From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3t0G7y0Kl9zDvXr for ; Fri, 21 Oct 2016 04:31:41 +1100 (AEDT) Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u9KHSuck122349 for ; Thu, 20 Oct 2016 13:31:39 -0400 Received: from e23smtp09.au.ibm.com (e23smtp09.au.ibm.com [202.81.31.142]) by mx0b-001b2d01.pphosted.com with ESMTP id 266y06vukf-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 20 Oct 2016 13:31:39 -0400 Received: from localhost by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 21 Oct 2016 03:31:36 +1000 Received: from d23relay09.au.ibm.com (d23relay09.au.ibm.com [9.185.63.181]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id EA17A3578053 for ; Fri, 21 Oct 2016 04:31:32 +1100 (EST) Received: from d23av05.au.ibm.com (d23av05.au.ibm.com [9.190.234.119]) by d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u9KHVWnc63963148 for ; Fri, 21 Oct 2016 04:31:32 +1100 Received: from d23av05.au.ibm.com (localhost [127.0.0.1]) by d23av05.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u9KHVVH6004802 for ; Fri, 21 Oct 2016 04:31:32 +1100 From: Pan Xinhui To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, xen-devel-request@lists.xenproject.org, kvm@vger.kernel.org Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mingo@redhat.com, peterz@infradead.org, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, kernellwp@gmail.com, jgross@suse.com, pbonzini@redhat.com, bsingharora@gmail.com, boqun.feng@gmail.com, borntraeger@de.ibm.com, rkrcmar@redhat.com, Pan Xinhui Subject: [PATCH v5 5/9] x86, paravirt: Add interface to support kvm/xen vcpu preempted check Date: Thu, 20 Oct 2016 17:27:50 -0400 In-Reply-To: <1476998874-2089-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> References: <1476998874-2089-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> Message-Id: <1476998874-2089-6-git-send-email-xinhui.pan@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This is to fix some lock holder preemption issues. Some other locks implementation do a spin loop before acquiring the lock itself. Currently kernel has an interface of bool vcpu_is_preempted(int cpu). It takes the cpu as parameter and return true if the cpu is preempted. Then kernel can break the spin loops upon on the retval of vcpu_is_preempted. As kernel has used this interface, So lets support it. To deal with kernel and kvm/xen, add vcpu_is_preempted into struct pv_lock_ops. Then kvm or xen could provide their own implementation to support vcpu_is_preempted. Signed-off-by: Pan Xinhui --- 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 0f400c0..38c3bb7 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 921bea7..0526f59 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 2c55a00..2f204dd 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); -- 2.4.11