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Re: [Xen-devel] [PATCH RFC v5 8/8] pvqspinlock, x86: Enable KVM to use qspinlock's PV support
- To: Paolo Bonzini <pbonzini@xxxxxxxxxx>
- From: Waiman Long <waiman.long@xxxxxx>
- Date: Thu, 27 Feb 2014 13:36:00 -0500
- Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx, Andi Kleen <andi@xxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Michel Lespinasse <walken@xxxxxxxxxx>, Alok Kataria <akataria@xxxxxxxxxx>, linux-arch@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx, Ingo Molnar <mingo@xxxxxxxxxx>, Scott J Norton <scott.norton@xxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>, Alexander Fyodorov <halcy@xxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, Daniel J Blueman <daniel@xxxxxxxxxxxxx>, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, Oleg Nesterov <oleg@xxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxxxxxx>, George Spelvin <linux@xxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Aswin Chandramouleeswaran <aswin@xxxxxx>, Chegu Vinod <chegu_vinod@xxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, David Vrabel <david.vrabel@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
- Delivery-date: Thu, 27 Feb 2014 18:36:30 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 02/27/2014 04:31 AM, Paolo Bonzini wrote:
static __init int kvm_spinlock_init_jump(void)
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index f185584..a70fdeb 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
+ depends on SMP&& (!PARAVIRT_SPINLOCKS || !XEN)
Should this rather be
def_bool y if ARCH_USE_QUEUE_SPINLOCK&& (!PARAVIRT_SPINLOCKS || !XEN)
?
PARAVIRT_SPINLOCKS + XEN + QUEUE_SPINLOCK + PARAVIRT_UNFAIR_LOCKS is a
valid combination, but it's impossible to choose PARAVIRT_UNFAIR_LOCKS
if QUEUE_SPINLOCK is unavailable.
Paolo
The PV ticketlock code assumes the presence of ticket spinlock. So it
will cause compilation error if QUEUE_SPINLOCK is enabled. My patches
7/8 modified the KVM code so that the PV ticketlock code can coexist
with queue spinlock. As I haven't figure out the proper way to modify
the Xen code, I need to disable the queue spinlock code if
PARAVIRT_SPINLOCKS and XEN are both enabled. However, by disabling
PARAVIRT_SPINLOCKS, we can use PARAVIRT_UNFAIR_LOCKS with XEN.
-Longman
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