This patch adds the necessary KVM specific code to allow XEN to support
the sleeping and CPU kicking operations needed by the queue spinlock PV
code.
Signed-off-by: Waiman Long <Waiman.Long@xxxxxx>
---
arch/x86/xen/spinlock.c | 119 +++++++++++++++++++++++++++++++++++++++++++++--
kernel/Kconfig.locks | 2 +-
2 files changed, 115 insertions(+), 6 deletions(-)
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 06f4a64..6bbe798 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -17,6 +17,12 @@
#include "xen-ops.h"
#include "debugfs.h"
+static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
+static DEFINE_PER_CPU(char *, irq_name);
+static bool xen_pvspin = true;
+
+#ifndef CONFIG_QUEUE_SPINLOCK
+
enum xen_contention_stat {
TAKEN_SLOW,
TAKEN_SLOW_PICKUP,
@@ -100,12 +106,9 @@ struct xen_lock_waiting {
__ticket_t want;
};
-static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
-static DEFINE_PER_CPU(char *, irq_name);
static DEFINE_PER_CPU(struct xen_lock_waiting, lock_waiting);
static cpumask_t waiting_cpus;
-static bool xen_pvspin = true;
__visible void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
{
int irq = __this_cpu_read(lock_kicker_irq);
@@ -213,6 +216,94 @@ static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next)
}
}
+#else /* CONFIG_QUEUE_SPINLOCK */
+
+#ifdef CONFIG_XEN_DEBUG_FS
+static u32 kick_stats; /* CPU kick count */
+static u32 kick_nohalt_stats; /* Kick but not halt count */
+static u32 halt_qhead_stats; /* Queue head halting count */
+static u32 halt_qnode_stats; /* Queue node halting count */
+static u32 wake_kick_stats; /* Wakeup by kicking count */
+static u32 wake_spur_stats; /* Spurious wakeup count */
+
+static inline void xen_kick_stats(void)
+{
+ add_smp(&kick_stats, 1);
+}
+
+static inline void xen_halt_stats(enum pv_lock_stats type)
+{
+ if (type == PV_HALT_QHEAD)
+ add_smp(&halt_qhead_stats, 1);
+ else /* type == PV_HALT_QNODE */
+ add_smp(&halt_qnode_stats, 1);
+}
+
+static inline void xen_lock_stats(enum pv_lock_stats type)
+{
+ if (type == PV_WAKE_KICKED)
+ add_smp(&wake_kick_stats, 1);
+ else if (type == PV_WAKE_SPURIOUS)
+ add_smp(&wake_spur_stats, 1);
+ else /* type == PV_KICK_NOHALT */
+ add_smp(&kick_nohalt_stats, 1);
+}
+#else /* CONFIG_XEN_DEBUG_FS */
+static inline void xen_kick_stats(void)
+{
+}
+
+static inline void xen_halt_stats(enum pv_lock_stats type)
+{
+}
+
+static inline void xen_lock_stats(enum pv_lock_stats type)
+{
+}
+#endif /* CONFIG_XEN_DEBUG_FS */
+
+static void xen_kick_cpu(int cpu)
+{
+ xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
+ xen_kick_stats();
+}
+
+/*
+ * Halt the current CPU & release it back to the host
+ */
+static void xen_hibernate(enum pv_lock_stats type)
+{
+ int irq = __this_cpu_read(lock_kicker_irq);
+ unsigned long flags;
+
+ /* If kicker interrupts not initialized yet, just spin */
+ if (irq == -1)
+ return;
+
+ /*
+ * Make sure an interrupt handler can't upset things in a
+ * partially setup state.
+ */
+ local_irq_save(flags);
+
+ xen_halt_stats(type);
+ /* clear pending */
+ xen_clear_irq_pending(irq);
+
+ /* Allow interrupts while blocked */
+ local_irq_restore(flags);
+
+ /*
+ * If an interrupt happens here, it will leave the wakeup irq
+ * pending, which will cause xen_poll_irq() to return
+ * immediately.
+ */
+
+ /* Block until irq becomes pending (or perhaps a spurious wakeup) */
+ xen_poll_irq(irq);
+}
+#endif /* CONFIG_QUEUE_SPINLOCK */
+
static irqreturn_t dummy_handler(int irq, void *dev_id)
{
BUG();
@@ -258,7 +349,6 @@ void xen_uninit_lock_cpu(int cpu)
per_cpu(irq_name, cpu) = NULL;
}
-
/*
* Our init of PV spinlocks is split in two init functions due to us
* using paravirt patching and jump labels patching and having to do
@@ -275,8 +365,14 @@ void __init xen_init_spinlocks(void)
return;
}
+#ifdef CONFIG_QUEUE_SPINLOCK
+ pv_lock_ops.kick_cpu = xen_kick_cpu;
+ pv_lock_ops.hibernate = xen_hibernate;
+ pv_lock_ops.lockstat = xen_lock_stats;
+#else
pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(xen_lock_spinning);
pv_lock_ops.unlock_kick = xen_unlock_kick;
+#endif
}
/*
@@ -318,6 +414,7 @@ static int __init xen_spinlock_debugfs(void)
d_spin_debug = debugfs_create_dir("spinlocks", d_xen);
+#ifndef CONFIG_QUEUE_SPINLOCK
debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);
debugfs_create_u32("taken_slow", 0444, d_spin_debug,
@@ -337,7 +434,19 @@ static int __init xen_spinlock_debugfs(void)
debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);
-
+#else /* CONFIG_QUEUE_SPINLOCK */
+ debugfs_create_u32("kick_stats", 0644, d_spin_debug, &kick_stats);
+ debugfs_create_u32("kick_nohalt_stats",
+ 0644, d_spin_debug, &kick_nohalt_stats);
+ debugfs_create_u32("halt_qhead_stats",
+ 0644, d_spin_debug, &halt_qhead_stats);
+ debugfs_create_u32("halt_qnode_stats",
+ 0644, d_spin_debug, &halt_qnode_stats);
+ debugfs_create_u32("wake_kick_stats",
+ 0644, d_spin_debug, &wake_kick_stats);
+ debugfs_create_u32("wake_spur_stats",
+ 0644, d_spin_debug, &wake_spur_stats);
+#endif /* CONFIG_QUEUE_SPINLOCK */
return 0;
}
fs_initcall(xen_spinlock_debugfs);
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index a70fdeb..451e392 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -229,4 +229,4 @@ config ARCH_USE_QUEUE_SPINLOCK
config QUEUE_SPINLOCK
def_bool y if ARCH_USE_QUEUE_SPINLOCK
- depends on SMP && (!PARAVIRT_SPINLOCKS || !XEN)
+ depends on SMP
--
1.7.1
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