Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 1 | /* paravirtual clock -- common code used by kvm/xen |
| 2 | |
| 3 | This program is free software; you can redistribute it and/or modify |
| 4 | it under the terms of the GNU General Public License as published by |
| 5 | the Free Software Foundation; either version 2 of the License, or |
| 6 | (at your option) any later version. |
| 7 | |
| 8 | This program is distributed in the hope that it will be useful, |
| 9 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | GNU General Public License for more details. |
| 12 | |
| 13 | You should have received a copy of the GNU General Public License |
| 14 | along with this program; if not, write to the Free Software |
| 15 | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 16 | */ |
| 17 | |
| 18 | #include <linux/kernel.h> |
| 19 | #include <linux/percpu.h> |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 20 | #include <linux/notifier.h> |
| 21 | #include <linux/sched.h> |
| 22 | #include <linux/gfp.h> |
| 23 | #include <linux/bootmem.h> |
| 24 | #include <asm/fixmap.h> |
Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 25 | #include <asm/pvclock.h> |
| 26 | |
Glauber Costa | 424c32f | 2010-05-11 12:17:39 -0400 | [diff] [blame] | 27 | static u8 valid_flags __read_mostly = 0; |
| 28 | |
| 29 | void pvclock_set_flags(u8 flags) |
| 30 | { |
| 31 | valid_flags = flags; |
| 32 | } |
| 33 | |
Glauber Costa | 3807f34 | 2008-07-28 11:47:52 -0300 | [diff] [blame] | 34 | unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src) |
| 35 | { |
Harvey Harrison | a085460 | 2008-09-23 11:01:45 -0700 | [diff] [blame] | 36 | u64 pv_tsc_khz = 1000000ULL << 32; |
Glauber Costa | 3807f34 | 2008-07-28 11:47:52 -0300 | [diff] [blame] | 37 | |
Harvey Harrison | a085460 | 2008-09-23 11:01:45 -0700 | [diff] [blame] | 38 | do_div(pv_tsc_khz, src->tsc_to_system_mul); |
Glauber Costa | 3807f34 | 2008-07-28 11:47:52 -0300 | [diff] [blame] | 39 | if (src->tsc_shift < 0) |
Harvey Harrison | a085460 | 2008-09-23 11:01:45 -0700 | [diff] [blame] | 40 | pv_tsc_khz <<= -src->tsc_shift; |
Glauber Costa | 3807f34 | 2008-07-28 11:47:52 -0300 | [diff] [blame] | 41 | else |
Harvey Harrison | a085460 | 2008-09-23 11:01:45 -0700 | [diff] [blame] | 42 | pv_tsc_khz >>= src->tsc_shift; |
| 43 | return pv_tsc_khz; |
Glauber Costa | 3807f34 | 2008-07-28 11:47:52 -0300 | [diff] [blame] | 44 | } |
| 45 | |
Marcelo Tosatti | d63285e | 2013-10-11 21:39:25 -0300 | [diff] [blame] | 46 | void pvclock_touch_watchdogs(void) |
| 47 | { |
| 48 | touch_softlockup_watchdog_sync(); |
| 49 | clocksource_touch_watchdog(); |
| 50 | rcu_cpu_stall_reset(); |
Marcelo Tosatti | 8b41452 | 2013-10-11 21:39:26 -0300 | [diff] [blame] | 51 | reset_hung_task_detector(); |
Marcelo Tosatti | d63285e | 2013-10-11 21:39:25 -0300 | [diff] [blame] | 52 | } |
| 53 | |
Glauber Costa | 489fb49 | 2010-05-11 12:17:40 -0400 | [diff] [blame] | 54 | static atomic64_t last_value = ATOMIC64_INIT(0); |
| 55 | |
Jeremy Fitzhardinge | e7a3481 | 2010-10-25 16:53:46 -0700 | [diff] [blame] | 56 | void pvclock_resume(void) |
| 57 | { |
| 58 | atomic64_set(&last_value, 0); |
| 59 | } |
| 60 | |
Marcelo Tosatti | 2697902 | 2012-11-27 23:28:52 -0200 | [diff] [blame] | 61 | u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src) |
| 62 | { |
| 63 | unsigned version; |
| 64 | cycle_t ret; |
| 65 | u8 flags; |
| 66 | |
| 67 | do { |
| 68 | version = __pvclock_read_cycles(src, &ret, &flags); |
| 69 | } while ((src->version & 1) || version != src->version); |
| 70 | |
| 71 | return flags & valid_flags; |
| 72 | } |
| 73 | |
Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 74 | cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) |
| 75 | { |
Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 76 | unsigned version; |
Marcelo Tosatti | dce2db0 | 2012-11-27 23:28:51 -0200 | [diff] [blame] | 77 | cycle_t ret; |
Glauber Costa | 489fb49 | 2010-05-11 12:17:40 -0400 | [diff] [blame] | 78 | u64 last; |
Marcelo Tosatti | 42b5637 | 2012-11-27 23:28:50 -0200 | [diff] [blame] | 79 | u8 flags; |
Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 80 | |
| 81 | do { |
