diff options
Diffstat (limited to 'arch/x86/kernel/kvmclock.c')
| -rw-r--r-- | arch/x86/kernel/kvmclock.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c new file mode 100644 index 000000000000..87edf1ceb1df --- /dev/null +++ b/arch/x86/kernel/kvmclock.c @@ -0,0 +1,168 @@ +/* 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/arch_hooks.h> +#include <asm/msr.h> +#include <asm/apic.h> +#include <linux/percpu.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 struct clocksource kvm_clock = { + .name = "kvm-clock", + .read = kvm_clock_read, + .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 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 +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; +#ifdef CONFIG_X86_LOCAL_APIC + pv_apic_ops.setup_secondary_clock = 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 + clocksource_register(&kvm_clock); + } +} |