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yaml --- r: 98431 b: refs/heads/master c: 035cfc6 h: refs/heads/master i: 98429: 26c8a72 98427: 06dc241 98423: fd65a86 98415: fec1b92 98399: 7abdc7e 98367: 02581e5 98303: 8d3fd52 v: v3
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Linus Torvalds
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Jun 25, 2008
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,2 +1,2 @@ | ||
| --- | ||
| refs/heads/master: 5af4e7a0bea715f2dd7190859a43eb2258b1f388 | ||
| refs/heads/master: 035cfc61a523343fe0bee5ec54348e26f330a06c |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,141 @@ | ||
| /* paravirtual clock -- common code used by kvm/xen | ||
| This program is free software; you can redistribute it and/or modify | ||
| it under the terms of the GNU General Public License as published by | ||
| the Free Software Foundation; either version 2 of the License, or | ||
| (at your option) any later version. | ||
| This program is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| GNU General Public License for more details. | ||
| You should have received a copy of the GNU General Public License | ||
| along with this program; if not, write to the Free Software | ||
| Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | ||
| */ | ||
|
|
||
| #include <linux/kernel.h> | ||
| #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; | ||
| }; | ||
|
|
||
| /* | ||
| * 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 | ||
|
|
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| return product; | ||
| } | ||
|
|
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| static u64 pvclock_get_nsec_offset(struct pvclock_shadow_time *shadow) | ||
| { | ||
| u64 delta = native_read_tsc() - shadow->tsc_timestamp; | ||
| return 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; | ||
| rmb(); /* test version after fetching data */ | ||
| } while ((src->version & 1) || (dst->version != src->version)); | ||
|
|
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| return dst->version; | ||
| } | ||
|
|
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| cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) | ||
| { | ||
| struct pvclock_shadow_time shadow; | ||
| unsigned version; | ||
| cycle_t ret, offset; | ||
|
|
||
| do { | ||
| version = pvclock_get_time_values(&shadow, src); | ||
| barrier(); | ||
| offset = pvclock_get_nsec_offset(&shadow); | ||
| ret = shadow.system_timestamp + offset; | ||
| barrier(); | ||
| } while (version != src->version); | ||
|
|
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| return ret; | ||
| } | ||
|
|
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| void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock, | ||
| struct pvclock_vcpu_time_info *vcpu_time, | ||
| struct timespec *ts) | ||
| { | ||
| u32 version; | ||
| u64 delta; | ||
| struct timespec now; | ||
|
|
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| /* get wallclock at system boot */ | ||
| do { | ||
| version = wall_clock->version; | ||
| rmb(); /* fetch version before time */ | ||
| now.tv_sec = wall_clock->sec; | ||
| now.tv_nsec = wall_clock->nsec; | ||
| rmb(); /* fetch time before checking version */ | ||
| } while ((wall_clock->version & 1) || (version != wall_clock->version)); | ||
|
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| delta = pvclock_clocksource_read(vcpu_time); /* time since system boot */ | ||
| delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec; | ||
|
|
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| now.tv_nsec = do_div(delta, NSEC_PER_SEC); | ||
| now.tv_sec = delta; | ||
|
|
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| set_normalized_timespec(ts, now.tv_sec, now.tv_nsec); | ||
| } |
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