From: Waiman Long <Waiman.Long@hp.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: linux-arch@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
xen-devel@lists.xenproject.org, kvm@vger.kernel.org,
Paolo Bonzini <paolo.bonzini@gmail.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
David Vrabel <david.vrabel@citrix.com>,
Oleg Nesterov <oleg@redhat.com>,
Daniel J Blueman <daniel@numascale.com>,
Scott J Norton <scott.norton@hp.com>,
Douglas Hatch <doug.hatch@hp.com>,
Waiman Long <Waiman.Long@hp.com>
Subject: [PATCH v15 12/15] pvqspinlock, x86: Enable PV qspinlock for Xen
Date: Mon, 6 Apr 2015 22:55:47 -0400 [thread overview]
Message-ID: <1428375350-9213-13-git-send-email-Waiman.Long@hp.com> (raw)
In-Reply-To: <1428375350-9213-1-git-send-email-Waiman.Long@hp.com>
This patch adds the necessary Xen specific code to allow Xen to
support the CPU halting and kicking operations needed by the queue
spinlock PV code.
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
---
arch/x86/xen/spinlock.c | 63 ++++++++++++++++++++++++++++++++++++++++++++---
kernel/Kconfig.locks | 2 +-
2 files changed, 60 insertions(+), 5 deletions(-)
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 956374c..728b45b 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -17,6 +17,55 @@
#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;
+
+#ifdef CONFIG_QUEUE_SPINLOCK
+
+#include <asm/qspinlock.h>
+
+static void xen_qlock_kick(int cpu)
+{
+ xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
+}
+
+/*
+ * Halt the current CPU & release it back to the host
+ */
+static void xen_qlock_wait(u8 *byte, u8 val)
+{
+ int irq = __this_cpu_read(lock_kicker_irq);
+
+ /* If kicker interrupts not initialized yet, just spin */
+ if (irq == -1)
+ return;
+
+ /* clear pending */
+ xen_clear_irq_pending(irq);
+
+ /*
+ * We check the byte value after clearing pending IRQ to make sure
+ * that we won't miss a wakeup event because of the clearing.
+ *
+ * The sync_clear_bit() call in xen_clear_irq_pending() is atomic.
+ * So it is effectively a memory barrier for x86.
+ */
+ if (READ_ONCE(*byte) != val)
+ return;
+
+ /*
+ * 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);
+}
+
+#else /* CONFIG_QUEUE_SPINLOCK */
+
enum xen_contention_stat {
TAKEN_SLOW,
TAKEN_SLOW_PICKUP,
@@ -100,12 +149,9 @@ 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);
@@ -217,6 +263,7 @@ static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next)
}
}
}
+#endif /* CONFIG_QUEUE_SPINLOCK */
static irqreturn_t dummy_handler(int irq, void *dev_id)
{
@@ -280,8 +327,16 @@ void __init xen_init_spinlocks(void)
return;
}
printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
+#ifdef CONFIG_QUEUE_SPINLOCK
+ __pv_init_lock_hash();
+ 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
}
/*
@@ -310,7 +365,7 @@ static __init int xen_parse_nopvspin(char *arg)
}
early_param("xen_nopvspin", xen_parse_nopvspin);
-#ifdef CONFIG_XEN_DEBUG_FS
+#if defined(CONFIG_XEN_DEBUG_FS) && !defined(CONFIG_QUEUE_SPINLOCK)
static struct dentry *d_spin_debug;
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index 537b13e..0b42933 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -240,7 +240,7 @@ 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
config ARCH_USE_QUEUE_RWLOCK
bool
--
1.7.1
next prev parent reply other threads:[~2015-04-07 2:57 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-07 2:55 [PATCH v15 00/15] qspinlock: a 4-byte queue spinlock with PV support Waiman Long
2015-04-07 2:55 ` [PATCH v15 01/15] qspinlock: A simple generic 4-byte queue spinlock Waiman Long
2015-04-07 2:55 ` [PATCH v15 02/15] qspinlock, x86: Enable x86-64 to use " Waiman Long
2015-04-07 2:55 ` [PATCH v15 03/15] qspinlock: Add pending bit Waiman Long
2015-04-07 2:55 ` [PATCH v15 04/15] qspinlock: Extract out code snippets for the next patch Waiman Long
2015-04-07 2:55 ` [PATCH v15 05/15] qspinlock: Optimize for smaller NR_CPUS Waiman Long
2015-04-07 2:55 ` [PATCH v15 06/15] qspinlock: Use a simple write to grab the lock Waiman Long
2015-04-07 2:55 ` [PATCH v15 07/15] qspinlock: Revert to test-and-set on hypervisors Waiman Long
2015-04-07 2:55 ` [PATCH v15 08/15] lfsr: a simple binary Galois linear feedback shift register Waiman Long
2015-04-07 2:55 ` [PATCH v15 09/15] pvqspinlock: Implement simple paravirt support for the qspinlock Waiman Long
2015-04-09 18:13 ` Peter Zijlstra
2015-04-09 18:23 ` Peter Zijlstra
2015-04-09 20:36 ` Waiman Long
2015-04-09 21:41 ` Waiman Long
2015-04-13 14:47 ` Peter Zijlstra
2015-04-13 15:45 ` Waiman Long
2015-04-13 15:08 ` Peter Zijlstra
2015-04-13 15:51 ` Waiman Long
2015-04-13 15:09 ` Peter Zijlstra
2015-04-13 16:19 ` Waiman Long
2015-04-07 2:55 ` [PATCH v15 10/15] pvqspinlock: Implement the paravirt qspinlock for x86 Waiman Long
2015-04-07 2:55 ` [PATCH v15 11/15] pvqspinlock, x86: Enable PV qspinlock for KVM Waiman Long
2015-04-07 2:55 ` Waiman Long [this message]
2015-04-08 12:01 ` [Xen-devel] [PATCH v15 12/15] pvqspinlock, x86: Enable PV qspinlock for Xen David Vrabel
2015-04-08 17:42 ` Waiman Long
2015-04-07 2:55 ` [PATCH v15 13/15] pvqspinlock: Only kick CPU at unlock time Waiman Long
2015-04-09 19:57 ` Peter Zijlstra
2015-04-09 20:07 ` Peter Zijlstra
2015-04-09 22:06 ` Waiman Long
2015-04-07 2:55 ` [PATCH v15 14/15] pvqspinlock: Improve slowpath performance by avoiding cmpxchg Waiman Long
2015-04-07 2:55 ` [PATCH v15 15/15] pvqspinlock: Add debug code to check for PV lock hash sanity Waiman Long
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