| /* 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 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(&wall_clock); |
| high = ((u64)__pa(&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, |
| }; |
| |
| static int kvm_register_clock(char *txt) |
| { |
| int cpu = smp_processor_id(); |
| int low, high; |
| low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; |
| high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); |
| printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", |
| cpu, high, low, txt); |
| return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high); |
| } |
| |
| #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 |
| |
| #ifdef CONFIG_SMP |
| static void __init kvm_smp_prepare_boot_cpu(void) |
| { |
| WARN_ON(kvm_register_clock("primary cpu clock")); |
| native_smp_prepare_boot_cpu(); |
| } |
| #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_safe(MSR_KVM_SYSTEM_TIME, 0, 0); |
| native_machine_crash_shutdown(regs); |
| } |
| #endif |
| |
| static void kvm_shutdown(void) |
| { |
| native_write_msr_safe(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_CLOCKSOURCE)) { |
| if (kvm_register_clock("boot clock")) |
| return; |
| pv_time_ops.get_wallclock = kvm_get_wallclock; |
| pv_time_ops.set_wallclock = kvm_set_wallclock; |
| pv_time_ops.sched_clock = kvm_clock_read; |
| pv_time_ops.get_tsc_khz = kvm_get_tsc_khz; |
| #ifdef CONFIG_X86_LOCAL_APIC |
| x86_cpuinit.setup_percpu_clockev = |
| kvm_setup_secondary_clock; |
| #endif |
| #ifdef CONFIG_SMP |
| smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; |
| #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"; |
| } |
| } |