From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF596ECDFAA for ; Wed, 18 Jul 2018 08:19:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7580920693 for ; Wed, 18 Jul 2018 08:19:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="UqiHFvEg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7580920693 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730252AbeGRI4I (ORCPT ); Wed, 18 Jul 2018 04:56:08 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:57620 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726110AbeGRI4H (ORCPT ); Wed, 18 Jul 2018 04:56:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=oWybjPG8JArHBKVsTpY+gkdehyEb0Pp9XhIyVkt73R8=; b=UqiHFvEgrUnLY1iuL4O/Mn1Vy QtQoaf567Ljor1EQWRzHytgf/M6KvpUuMC5UVES+XQlYSAQff4pnV0Y5WDCJpl928h+x6BWCtbGw0 A3JK+yTHJ9iDIU6cwidZH0/qTtLgCzOfQoKvEXHhzZvIKDZh90I99Lu+IMhUKf1b12NbgxU4PcM/f 7xbcQSJZgplZ/L/ZCKqzQDZARsBP1dh03JVDNTi6/LFYTWO3h3X/8YmXtShS3wi9++/7P+3Uz1mWl i0zLHXgaNKYYoDM1H581udk/gy1xaxGtCaeY7D3QoTwtQvbKKn3C5T0MprD5bPo3W+eIKZjDYJDXM Z/mnzbyEA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1ffhg9-0000rx-0X; Wed, 18 Jul 2018 08:19:21 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6873420289330; Wed, 18 Jul 2018 10:19:18 +0200 (CEST) Date: Wed, 18 Jul 2018 10:19:18 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, Will Deacon , Joe Mario Subject: Re: [PATCH] x86/pvqspinlock: Use LOCK_PREFIX in __pv_queued_spin_unlock assembly code Message-ID: <20180718081918.GO2494@hirez.programming.kicks-ass.net> References: <1531858560-21547-1-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1531858560-21547-1-git-send-email-longman@redhat.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 17, 2018 at 04:16:00PM -0400, Waiman Long wrote: > The LOCK_PREFIX macro should be used in the assembly > __raw_callee_save___pv_queued_spin_unlock code so that the lock prefix > can be patched out on UP systems. True; but does paravirt locking realy make sense on UP guests? > Signed-off-by: Waiman Long > --- > arch/x86/include/asm/qspinlock_paravirt.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h > index 9ef5ee0..159622e 100644 > --- a/arch/x86/include/asm/qspinlock_paravirt.h > +++ b/arch/x86/include/asm/qspinlock_paravirt.h > @@ -43,7 +43,7 @@ > "push %rdx;" > "mov $0x1,%eax;" > "xor %edx,%edx;" > - "lock cmpxchg %dl,(%rdi);" > + LOCK_PREFIX "cmpxchg %dl,(%rdi);" > "cmp $0x1,%al;" > "jne .slowpath;" > "pop %rdx;" > -- > 1.8.3.1 >