From patchwork Thu Sep 29 10:40:04 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Borntraeger X-Patchwork-Id: 9356193 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4FAA46077A for ; Thu, 29 Sep 2016 10:40:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 400DA29938 for ; Thu, 29 Sep 2016 10:40:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 33BE32993C; Thu, 29 Sep 2016 10:40:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6E81229938 for ; Thu, 29 Sep 2016 10:40:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755477AbcI2KkT (ORCPT ); Thu, 29 Sep 2016 06:40:19 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58502 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755342AbcI2KkM (ORCPT ); Thu, 29 Sep 2016 06:40:12 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u8TAcl7h060898 for ; Thu, 29 Sep 2016 06:40:11 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 25rvehb1fg-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 29 Sep 2016 06:40:11 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 29 Sep 2016 11:40:07 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id B65D617D805F; Thu, 29 Sep 2016 11:42:09 +0100 (BST) Received: from d06av09.portsmouth.uk.ibm.com (d06av09.portsmouth.uk.ibm.com [9.149.37.250]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u8TAe7Ei14156100; Thu, 29 Sep 2016 10:40:07 GMT Received: from d06av09.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av09.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u8TAe58A006388; Thu, 29 Sep 2016 04:40:07 -0600 Received: from oc1450873852.ibm.com (dyn-9-152-224-26.boeblingen.de.ibm.com [9.152.224.26]) by d06av09.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u8TAe4m6006365; Thu, 29 Sep 2016 04:40:04 -0600 Subject: Re: [PATCH v3 0/4] implement vcpu preempted check To: Peter Zijlstra , Pan Xinhui References: <1469101514-49475-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> <20160929101040.GV5016@twins.programming.kicks-ass.net> <166f3bad-f700-4624-6c1c-996f90ad609c@de.ibm.com> Cc: 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, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mingo@redhat.com, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, kernellwp@gmail.com, jgross@suse.com, pbonzini@redhat.com, bsingharora@gmail.com, Heiko Carstens From: Christian Borntraeger Date: Thu, 29 Sep 2016 12:40:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <166f3bad-f700-4624-6c1c-996f90ad609c@de.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16092910-0016-0000-0000-00000241DFFD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16092910-0017-0000-0000-00002339BED8 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-09-29_06:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609020000 definitions=main-1609290186 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 09/29/2016 12:23 PM, Christian Borntraeger wrote: > On 09/29/2016 12:10 PM, Peter Zijlstra wrote: >> On Thu, Jul 21, 2016 at 07:45:10AM -0400, Pan Xinhui wrote: >>> change from v2: >>> no code change, fix typos, update some comments >>> >>> change from v1: >>> a simplier definition of default vcpu_is_preempted >>> skip mahcine type check on ppc, and add config. remove dedicated macro. >>> add one patch to drop overload of rwsem_spin_on_owner and mutex_spin_on_owner. >>> add more comments >>> thanks boqun and Peter's suggestion. >>> >>> This patch set aims to fix lock holder preemption issues. >> >> So I really like the concept, but I would also really like to see >> support for more hypervisors included before we can move forward with >> this. >> >> Please consider s390 and (x86/arm) KVM. Once we have a few, more can >> follow later, but I think its important to not only have PPC support for >> this. > > Actually the s390 preemted check via sigp sense running is available for > all hypervisors (z/VM, LPAR and KVM) which implies everywhere as you can no > longer buy s390 systems without LPAR. > > As Heiko already pointed out we could simply use a small inline function > that calls cpu_is_preempted from arch/s390/lib/spinlock (or smp_vcpu_scheduled from smp.c) Maybe something like (untested and just pasted, so white space damaged) If ok I can respin into a proper patch. --- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h index 63ebf37..6e82986 100644 --- a/arch/s390/include/asm/spinlock.h +++ b/arch/s390/include/asm/spinlock.h @@ -21,6 +21,13 @@ _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new) return __sync_bool_compare_and_swap(lock, old, new); } +int arch_vcpu_is_preempted(int cpu); +#define vcpu_is_preempted cpu_is_preempted +static inline bool cpu_is_preempted(int cpu) +{ + return arch_vcpu_is_preempted(cpu); +} + /* * Simple spin lock operations. There are two variants, one clears IRQ's * on the local processor, one does not. diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index e5f50a7..260d179 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -37,7 +37,7 @@ static inline void _raw_compare_and_delay(unsigned int *lock, unsigned int old) asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock)); } -static inline int cpu_is_preempted(int cpu) +int arch_vcpu_is_preempted(int cpu) { if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu)) return 0; @@ -45,6 +45,7 @@ static inline int cpu_is_preempted(int cpu) return 0; return 1; } +EXPORT_SYMBOL(arch_vcpu_is_preempted); void arch_spin_lock_wait(arch_spinlock_t *lp) {