| /* 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 <linux/hardirq.h> |
| #include <linux/memblock.h> |
| #include <linux/sched.h> |
| |
| #include <asm/x86_init.h> |
| #include <asm/reboot.h> |
| |
| 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 cycle_t kvm_sched_clock_offset; |
| |
| 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 struct pvclock_vsyscall_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 void kvm_get_wallclock(struct timespec *now) |
| { |
| struct pvclock_vcpu_time_info *vcpu_time; |
| int low, high; |
| int cpu; |
| |
| low = (int)__pa_symbol(&wall_clock); |
| high = ((u64)__pa_symbol(&wall_clock) >> 32); |
| |
| native_write_msr(msr_kvm_wall_clock, low, high); |
| |
| cpu = get_cpu(); |
| |
| vcpu_time = &hv_clock[cpu].pvti; |
| pvclock_read_wallclock(&wall_clock, vcpu_time, now); |
| |
| put_cpu(); |
| } |
| |
| static int kvm_set_wallclock(const struct timespec *now) |
| { |
| return -1; |
| } |
| |
| static cycle_t kvm_clock_read(void) |
| { |
| struct pvclock_vcpu_time_info *src; |
| cycle_t ret; |
| int cpu; |
| |
| preempt_disable_notrace(); |
| cpu = smp_processor_id(); |
| src = &hv_clock[cpu].pvti; |
| ret = pvclock_clocksource_read(src); |
| preempt_enable_notrace(); |
| return ret; |
| } |
| |
| static cycle_t kvm_clock_get_cycles(struct clocksource *cs) |
| { |
| return kvm_clock_read(); |
| } |
| |
| static cycle_t kvm_sched_clock_read(void) |
| { |
| return kvm_clock_read() - kvm_sched_clock_offset; |
| } |
| |
| static inline void kvm_sched_clock_init(bool stable) |
| { |
| if (!stable) { |
| pv_time_ops.sched_clock = kvm_clock_read; |
| return; |
| } |
| |
| kvm_sched_clock_offset = kvm_clock_read(); |
| pv_time_ops.sched_clock = kvm_sched_clock_read; |
| set_sched_clock_stable(); |
| |
| printk(KERN_INFO "kvm-clock: using sched offset of %llu cycles\n", |
| kvm_sched_clock_offset); |
| |
| BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) > |
| sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time)); |
| } |
| |
| /* |
| * 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; |
| int cpu; |
| unsigned long tsc_khz; |
| |
| cpu = get_cpu(); |
| src = &hv_clock[cpu].pvti; |
| tsc_khz = pvclock_tsc_khz(src); |
| put_cpu(); |
| return tsc_khz; |
| } |
| |
| 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; |
| } |
| |
| bool kvm_check_and_clear_guest_paused(void) |
| { |
| bool ret = false; |
| struct pvclock_vcpu_time_info *src; |
| int cpu = smp_processor_id(); |
| |
| if (!hv_clock) |
| return ret; |
| |
| src = &hv_clock[cpu].pvti; |
| if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) { |
| src->flags &= ~PVCLOCK_GUEST_STOPPED; |
| pvclock_touch_watchdogs(); |
| ret = true; |
| } |
| |
| return ret; |
| } |
| |
| static struct clocksource kvm_clock = { |
| .name = "kvm-clock", |
| .read = kvm_clock_get_cycles, |
| .rating = 400, |
| .mask = CLOCKSOURCE_MASK(64), |
| .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| }; |
| |
| int kvm_register_clock(char *txt) |
| { |
| int cpu = smp_processor_id(); |
| int low, high, ret; |
| struct pvclock_vcpu_time_info *src; |
| |
| if (!hv_clock) |
| return 0; |
| |
| src = &hv_clock[cpu].pvti; |
| low = (int)slow_virt_to_phys(src) | 1; |
| high = ((u64)slow_virt_to_phys(src) >> 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; |
| } |
| |
| static void kvm_save_sched_clock_state(void) |
| { |
| } |
| |
| static void kvm_restore_sched_clock_state(void) |
| { |
| kvm_register_clock("primary cpu clock, resume"); |
| } |
| |
| #ifdef CONFIG_X86_LOCAL_APIC |
| static void 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")); |
| } |
| #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_CORE |
| static void kvm_crash_shutdown(struct pt_regs *regs) |
| { |
| native_write_msr(msr_kvm_system_time, 0, 0); |
| kvm_disable_steal_time(); |
| native_machine_crash_shutdown(regs); |
| } |
| #endif |
| |
| static void kvm_shutdown(void) |
| { |
| native_write_msr(msr_kvm_system_time, 0, 0); |
| kvm_disable_steal_time(); |
| native_machine_shutdown(); |
| } |
| |
| void __init kvmclock_init(void) |
| { |
| struct pvclock_vcpu_time_info *vcpu_time; |
| unsigned long mem; |
| int size, cpu; |
| u8 flags; |
| |
| size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS); |
| |
| 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); |
| |
| mem = memblock_alloc(size, PAGE_SIZE); |
| if (!mem) |
| return; |
| hv_clock = __va(mem); |
| memset(hv_clock, 0, size); |
| |
| if (kvm_register_clock("primary cpu clock")) { |
| hv_clock = NULL; |
| memblock_free(mem, size); |
| return; |
| } |
| |
| if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) |
| pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); |
| |
| cpu = get_cpu(); |
| vcpu_time = &hv_clock[cpu].pvti; |
| flags = pvclock_read_flags(vcpu_time); |
| |
| kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); |
| put_cpu(); |
| |
| 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.early_percpu_clock_init = |
| kvm_setup_secondary_clock; |
| #endif |
| x86_platform.save_sched_clock_state = kvm_save_sched_clock_state; |
| x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state; |
| machine_ops.shutdown = kvm_shutdown; |
| #ifdef CONFIG_KEXEC_CORE |
| machine_ops.crash_shutdown = kvm_crash_shutdown; |
| #endif |
| kvm_get_preset_lpj(); |
| clocksource_register_hz(&kvm_clock, NSEC_PER_SEC); |
| pv_info.name = "KVM"; |
| } |
| |
| int __init kvm_setup_vsyscall_timeinfo(void) |
| { |
| #ifdef CONFIG_X86_64 |
| int cpu; |
| int ret; |
| u8 flags; |
| struct pvclock_vcpu_time_info *vcpu_time; |
| unsigned int size; |
| |
| if (!hv_clock) |
| return 0; |
| |
| size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS); |
| |
| cpu = get_cpu(); |
| |
| vcpu_time = &hv_clock[cpu].pvti; |
| flags = pvclock_read_flags(vcpu_time); |
| |
| if (!(flags & PVCLOCK_TSC_STABLE_BIT)) { |
| put_cpu(); |
| return 1; |
| } |
| |
| if ((ret = pvclock_init_vsyscall(hv_clock, size))) { |
| put_cpu(); |
| return ret; |
| } |
| |
| put_cpu(); |
| |
| kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK; |
| #endif |
| return 0; |
| } |