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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 | /* KVM paravirtual clock driver. A clocksource implementation Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc. 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/clocksource.h> #include <linux/kvm_para.h> #include <asm/pvclock.h> #include <asm/msr.h> #include <asm/apic.h> #include <linux/percpu.h> #include <asm/x86_init.h> #include <asm/reboot.h> #define KVM_SCALE 22 static int kvmclock = 1; static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; static int parse_no_kvmclock(char *arg) { kvmclock = 0; return 0; } early_param("no-kvmclock", parse_no_kvmclock); /* The hypervisor will put information about time periodically here */ static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock); static struct pvclock_wall_clock wall_clock; /* * The wallclock is the time of day when we booted. Since then, some time may * have elapsed since the hypervisor wrote the data. So we try to account for * that with system time */ static unsigned long kvm_get_wallclock(void) { struct pvclock_vcpu_time_info *vcpu_time; struct timespec ts; int low, high; low = (int)__pa_symbol(&wall_clock); high = ((u64)__pa_symbol(&wall_clock) >> 32); native_write_msr(msr_kvm_wall_clock, low, high); vcpu_time = &get_cpu_var(hv_clock); pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); put_cpu_var(hv_clock); return ts.tv_sec; } static int kvm_set_wallclock(unsigned long now) { return -1; } static cycle_t kvm_clock_read(void) { struct pvclock_vcpu_time_info *src; cycle_t ret; src = &get_cpu_var(hv_clock); ret = pvclock_clocksource_read(src); put_cpu_var(hv_clock); return ret; } static cycle_t kvm_clock_get_cycles(struct clocksource *cs) { return kvm_clock_read(); } /* * If we don't do that, there is the possibility that the guest * will calibrate under heavy load - thus, getting a lower lpj - * and execute the delays themselves without load. This is wrong, * because no delay loop can finish beforehand. * Any heuristics is subject to fail, because ultimately, a large * poll of guests can be running and trouble each other. So we preset * lpj here */ static unsigned long kvm_get_tsc_khz(void) { struct pvclock_vcpu_time_info *src; src = &per_cpu(hv_clock, 0); return pvclock_tsc_khz(src); } static void kvm_get_preset_lpj(void) { unsigned long khz; u64 lpj; khz = kvm_get_tsc_khz(); lpj = ((u64)khz * 1000); do_div(lpj, HZ); preset_lpj = lpj; } static struct clocksource kvm_clock = { .name = "kvm-clock", .read = kvm_clock_get_cycles, .rating = 400, .mask = CLOCKSOURCE_MASK(64), .mult = 1 << KVM_SCALE, .shift = KVM_SCALE, .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; int kvm_register_clock(char *txt) { int cpu = smp_processor_id(); int low, high, ret; low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); ret = native_write_msr_safe(msr_kvm_system_time, low, high); printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", cpu, high, low, txt); return ret; } #ifdef CONFIG_X86_LOCAL_APIC static void __cpuinit kvm_setup_secondary_clock(void) { /* * Now that the first cpu already had this clocksource initialized, * we shouldn't fail. */ WARN_ON(kvm_register_clock("secondary cpu clock")); /* ok, done with our trickery, call native */ setup_secondary_APIC_clock(); } #endif /* * After the clock is registered, the host will keep writing to the * registered memory location. If the guest happens to shutdown, this memory * won't be valid. In cases like kexec, in which you install a new kernel, this * means a random memory location will be kept being written. So before any * kind of shutdown from our side, we unregister the clock by writting anything * that does not have the 'enable' bit set in the msr */ #ifdef CONFIG_KEXEC static void kvm_crash_shutdown(struct pt_regs *regs) { native_write_msr(msr_kvm_system_time, 0, 0); native_machine_crash_shutdown(regs); } #endif static void kvm_shutdown(void) { native_write_msr(msr_kvm_system_time, 0, 0); native_machine_shutdown(); } void __init kvmclock_init(void) { if (!kvm_para_available()) return; if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE))) return; printk(KERN_INFO "kvm-clock: Using msrs %x and %x", msr_kvm_system_time, msr_kvm_wall_clock); if (kvm_register_clock("boot clock")) return; pv_time_ops.sched_clock = kvm_clock_read; x86_platform.calibrate_tsc = kvm_get_tsc_khz; x86_platform.get_wallclock = kvm_get_wallclock; x86_platform.set_wallclock = kvm_set_wallclock; #ifdef CONFIG_X86_LOCAL_APIC x86_cpuinit.setup_percpu_clockev = kvm_setup_secondary_clock; #endif machine_ops.shutdown = kvm_shutdown; #ifdef CONFIG_KEXEC machine_ops.crash_shutdown = kvm_crash_shutdown; #endif kvm_get_preset_lpj(); clocksource_register(&kvm_clock); pv_info.paravirt_enabled = 1; pv_info.name = "KVM"; if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); } |