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locking/pvqspinlock, x86: Enable PV qspinlock for KVM

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This patch adds the necessary KVM specific code to allow KVM to
support the CPU halting and kicking operations needed by the queue
spinlock PV code.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <paolo.bonzini@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-11-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Waiman Long 2015-04-24 14:56:39 -04:00 committed by Ingo Molnar
parent f233f7f158
commit bf0c7c34ad
2 changed files with 44 additions and 1 deletions
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43
arch/x86/kernel/kvm.c
View File

@ -584,6 +584,39 @@ static void kvm_kick_cpu(int cpu)
kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
}
#ifdef CONFIG_QUEUED_SPINLOCK
#include <asm/qspinlock.h>
static void kvm_wait(u8 *ptr, u8 val)
{
unsigned long flags;
if (in_nmi())
return;
local_irq_save(flags);
if (READ_ONCE(*ptr) != val)
goto out;
/*
* halt until it's our turn and kicked. Note that we do safe halt
* for irq enabled case to avoid hang when lock info is overwritten
* in irq spinlock slowpath and no spurious interrupt occur to save us.
*/
if (arch_irqs_disabled_flags(flags))
halt();
else
safe_halt();
out:
local_irq_restore(flags);
}
#else /* !CONFIG_QUEUED_SPINLOCK */
enum kvm_contention_stat {
TAKEN_SLOW,
TAKEN_SLOW_PICKUP,
@ -817,6 +850,8 @@ static void kvm_unlock_kick(struct arch_spinlock *lock, __ticket_t ticket)
}
}
#endif /* !CONFIG_QUEUED_SPINLOCK */
/*
* Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
*/
@ -828,8 +863,16 @@ void __init kvm_spinlock_init(void)
if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
return;
#ifdef CONFIG_QUEUED_SPINLOCK
__pv_init_lock_hash();
pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
pv_lock_ops.wait = kvm_wait;
pv_lock_ops.kick = kvm_kick_cpu;
#else /* !CONFIG_QUEUED_SPINLOCK */
pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
pv_lock_ops.unlock_kick = kvm_unlock_kick;
#endif
}
static __init int kvm_spinlock_init_jump(void)

2
kernel/Kconfig.locks
View File

@ -240,7 +240,7 @@ config ARCH_USE_QUEUED_SPINLOCK
config QUEUED_SPINLOCK
def_bool y if ARCH_USE_QUEUED_SPINLOCK
depends on SMP && !PARAVIRT_SPINLOCKS
depends on SMP && (!PARAVIRT_SPINLOCKS || !XEN)
config ARCH_USE_QUEUE_RWLOCK
bool