339 lines
8.2 KiB
C
339 lines
8.2 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/msr.h>
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#include <asm/apic.h>
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#include <linux/percpu.h>
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#include <linux/hardirq.h>
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#include <linux/memblock.h>
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#include <linux/sched.h>
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#include <asm/x86_init.h>
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#include <asm/reboot.h>
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static int kvmclock __ro_after_init = 1;
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static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
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static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
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static u64 kvm_sched_clock_offset;
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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 struct pvclock_vsyscall_time_info *hv_clock;
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static struct pvclock_wall_clock wall_clock;
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struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
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{
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return hv_clock;
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}
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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 void kvm_get_wallclock(struct timespec *now)
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{
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struct pvclock_vcpu_time_info *vcpu_time;
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int low, high;
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int cpu;
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low = (int)__pa_symbol(&wall_clock);
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high = ((u64)__pa_symbol(&wall_clock) >> 32);
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native_write_msr(msr_kvm_wall_clock, low, high);
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cpu = get_cpu();
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vcpu_time = &hv_clock[cpu].pvti;
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pvclock_read_wallclock(&wall_clock, vcpu_time, now);
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put_cpu();
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}
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static int kvm_set_wallclock(const struct timespec *now)
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{
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return -1;
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}
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static u64 kvm_clock_read(void)
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{
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struct pvclock_vcpu_time_info *src;
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u64 ret;
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int cpu;
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preempt_disable_notrace();
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cpu = smp_processor_id();
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src = &hv_clock[cpu].pvti;
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ret = pvclock_clocksource_read(src);
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preempt_enable_notrace();
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return ret;
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}
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static u64 kvm_clock_get_cycles(struct clocksource *cs)
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{
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return kvm_clock_read();
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}
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static u64 kvm_sched_clock_read(void)
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{
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return kvm_clock_read() - kvm_sched_clock_offset;
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}
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static inline void kvm_sched_clock_init(bool stable)
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{
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if (!stable) {
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pv_time_ops.sched_clock = kvm_clock_read;
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return;
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}
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kvm_sched_clock_offset = kvm_clock_read();
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pv_time_ops.sched_clock = kvm_sched_clock_read;
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set_sched_clock_stable();
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printk(KERN_INFO "kvm-clock: using sched offset of %llu cycles\n",
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kvm_sched_clock_offset);
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BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) >
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sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time));
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}
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/*
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* If we don't do that, there is the possibility that the guest
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* will calibrate under heavy load - thus, getting a lower lpj -
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* and execute the delays themselves without load. This is wrong,
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* because no delay loop can finish beforehand.
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* Any heuristics is subject to fail, because ultimately, a large
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* poll of guests can be running and trouble each other. So we preset
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* lpj here
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*/
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static unsigned long kvm_get_tsc_khz(void)
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{
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struct pvclock_vcpu_time_info *src;
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int cpu;
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unsigned long tsc_khz;
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cpu = get_cpu();
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src = &hv_clock[cpu].pvti;
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tsc_khz = pvclock_tsc_khz(src);
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put_cpu();
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return tsc_khz;
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}
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static void kvm_get_preset_lpj(void)
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{
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unsigned long khz;
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u64 lpj;
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khz = kvm_get_tsc_khz();
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lpj = ((u64)khz * 1000);
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do_div(lpj, HZ);
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preset_lpj = lpj;
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}
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bool kvm_check_and_clear_guest_paused(void)
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{
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bool ret = false;
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struct pvclock_vcpu_time_info *src;
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int cpu = smp_processor_id();
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if (!hv_clock)
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return ret;
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src = &hv_clock[cpu].pvti;
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if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
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src->flags &= ~PVCLOCK_GUEST_STOPPED;
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pvclock_touch_watchdogs();
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ret = true;
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}
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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_get_cycles,
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.rating = 400,
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.mask = CLOCKSOURCE_MASK(64),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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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, ret;
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struct pvclock_vcpu_time_info *src;
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if (!hv_clock)
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return 0;
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src = &hv_clock[cpu].pvti;
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low = (int)slow_virt_to_phys(src) | 1;
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high = ((u64)slow_virt_to_phys(src) >> 32);
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ret = native_write_msr_safe(msr_kvm_system_time, low, high);
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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 ret;
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}
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static void kvm_save_sched_clock_state(void)
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{
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}
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static void kvm_restore_sched_clock_state(void)
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{
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kvm_register_clock("primary cpu clock, resume");
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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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}
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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 writing 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_CORE
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static void kvm_crash_shutdown(struct pt_regs *regs)
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{
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native_write_msr(msr_kvm_system_time, 0, 0);
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kvm_disable_steal_time();
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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(msr_kvm_system_time, 0, 0);
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kvm_disable_steal_time();
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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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struct pvclock_vcpu_time_info *vcpu_time;
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unsigned long mem;
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int size, cpu;
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u8 flags;
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size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
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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_CLOCKSOURCE2)) {
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msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
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msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
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} else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
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return;
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printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
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msr_kvm_system_time, msr_kvm_wall_clock);
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mem = memblock_alloc(size, PAGE_SIZE);
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if (!mem)
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return;
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hv_clock = __va(mem);
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memset(hv_clock, 0, size);
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if (kvm_register_clock("primary cpu clock")) {
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hv_clock = NULL;
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memblock_free(mem, size);
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return;
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}
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if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
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pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
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cpu = get_cpu();
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vcpu_time = &hv_clock[cpu].pvti;
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flags = pvclock_read_flags(vcpu_time);
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kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT);
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put_cpu();
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x86_platform.calibrate_tsc = kvm_get_tsc_khz;
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x86_platform.calibrate_cpu = kvm_get_tsc_khz;
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x86_platform.get_wallclock = kvm_get_wallclock;
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x86_platform.set_wallclock = kvm_set_wallclock;
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#ifdef CONFIG_X86_LOCAL_APIC
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x86_cpuinit.early_percpu_clock_init =
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kvm_setup_secondary_clock;
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#endif
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x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
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x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
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machine_ops.shutdown = kvm_shutdown;
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#ifdef CONFIG_KEXEC_CORE
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machine_ops.crash_shutdown = kvm_crash_shutdown;
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#endif
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kvm_get_preset_lpj();
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clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
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pv_info.name = "KVM";
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}
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int __init kvm_setup_vsyscall_timeinfo(void)
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{
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#ifdef CONFIG_X86_64
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int cpu;
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u8 flags;
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struct pvclock_vcpu_time_info *vcpu_time;
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unsigned int size;
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if (!hv_clock)
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return 0;
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size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
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cpu = get_cpu();
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vcpu_time = &hv_clock[cpu].pvti;
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flags = pvclock_read_flags(vcpu_time);
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if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
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put_cpu();
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return 1;
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}
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put_cpu();
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kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
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#endif
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return 0;
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}
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