From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751163AbcGFE6l (ORCPT ); Wed, 6 Jul 2016 00:58:41 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41031 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750864AbcGFE6k (ORCPT ); Wed, 6 Jul 2016 00:58:40 -0400 X-IBM-Helo: d23dlp03.au.ibm.com X-IBM-MailFrom: xinhui.pan@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org;linux-s390@vger.kernel.org Date: Wed, 06 Jul 2016 12:58:11 +0800 From: xinhui User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Wanpeng Li CC: "linux-kernel@vger.kernel.org" , linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-s390 , Peter Zijlstra , Ingo Molnar , mpe@ellerman.id.au, Paul Mackerras , benh@kernel.crashing.org, Paul McKenney , Waiman Long , will.deacon@arm.com, boqun.feng@gmail.com, Davidlohr Bueso , schwidefsky@de.ibm.com Subject: Re: [PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check References: <1467124991-13164-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> <1467124991-13164-3-git-send-email-xinhui.pan@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16070604-0008-0000-0000-000000A182CE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16070604-0009-0000-0000-0000079973CB Message-Id: <577C8FE3.3010208@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-06_03:,, 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=8.0.1-1604210000 definitions=main-1607060044 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, wanpeng On 2016年07月05日 17:57, Wanpeng Li wrote: > Hi Xinhui, > 2016-06-28 22:43 GMT+08:00 Pan Xinhui : >> 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 take 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. >> >> Only pSeries need supoort it. And the fact is powerNV are built into same >> kernel image with pSeries. So we need return false if we are runnig as >> powerNV. The another fact is that lppaca->yiled_count keeps zero on >> powerNV. So we can just skip the machine type. > > Lock holder vCPU preemption can be detected by hardware pSeries or > paravirt method? > There is one shard struct between kernel and powerVM/KVM. And we read the yield_count of this struct to detect if one vcpu is running or not. SO it's easy for ppc to implement such interface. Note that yield_count is set by powerVM/KVM. and only pSeries can run a guest for now. :) I also review x86 related code, looks like we need add one hyer-call to get such vcpu preemption info? thanks xinui > Regards, > Wanpeng Li > From mboxrd@z Thu Jan 1 00:00:00 1970 From: xinhui Subject: Re: [PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check Date: Wed, 06 Jul 2016 12:58:11 +0800 Message-ID: <577C8FE3.3010208@linux.vnet.ibm.com> References: <1467124991-13164-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> <1467124991-13164-3-git-send-email-xinhui.pan@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Wanpeng Li Cc: linux-s390 , Davidlohr Bueso , Peter Zijlstra , mpe@ellerman.id.au, boqun.feng@gmail.com, will.deacon@arm.com, "linux-kernel@vger.kernel.org" , Waiman Long , virtualization@lists.linux-foundation.org, Ingo Molnar , Paul Mackerras , benh@kernel.crashing.org, schwidefsky@de.ibm.com, Paul McKenney , linuxppc-dev@lists.ozlabs.org List-Id: virtualization@lists.linuxfoundation.org SGksIHdhbnBlbmcKCk9uIDIwMTblubQwN+aciDA15pelIDE3OjU3LCBXYW5wZW5nIExpIHdyb3Rl Ogo+IEhpIFhpbmh1aSwKPiAyMDE2LTA2LTI4IDIyOjQzIEdNVCswODowMCBQYW4gWGluaHVpIDx4 aW5odWkucGFuQGxpbnV4LnZuZXQuaWJtLmNvbT46Cj4+IFRoaXMgaXMgdG8gZml4IHNvbWUgbG9j ayBob2xkZXIgcHJlZW1wdGlvbiBpc3N1ZXMuIFNvbWUgb3RoZXIgbG9ja3MKPj4gaW1wbGVtZW50 YXRpb24gZG8gYSBzcGluIGxvb3AgYmVmb3JlIGFjcXVpcmluZyB0aGUgbG9jayBpdHNlbGYuIEN1 cnJlbnRseQo+PiBrZXJuZWwgaGFzIGFuIGludGVyZmFjZSBvZiBib29sIHZjcHVfaXNfcHJlZW1w dGVkKGludCBjcHUpLiBJdCB0YWtlIHRoZSBjcHUKPj4gYXMgcGFyYW1ldGVyIGFuZCByZXR1cm4g dHJ1ZSBpZiB0aGUgY3B1IGlzIHByZWVtcHRlZC4gVGhlbiBrZXJuZWwgY2FuIGJyZWFrCj4+IHRo ZSBzcGluIGxvb3BzIHVwb24gb24gdGhlIHJldHZhbCBvZiB2Y3B1X2lzX3ByZWVtcHRlZC4KPj4K Pj4gQXMga2VybmVsIGhhcyB1c2VkIHRoaXMgaW50ZXJmYWNlLCBTbyBsZXRzIHN1cHBvcnQgaXQu Cj4+Cj4+IE9ubHkgcFNlcmllcyBuZWVkIHN1cG9vcnQgaXQuIEFuZCB0aGUgZmFjdCBpcyBwb3dl ck5WIGFyZSBidWlsdCBpbnRvIHNhbWUKPj4ga2VybmVsIGltYWdlIHdpdGggcFNlcmllcy4gU28g d2UgbmVlZCByZXR1cm4gZmFsc2UgaWYgd2UgYXJlIHJ1bm5pZyBhcwo+PiBwb3dlck5WLiBUaGUg YW5vdGhlciBmYWN0IGlzIHRoYXQgbHBwYWNhLT55aWxlZF9jb3VudCBrZWVwcyB6ZXJvIG9uCj4+ IHBvd2VyTlYuIFNvIHdlIGNhbiBqdXN0IHNraXAgdGhlIG1hY2hpbmUgdHlwZS4KPgo+IExvY2sg aG9sZGVyIHZDUFUgcHJlZW1wdGlvbiBjYW4gYmUgZGV0ZWN0ZWQgYnkgaGFyZHdhcmUgcFNlcmll cyBvcgo+IHBhcmF2aXJ0IG1ldGhvZD8KPgpUaGVyZSBpcyBvbmUgc2hhcmQgc3RydWN0IGJldHdl ZW4ga2VybmVsIGFuZCBwb3dlclZNL0tWTS4gQW5kIHdlIHJlYWQgdGhlIHlpZWxkX2NvdW50IG9m IHRoaXMgc3RydWN0IHRvIGRldGVjdCBpZiBvbmUgdmNwdSBpcyBydW5uaW5nIG9yIG5vdC4KU08g aXQncyBlYXN5IGZvciBwcGMgdG8gaW1wbGVtZW50IHN1Y2ggaW50ZXJmYWNlLiBOb3RlIHRoYXQg eWllbGRfY291bnQgaXMgc2V0IGJ5IHBvd2VyVk0vS1ZNLgphbmQgb25seSBwU2VyaWVzIGNhbiBy dW4gYSBndWVzdCBmb3Igbm93LiA6KQoKSSBhbHNvIHJldmlldyB4ODYgcmVsYXRlZCBjb2RlLCBs b29rcyBsaWtlIHdlIG5lZWQgYWRkIG9uZSBoeWVyLWNhbGwgdG8gZ2V0IHN1Y2ggdmNwdSBwcmVl bXB0aW9uIGluZm8/Cgp0aGFua3MKeGludWkKPiBSZWdhcmRzLAo+IFdhbnBlbmcgTGkKPgoKX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KVmlydHVhbGl6YXRp b24gbWFpbGluZyBsaXN0ClZpcnR1YWxpemF0aW9uQGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3Jn Cmh0dHBzOi8vbGlzdHMubGludXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL3ZpcnR1 YWxpemF0aW9u