From 446f3dc8cc0af59259c6c8b898726fae7ed2c055 Mon Sep 17 00:00:00 2001 From: Pan Xinhui Date: Wed, 2 Nov 2016 05:08:33 -0400 Subject: [PATCH] locking/core, x86/paravirt: Implement vcpu_is_preempted(cpu) for KVM and Xen guests Optimize spinlock and mutex busy-loops by providing a vcpu_is_preempted(cpu) function on KVM and Xen platforms. Extend the pv_lock_ops interface accordingly and implement the callbacks on KVM and Xen. Signed-off-by: Pan Xinhui Signed-off-by: Peter Zijlstra (Intel) [ Translated to English. ] Acked-by: Paolo Bonzini Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds 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: linuxppc-dev@lists.ozlabs.org Cc: mpe@ellerman.id.au Cc: paulmck@linux.vnet.ibm.com Cc: paulus@samba.org Cc: rkrcmar@redhat.com Cc: virtualization@lists.linux-foundation.org Cc: will.deacon@arm.com Cc: xen-devel-request@lists.xenproject.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1478077718-37424-7-git-send-email-xinhui.pan@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/paravirt_types.h | 2 ++ arch/x86/include/asm/spinlock.h | 8 ++++++++ arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ 3 files changed, 16 insertions(+) diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 0f400c0e4979..38c3bb74740f 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -310,6 +310,8 @@ struct pv_lock_ops { void (*wait)(u8 *ptr, u8 val); void (*kick)(int cpu); + + bool (*vcpu_is_preempted)(int cpu); }; /* This contains all the paravirt structures: we get a convenient diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index 921bea7a2708..0526f596e399 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -26,6 +26,14 @@ extern struct static_key paravirt_ticketlocks_enabled; static __always_inline bool static_key_false(struct static_key *key); +#ifdef CONFIG_PARAVIRT_SPINLOCKS +#define vcpu_is_preempted vcpu_is_preempted +static inline bool vcpu_is_preempted(int cpu) +{ + return pv_lock_ops.vcpu_is_preempted(cpu); +} +#endif + #include /* diff --git a/arch/x86/kernel/paravirt-spinlocks.c b/arch/x86/kernel/paravirt-spinlocks.c index 2c55a003b793..2f204dd552a4 100644 --- a/arch/x86/kernel/paravirt-spinlocks.c +++ b/arch/x86/kernel/paravirt-spinlocks.c @@ -21,12 +21,18 @@ bool pv_is_native_spin_unlock(void) __raw_callee_save___native_queued_spin_unlock; } +static bool native_vcpu_is_preempted(int cpu) +{ + return 0; +} + struct pv_lock_ops pv_lock_ops = { #ifdef CONFIG_SMP .queued_spin_lock_slowpath = native_queued_spin_lock_slowpath, .queued_spin_unlock = PV_CALLEE_SAVE(__native_queued_spin_unlock), .wait = paravirt_nop, .kick = paravirt_nop, + .vcpu_is_preempted = native_vcpu_is_preempted, #endif /* SMP */ }; EXPORT_SYMBOL(pv_lock_ops); -- 2.20.1