169 lines
4.6 KiB
C
169 lines
4.6 KiB
C
/* KVM paravirtual clock driver. A clocksource implementation
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Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <linux/clocksource.h>
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#include <linux/kvm_para.h>
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#include <asm/pvclock.h>
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#include <asm/arch_hooks.h>
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#include <asm/msr.h>
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#include <asm/apic.h>
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#include <linux/percpu.h>
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#include <asm/reboot.h>
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#define KVM_SCALE 22
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static int kvmclock = 1;
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static int parse_no_kvmclock(char *arg)
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{
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kvmclock = 0;
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return 0;
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}
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early_param("no-kvmclock", parse_no_kvmclock);
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/* The hypervisor will put information about time periodically here */
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock);
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static struct pvclock_wall_clock wall_clock;
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/*
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* The wallclock is the time of day when we booted. Since then, some time may
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* have elapsed since the hypervisor wrote the data. So we try to account for
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* that with system time
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*/
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static unsigned long kvm_get_wallclock(void)
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{
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struct pvclock_vcpu_time_info *vcpu_time;
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struct timespec ts;
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int low, high;
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low = (int)__pa(&wall_clock);
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high = ((u64)__pa(&wall_clock) >> 32);
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native_write_msr(MSR_KVM_WALL_CLOCK, low, high);
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vcpu_time = &get_cpu_var(hv_clock);
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pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
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put_cpu_var(hv_clock);
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return ts.tv_sec;
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}
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static int kvm_set_wallclock(unsigned long now)
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{
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return -1;
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}
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static cycle_t kvm_clock_read(void)
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{
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struct pvclock_vcpu_time_info *src;
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cycle_t ret;
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src = &get_cpu_var(hv_clock);
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ret = pvclock_clocksource_read(src);
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put_cpu_var(hv_clock);
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return ret;
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}
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static struct clocksource kvm_clock = {
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.name = "kvm-clock",
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.read = kvm_clock_read,
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.rating = 400,
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.mask = CLOCKSOURCE_MASK(64),
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.mult = 1 << KVM_SCALE,
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.shift = KVM_SCALE,
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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static int kvm_register_clock(char *txt)
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{
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int cpu = smp_processor_id();
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int low, high;
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low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1;
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high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32);
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printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
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cpu, high, low, txt);
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return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high);
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}
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#ifdef CONFIG_X86_LOCAL_APIC
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static void kvm_setup_secondary_clock(void)
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{
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/*
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* Now that the first cpu already had this clocksource initialized,
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* we shouldn't fail.
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*/
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WARN_ON(kvm_register_clock("secondary cpu clock"));
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/* ok, done with our trickery, call native */
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setup_secondary_APIC_clock();
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}
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#endif
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#ifdef CONFIG_SMP
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static void __init kvm_smp_prepare_boot_cpu(void)
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{
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WARN_ON(kvm_register_clock("primary cpu clock"));
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native_smp_prepare_boot_cpu();
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}
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#endif
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/*
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* After the clock is registered, the host will keep writing to the
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* registered memory location. If the guest happens to shutdown, this memory
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* won't be valid. In cases like kexec, in which you install a new kernel, this
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* means a random memory location will be kept being written. So before any
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* kind of shutdown from our side, we unregister the clock by writting anything
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* that does not have the 'enable' bit set in the msr
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*/
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#ifdef CONFIG_KEXEC
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static void kvm_crash_shutdown(struct pt_regs *regs)
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{
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native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0);
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native_machine_crash_shutdown(regs);
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}
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#endif
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static void kvm_shutdown(void)
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{
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native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0);
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native_machine_shutdown();
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}
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void __init kvmclock_init(void)
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{
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if (!kvm_para_available())
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return;
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if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) {
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if (kvm_register_clock("boot clock"))
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return;
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pv_time_ops.get_wallclock = kvm_get_wallclock;
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pv_time_ops.set_wallclock = kvm_set_wallclock;
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pv_time_ops.sched_clock = kvm_clock_read;
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#ifdef CONFIG_X86_LOCAL_APIC
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pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock;
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#endif
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#ifdef CONFIG_SMP
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smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
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#endif
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machine_ops.shutdown = kvm_shutdown;
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#ifdef CONFIG_KEXEC
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machine_ops.crash_shutdown = kvm_crash_shutdown;
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#endif
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clocksource_register(&kvm_clock);
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}
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}
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