From 3cded41794818d788aa1dc028ede4a1c1222d937 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 15 Nov 2016 16:47:06 +0100 Subject: x86/paravirt: Optimize native pv_lock_ops.vcpu_is_preempted() Avoid the pointless function call to pv_lock_ops.vcpu_is_preempted() when a paravirt spinlock enabled kernel is ran on native hardware. Do this by patching out the CALL instruction with "XOR %RAX,%RAX" which has the same effect (0 return value). Signed-off-by: Peter Zijlstra (Intel) Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Pan Xinhui Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: benh@kernel.crashing.org Cc: boqun.feng@gmail.com Cc: borntraeger@de.ibm.com Cc: bsingharora@gmail.com Cc: dave@stgolabs.net Cc: jgross@suse.com Cc: kernellwp@gmail.com Cc: konrad.wilk@oracle.com Cc: mpe@ellerman.id.au Cc: paulmck@linux.vnet.ibm.com Cc: paulus@samba.org Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Cc: will.deacon@arm.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/qspinlock.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/x86/include/asm/qspinlock.h') diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h index eaba08076030..c343ab52579f 100644 --- a/arch/x86/include/asm/qspinlock.h +++ b/arch/x86/include/asm/qspinlock.h @@ -32,6 +32,12 @@ static inline void queued_spin_unlock(struct qspinlock *lock) { pv_queued_spin_unlock(lock); } + +#define vcpu_is_preempted vcpu_is_preempted +static inline bool vcpu_is_preempted(int cpu) +{ + return pv_vcpu_is_preempted(cpu); +} #else static inline void queued_spin_unlock(struct qspinlock *lock) { -- cgit v1.2.3