Marcelo Tosatti | dce2db0 | 2012-11-27 23:28:51 -0200 | [diff] [blame] | 82 | version = __pvclock_read_cycles(src, &ret, &flags); |
Marcelo Tosatti | 42b5637 | 2012-11-27 23:28:50 -0200 | [diff] [blame] | 83 | } while ((src->version & 1) || version != src->version); |
Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 84 | |
Marcelo Tosatti | d63285e | 2013-10-11 21:39:25 -0300 | [diff] [blame] | 85 | if (unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) { |
| 86 | src->flags &= ~PVCLOCK_GUEST_STOPPED; |
| 87 | pvclock_touch_watchdogs(); |
| 88 | } |
| 89 | |
Glauber Costa | 3a0d725 | 2010-05-11 12:17:45 -0400 | [diff] [blame] | 90 | if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) && |
Marcelo Tosatti | 42b5637 | 2012-11-27 23:28:50 -0200 | [diff] [blame] | 91 | (flags & PVCLOCK_TSC_STABLE_BIT)) |
Glauber Costa | 3a0d725 | 2010-05-11 12:17:45 -0400 | [diff] [blame] | 92 | return ret; |
| 93 | |
Glauber Costa | 489fb49 | 2010-05-11 12:17:40 -0400 | [diff] [blame] | 94 | /* |
| 95 | * Assumption here is that last_value, a global accumulator, always goes |
| 96 | * forward. If we are less than that, we should not be much smaller. |
| 97 | * We assume there is an error marging we're inside, and then the correction |
| 98 | * does not sacrifice accuracy. |
| 99 | * |
| 100 | * For reads: global may have changed between test and return, |
| 101 | * but this means someone else updated poked the clock at a later time. |
| 102 | * We just need to make sure we are not seeing a backwards event. |
| 103 | * |
| 104 | * For updates: last_value = ret is not enough, since two vcpus could be |
| 105 | * updating at the same time, and one of them could be slightly behind, |
| 106 | * making the assumption that last_value always go forward fail to hold. |
| 107 | */ |
| 108 | last = atomic64_read(&last_value); |
| 109 | do { |
| 110 | if (ret < last) |
| 111 | return last; |
| 112 | last = atomic64_cmpxchg(&last_value, last, ret); |
| 113 | } while (unlikely(last != ret)); |
| 114 | |
Gerd Hoffmann | 7af192c | 2008-06-03 16:17:29 +0200 | [diff] [blame] | 115 | return ret; |
| 116 | } |
| 117 | |
| 118 | void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock, |
| 119 | struct pvclock_vcpu_time_info *vcpu_time, |
| 120 | struct timespec *ts) |
| 121 | { |
| 122 | u32 version; |
| 123 | u64 delta; |
| 124 | struct timespec now; |
| 125 | |
| 126 | /* get wallclock at system boot */ |
| 127 | do { |
| 128 | version = wall_clock->version; |
| 129 | rmb(); /* fetch version before time */ |
| 130 | now.tv_sec = wall_clock->sec; |
| 131 | now.tv_nsec = wall_clock->nsec; |
| 132 | rmb(); /* fetch time before checking version */ |
| 133 | } while ((wall_clock->version & 1) || (version != wall_clock->version)); |
| 134 | |
| 135 | delta = pvclock_clocksource_read(vcpu_time); /* time since system boot */ |
| 136 | delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec; |
| 137 | |
| 138 | now.tv_nsec = do_div(delta, NSEC_PER_SEC); |
| 139 | now.tv_sec = delta; |
| 140 | |
| 141 | set_normalized_timespec(ts, now.tv_sec, now.tv_nsec); |
| 142 | } |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 143 | |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 144 | #ifdef CONFIG_X86_64 |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 145 | /* |
| 146 | * Initialize the generic pvclock vsyscall state. This will allocate |
| 147 | * a/some page(s) for the per-vcpu pvclock information, set up a |
| 148 | * fixmap mapping for the page(s) |
| 149 | */ |
| 150 | |
| 151 | int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i, |
| 152 | int size) |
| 153 | { |
| 154 | int idx; |
| 155 | |
| 156 | WARN_ON (size != PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE); |
| 157 | |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 158 | for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) { |
| 159 | __set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx, |
Peter Hurley | 3d2a80a | 2013-02-27 15:28:28 -0500 | [diff] [blame] | 160 | __pa(i) + (idx*PAGE_SIZE), |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 161 | PAGE_KERNEL_VVAR); |
| 162 | } |
| 163 | |
Marcelo Tosatti | 71056ae | 2012-11-27 23:28:55 -0200 | [diff] [blame] | 164 | return 0; |
| 165 | } |
| 166 | #endif |