ia64/pv_ops/xen: implement xen pv_time_ops.

implement xen pv_time_ops to account steal time.

Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/xen/Makefile

@@ -3,7 +3,7 @@
 #
 
 obj-y := hypercall.o xenivt.o xensetup.o xen_pv_ops.o irq_xen.o \
-	 hypervisor.o xencomm.o xcom_hcall.o grant-table.o
+	 hypervisor.o xencomm.o xcom_hcall.o grant-table.o time.o
 
 AFLAGS_xenivt.o += -D__IA64_ASM_PARAVIRTUALIZED_XEN
 

arch/ia64/xen/time.c

+/******************************************************************************
+ * arch/ia64/xen/time.c
+ *
+ * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
+ *                    VA Linux Systems Japan K.K.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/kernel_stat.h>
+#include <linux/posix-timers.h>
+#include <linux/irq.h>
+#include <linux/clocksource.h>
+
+#include <asm/xen/hypervisor.h>
+
+#include <xen/interface/vcpu.h>
+
+#include "../kernel/fsyscall_gtod_data.h"
+
+DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
+DEFINE_PER_CPU(unsigned long, processed_stolen_time);
+DEFINE_PER_CPU(unsigned long, processed_blocked_time);
+
+/* taken from i386/kernel/time-xen.c */
+static void xen_init_missing_ticks_accounting(int cpu)
+{
+	struct vcpu_register_runstate_memory_area area;
+	struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
+	int rc;
+
+	memset(runstate, 0, sizeof(*runstate));
+
+	area.addr.v = runstate;
+	rc = HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu,
+				&area);
+	WARN_ON(rc && rc != -ENOSYS);
+
+	per_cpu(processed_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
+	per_cpu(processed_stolen_time, cpu) = runstate->time[RUNSTATE_runnable]
+					    + runstate->time[RUNSTATE_offline];
+}
+
+/*
+ * Runstate accounting
+ */
+/* stolen from arch/x86/xen/time.c */
+static void get_runstate_snapshot(struct vcpu_runstate_info *res)
+{
+	u64 state_time;
+	struct vcpu_runstate_info *state;
+
+	BUG_ON(preemptible());
+
+	state = &__get_cpu_var(runstate);
+
+	/*
+	 * The runstate info is always updated by the hypervisor on
+	 * the current CPU, so there's no need to use anything
+	 * stronger than a compiler barrier when fetching it.
+	 */
+	do {
+		state_time = state->state_entry_time;
+		rmb();
+		*res = *state;
+		rmb();
+	} while (state->state_entry_time != state_time);
+}
+
+#define NS_PER_TICK (1000000000LL/HZ)
+
+static unsigned long
+consider_steal_time(unsigned long new_itm)
+{
+	unsigned long stolen, blocked;
+	unsigned long delta_itm = 0, stolentick = 0;
+	int cpu = smp_processor_id();
+	struct vcpu_runstate_info runstate;
+	struct task_struct *p = current;
+
+	get_runstate_snapshot(&runstate);
+
+	/*
+	 * Check for vcpu migration effect
+	 * In this case, itc value is reversed.
+	 * This causes huge stolen value.
+	 * This function just checks and reject this effect.
+	 */
+	if (!time_after_eq(runstate.time[RUNSTATE_blocked],
+			   per_cpu(processed_blocked_time, cpu)))
+		blocked = 0;
+
+	if (!time_after_eq(runstate.time[RUNSTATE_runnable] +
+			   runstate.time[RUNSTATE_offline],
+			   per_cpu(processed_stolen_time, cpu)))
+		stolen = 0;
+
+	if (!time_after(delta_itm + new_itm, ia64_get_itc()))
+		stolentick = ia64_get_itc() - new_itm;
+
+	do_div(stolentick, NS_PER_TICK);
+	stolentick++;
+
+	do_div(stolen, NS_PER_TICK);
+
+	if (stolen > stolentick)
+		stolen = stolentick;
+
+	stolentick -= stolen;
+	do_div(blocked, NS_PER_TICK);
+
+	if (blocked > stolentick)
+		blocked = stolentick;
+
+	if (stolen > 0 || blocked > 0) {
+		account_steal_time(NULL, jiffies_to_cputime(stolen));
+		account_steal_time(idle_task(cpu), jiffies_to_cputime(blocked));
+		run_local_timers();
+
+		if (rcu_pending(cpu))
+			rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
+
+		scheduler_tick();
+		run_posix_cpu_timers(p);
+		delta_itm += local_cpu_data->itm_delta * (stolen + blocked);
+
+		if (cpu == time_keeper_id) {
+			write_seqlock(&xtime_lock);
+			do_timer(stolen + blocked);
+			local_cpu_data->itm_next = delta_itm + new_itm;
+			write_sequnlock(&xtime_lock);
+		} else {
+			local_cpu_data->itm_next = delta_itm + new_itm;
+		}
+		per_cpu(processed_stolen_time, cpu) += NS_PER_TICK * stolen;
+		per_cpu(processed_blocked_time, cpu) += NS_PER_TICK * blocked;
+	}
+	return delta_itm;
+}
+
+static int xen_do_steal_accounting(unsigned long *new_itm)
+{
+	unsigned long delta_itm;
+	delta_itm = consider_steal_time(*new_itm);
+	*new_itm += delta_itm;
+	if (time_after(*new_itm, ia64_get_itc()) && delta_itm)
+		return 1;
+
+	return 0;
+}
+
+static void xen_itc_jitter_data_reset(void)
+{
+	u64 lcycle, ret;
+
+	do {
+		lcycle = itc_jitter_data.itc_lastcycle;
+		ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, 0);
+	} while (unlikely(ret != lcycle));
+}
+
+struct pv_time_ops xen_time_ops __initdata = {
+	.init_missing_ticks_accounting	= xen_init_missing_ticks_accounting,
+	.do_steal_accounting		= xen_do_steal_accounting,
+	.clocksource_resume		= xen_itc_jitter_data_reset,
+};

arch/ia64/xen/time.h

+/******************************************************************************
+ * arch/ia64/xen/time.h
+ *
+ * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
+ *                    VA Linux Systems Japan K.K.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+extern struct pv_time_ops xen_time_ops __initdata;

arch/ia64/xen/xen_pv_ops.c

@@ -30,6 +30,7 @@
 #include <asm/xen/privop.h>
 
 #include "irq_xen.h"
+#include "time.h"
 
 /***************************************************************************
  * general info
@@ -357,6 +358,7 @@ xen_setup_pv_ops(void)
 	pv_cpu_ops = xen_cpu_ops;
 	pv_iosapic_ops = xen_iosapic_ops;
 	pv_irq_ops = xen_irq_ops;
+	pv_time_ops = xen_time_ops;
 
 	paravirt_cpu_asm_init(&xen_cpu_asm_switch);
 }