_info *dst;
234
235 /* src is shared memory with the hypervisor, so we need to
236 make sure we get a consistent snapshot, even in the face of
237 being preempted. */
238 src = &__get_cpu_var(xen_vcpu)->time;
239 dst = &__get_cpu_var(shadow_time);
240
241 do {
242 dst->version = src->version;
243 rmb(); /* fetch version before data */
244 dst->tsc_timestamp = src->tsc_timestamp;
245 dst->system_timestamp = src->system_time;
246 dst->tsc_to_nsec_mul = src->tsc_to_system_mul;
247 dst->tsc_shift = src->tsc_shift;
248 rmb(); /* test version after fetching data */
249 } while ((src->version & 1) | (dst->version ^ src->version));
250
251 return dst->version;
252}
253
254/*
255 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
256 * yielding a 64-bit result.
257 */
258static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
259{
260 u64 product;
261#ifdef __i386__
262 u32 tmp1, tmp2;
263#endif
264
265 if (shift < 0)
266 delta >>= -shift;
267 else
268 delta <<= shift;
269
270#ifdef __i386__
271 __asm__ (
272 "mul %5 ; "
273 "mov %4,%%eax ; "
274 "mov %%edx,%4 ; "
275 "mul %5 ; "
276 "xor %5,%5 ; "
277 "add %4,%%eax ; "
278 "adc %5,%%edx ; "
279 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
280 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
281#elif __x86_64__
282 __asm__ (
283 "mul %%rdx ; shrd $32,%%rdx,%%rax"
284 : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
285#else
286#error implement me!
287#endif
288
289 return product;
290}
291
292static u64 get_nsec_offset(struct shadow_time_info *shadow)
293{
294 u64 now, delta;
295 now = native_read_tsc();
296 delta = now - shadow->tsc_timestamp;
297 return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
298}
299
300static cycle_t xen_clocksource_read(void) 216static cycle_t xen_clocksource_read(void)
301{ 217{
302 struct shadow_time_info *shadow = &get_cpu_var(shadow_time); 218 struct pvclock_vcpu_time_info *src;
303 cycle_t ret; 219 cycle_t ret;
304 unsigned version;
305
306 do {
307 version = get_time_values_from_xen();
308 barrier();
309 ret = shadow->system_timestamp + get_nsec_offset(shadow);
310 barrier();
311 } while (version != __get_cpu_var(xen_vcpu)->time.version);
312
313 put_cpu_var(shadow_time);
314 220
221 src = &get_cpu_var(xen_vcpu)->time;
222 ret = pvclock_clocksource_read(src);
223 put_cpu_var(xen_vcpu);
315 return ret; 224 return ret;
316} 225}
317 226
318static void xen_read_wallclock(struct timespec *ts) 227static void xen_read_wallclock(struct timespec *ts)
319{ 228{
320 const struct shared_info *s = HYPERVISOR_shared_info; 229 struct shared_info *s = HYPERVISOR_shared_info;
321 u32 version; 230 struct pvclock_wall_clock *wall_clock = &(s->wc);
322 u64 delta; 231 struct pvclock_vcpu_time_info *vcpu_time;
323 struct timespec now;
324
325 /* get wallclock at system boot */
326 do {
327 version = s->wc_version;
328 rmb(); /* fetch version before time */
329 now.tv_sec = s->wc_sec;
330 now.tv_nsec = s->wc_nsec;
331 rmb(); /* fetch time before checking version */
332 } while ((s->wc_version & 1) | (version ^ s->wc_version));
333 232
334 delta = xen_clocksource_read(); /* time since system boot */ 233 vcpu_time = &get_cpu_var(xen_vcpu)->time;
335 delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec; 234 pvclock_read_wallclock(wall_clock, vcpu_time, ts);
336 235 put_cpu_var(xen_vcpu);
337 now.tv_nsec = do_div(delta, NSEC_PER_SEC);
338 now.tv_sec = delta;
339
340 set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
341} 236}
342 237
343unsigned long xen_get_wallclock(void) 238unsigned long xen_get_wallclock(void)
@@ -345,7 +240,6 @@ unsigned long xen_get_wallclock(void)
345 struct timespec ts; 240 struct timespec ts;
346 241
347 xen_read_wallclock(&ts); 242 xen_read_wallclock(&ts);
348
349 return ts.tv_sec; 243 return ts.tv_sec;
350} 244}
351 245
@@ -582,8 +476,6 @@ __init void xen_time_init(void)
582{ 476{
583 int cpu = smp_processor_id(); 477 int cpu = smp_processor_id();
584 478
585 get_time_values_from_xen();
586
587 clocksource_register(&xen_clocksource); 479 clocksource_register(&xen_clocksource);
588 480
589 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) { 481 if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) {