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>

1 files changed, 180 insertions, 0 deletions

diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c
new file mode 100644
index 000000000000..ec168ec754b2
--- /dev/null
+++ b/arch/ia64/xen/time.c
@@ -0,0 +1,180 @@
+/******************************************************************************
+ * 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,
+};