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From: David Vrabel <david.vrabel@citrix.com>
To: Peter Zijlstra <peterz@infradead.org>, <Waiman.Long@hp.com>
Cc: <raghavendra.kt@linux.vnet.ibm.com>, <kvm@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <hpa@zytor.com>,
	<boris.ostrovsky@oracle.com>, <linux-arch@vger.kernel.org>,
	<x86@kernel.org>, <mingo@redhat.com>, <doug.hatch@hp.com>,
	<xen-devel@lists.xenproject.org>, <paulmck@linux.vnet.ibm.com>,
	<riel@redhat.com>, <scott.norton@hp.com>,
	<paolo.bonzini@gmail.com>, <tglx@linutronix.de>,
	<virtualization@lists.linux-foundation.org>, <oleg@redhat.com>,
	<luto@amacapital.net>, <david.vrabel@citrix.com>,
	<torvalds@linux-foundation.org>
Subject: Re: [Xen-devel] [PATCH 0/9] qspinlock stuff -v15
Date: Thu, 19 Mar 2015 18:01:34 +0000	[thread overview]
Message-ID: <550B0EFE.1040309@citrix.com> (raw)
In-Reply-To: <20150316131613.720617163@infradead.org>

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@citrix.com>
---
 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


  parent reply	other threads:[~2015-03-19 18:01 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-16 13:16 Peter Zijlstra
2015-03-16 13:16 ` [PATCH 1/9] qspinlock: A simple generic 4-byte queue spinlock Peter Zijlstra
2015-03-16 13:16 ` [PATCH 2/9] qspinlock, x86: Enable x86-64 to use " Peter Zijlstra
2015-03-16 13:16 ` [PATCH 3/9] qspinlock: Add pending bit Peter Zijlstra
2015-03-16 13:16 ` [PATCH 4/9] qspinlock: Extract out code snippets for the next patch Peter Zijlstra
2015-03-16 13:16 ` [PATCH 5/9] qspinlock: Optimize for smaller NR_CPUS Peter Zijlstra
2015-03-16 13:16 ` [PATCH 6/9] qspinlock: Use a simple write to grab the lock Peter Zijlstra
2015-03-16 13:16 ` [PATCH 7/9] qspinlock: Revert to test-and-set on hypervisors Peter Zijlstra
2015-03-16 13:16 ` [PATCH 8/9] qspinlock: Generic paravirt support Peter Zijlstra
     [not found]   ` <5509E51D.7040909@hp.com>
2015-03-19 10:12     ` Peter Zijlstra
2015-03-19 12:25       ` Peter Zijlstra
2015-03-19 13:43         ` Peter Zijlstra
2015-03-19 23:25         ` Waiman Long
2015-04-01 16:20         ` Waiman Long
2015-04-01 17:12           ` Peter Zijlstra
2015-04-01 17:42             ` Peter Zijlstra
2015-04-01 18:17               ` Peter Zijlstra
2015-04-01 18:54                 ` Waiman Long
2015-04-01 18:48                   ` Peter Zijlstra
2015-04-01 19:58                     ` Waiman Long
2015-04-01 21:03                       ` Peter Zijlstra
2015-04-02 16:28                         ` Waiman Long
2015-04-02 17:20                           ` Peter Zijlstra
2015-04-02 19:48                             ` Peter Zijlstra
2015-04-03  3:39                               ` Waiman Long
2015-04-03 13:43                               ` Peter Zijlstra
2015-04-01 20:10             ` Waiman Long
2015-03-16 13:16 ` [PATCH 9/9] qspinlock,x86,kvm: Implement KVM support for paravirt qspinlock Peter Zijlstra
     [not found]   ` <550A3863.2060808@hp.com>
2015-03-19 10:01     ` Peter Zijlstra
2015-03-19 21:08       ` Waiman Long
2015-03-20  7:43         ` Raghavendra K T
2015-03-16 14:08 ` [Xen-devel] [PATCH 0/9] qspinlock stuff -v15 David Vrabel
2015-03-18 20:36 ` Waiman Long
2015-03-19 18:01 ` David Vrabel [this message]
2015-03-19 18:32   ` [Xen-devel] " Peter Zijlstra
2015-03-25 19:47 ` Konrad Rzeszutek Wilk
2015-03-26 20:21   ` Peter Zijlstra
2015-03-27 14:07     ` Konrad Rzeszutek Wilk
2015-03-30 16:41       ` Waiman Long
2015-03-30 16:25   ` Waiman Long
2015-03-30 16:29     ` Peter Zijlstra
2015-03-30 16:43       ` Waiman Long
2015-03-27  6:40 ` Raghavendra K T

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