On 16/03/15 13:16, Peter Zijlstra wrote:
>
> I feel that if someone were to do a Xen patch we can go ahead and merge this
> stuff (finally!).
This seems work for me, but I've not got time to give it a more thorough
testing.
You can fold this into your series.
There doesn't seem to be a way to disable QUEUE_SPINLOCKS when supported by
the arch, is this intentional? If so, the existing ticketlock code could go.
David
8<------------------------------
x86/xen: paravirt support for qspinlocks
Provide the wait and kick ops necessary for paravirt-aware queue
spinlocks.
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
arch/x86/xen/spinlock.c | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 956374c..b019b2a 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -95,17 +95,43 @@ static inline void spin_time_accum_blocked(u64 start)
}
#endif /* CONFIG_XEN_DEBUG_FS */
+static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
+static DEFINE_PER_CPU(char *, irq_name);
+static bool xen_pvspin = true;
+
+#ifdef CONFIG_QUEUE_SPINLOCK
+
+#include <asm/qspinlock.h>
+
+PV_CALLEE_SAVE_REGS_THUNK(__pv_queue_spin_unlock);
+
+static void xen_qlock_wait(u8 *ptr, u8 val)
+{
+ int irq = __this_cpu_read(lock_kicker_irq);
+
+ xen_clear_irq_pending(irq);
+
+ barrier();
+
+ if (READ_ONCE(*ptr) == val)
+ xen_poll_irq(irq);
+}
+
+static void xen_qlock_kick(int cpu)
+{
+ xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
+}
+
+#else
+
struct xen_lock_waiting {
struct arch_spinlock *lock;
__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);
@@ -217,6 +243,7 @@ static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next)
}
}
}
+#endif /* !QUEUE_SPINLOCK */
static irqreturn_t dummy_handler(int irq, void *dev_id)
{
@@ -280,8 +307,15 @@ void __init xen_init_spinlocks(void)
return;
}
printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
+#ifdef CONFIG_QUEUE_SPINLOCK
+ pv_lock_ops.queue_spin_lock_slowpath = __pv_queue_spin_lock_slowpath;
+ pv_lock_ops.queue_spin_unlock = PV_CALLEE_SAVE(__pv_queue_spin_unlock);
+ pv_lock_ops.wait = xen_qlock_wait;
+ pv_lock_ops.kick = xen_qlock_kick;
+#else
pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(xen_lock_spinning);
pv_lock_ops.unlock_kick = xen_unlock_kick;
+#endif
}
/*
--
1.7.10.4
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