1 files changed, 304 insertions, 0 deletions
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
new file mode 100644
index 000000000..42caaef89
--- /dev/null
+++ b/arch/x86/kernel/kvmclock.c
@@ -0,0 +1,304 @@
+/*  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 <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 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();
+}
+
+/*
+ * 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
+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)
+{
+	unsigned long mem;
+	int size;
+
+	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;
+	}
+	pv_time_ops.sched_clock = kvm_clock_read;
+	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
+	machine_ops.crash_shutdown  = kvm_crash_shutdown;
+#endif
+	kvm_get_preset_lpj();
+	clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
+	pv_info.name = "KVM";
+
+	if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
+		pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+}
+
+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;
+}