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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 4B791C433DB for ; Wed, 10 Mar 2021 07:53:06 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A7D9F64FE5 for ; Wed, 10 Mar 2021 07:53:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7D9F64FE5 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Type: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:Date:Message-ID:Subject:From:References:Cc:To: Reply-To:Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date :Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qt37I7x+wRTRq3ZTz00RT+pYo/nrhiV3TGDpGai81pw=; b=n0ofVoLDAlDacahN0Q+I1z8rK sHE5xlgG/jJhldkELX1ImIV1DxE8t1Vepi2qTDBTZ5SBAeNzNEwng3j5P4m+QnstBV+zbyMG32+C1 CYTObo5DRXHWQY64acSgHQ1MJxbRvJ+2sIHPDSJo32OAeDzKVT4RGJKn0CX5fFQiArm30t//FcwB4 /uS5c2oJINrU35R3+uRuo5ydYZ8TIDkUNBO/wuK6A5PyVD9+gmukK4YujvMGHPM3ZkwBoGL8wrVMu ll127+zF16BwHw9IjoxiIOuj492Tooz+TXJGERFbWANH+zvMz6LzIq9abTAXVl15ShvJPXSD8UJkN VBPQzg8EA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lJtcy-006GOL-0W; Wed, 10 Mar 2021 07:51:33 +0000 Received: from mx2.suse.de ([195.135.220.15]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lJtcr-006GNI-7l for linux-arm-kernel@lists.infradead.org; Wed, 10 Mar 2021 07:51:27 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1615362684; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OdJhwschBXvB5hNHxMQE7ci5qnJUnPFBXFeYxWWs7LU=; b=MIhzv4U/6I9MUcLzMLr7qFZ5XDlYOMx+4qXKrm3bpB5MI6rXn4/VWVUmQNesLyQK4JWPsZ NyTSsAP5d6dlFcaGiMseRqojsKxIlKlVF2qv7qQl7w/FdImJGPHAb7HgqO6EnT98wcyJpB SPmxzqannDTIg0oRcNf4OS81xpo3XRQ= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 79E63AC1F; Wed, 10 Mar 2021 07:51:24 +0000 (UTC) To: Borislav Petkov Cc: xen-devel@lists.xenproject.org, x86@kernel.org, virtualization@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, Deep Shah , "VMware, Inc." , Russell King , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Boris Ostrovsky , Stefano Stabellini , Peter Zijlstra References: <20210309134813.23912-1-jgross@suse.com> <20210309134813.23912-3-jgross@suse.com> <20210309185737.GE699@zn.tnic> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Subject: Re: [PATCH v6 02/12] x86/paravirt: switch time pvops functions to use static_call() Message-ID: Date: Wed, 10 Mar 2021 08:51:22 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210309185737.GE699@zn.tnic> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210310_075125_670436_83F0FD1A X-CRM114-Status: GOOD ( 20.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============1005859086901549526==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --===============1005859086901549526== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nna0TkS6ABUg1IonAzP3y7arxA0rrchGS" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --nna0TkS6ABUg1IonAzP3y7arxA0rrchGS Content-Type: multipart/mixed; boundary="q9XNVycbGdPhE1GVCGpTpAYFf6uHIwdvx"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: Borislav Petkov Cc: xen-devel@lists.xenproject.org, x86@kernel.org, virtualization@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, Deep Shah , "VMware, Inc." , Russell King , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Boris Ostrovsky , Stefano Stabellini , Peter Zijlstra Message-ID: Subject: Re: [PATCH v6 02/12] x86/paravirt: switch time pvops functions to use static_call() References: <20210309134813.23912-1-jgross@suse.com> <20210309134813.23912-3-jgross@suse.com> <20210309185737.GE699@zn.tnic> In-Reply-To: <20210309185737.GE699@zn.tnic> --q9XNVycbGdPhE1GVCGpTpAYFf6uHIwdvx Content-Type: multipart/mixed; boundary="------------B707D43FD7210F09477B06A5" Content-Language: en-US This is a multi-part message in MIME format. --------------B707D43FD7210F09477B06A5 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 09.03.21 19:57, Borislav Petkov wrote: > On Tue, Mar 09, 2021 at 02:48:03PM +0100, Juergen Gross wrote: >> @@ -167,6 +168,17 @@ static u64 native_steal_clock(int cpu) >> return 0; >> } >> =20 >> +DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock); >> +DEFINE_STATIC_CALL(pv_sched_clock, native_sched_clock); >> + >> +bool paravirt_using_native_sched_clock =3D true; >> + >> +void paravirt_set_sched_clock(u64 (*func)(void)) >> +{ >> + static_call_update(pv_sched_clock, func); >> + paravirt_using_native_sched_clock =3D (func =3D=3D native_sched_cloc= k); >> +} >=20 > What's the point of this function if there's a global > paravirt_using_native_sched_clock variable now? It is combining the two needed actions: update the static call and set the paravirt_using_native_sched_clock boolean. > Looking how the bit of information whether native_sched_clock is used, > is needed in tsc.c, it probably would be cleaner if you add a >=20 > set_sched_clock_native(void); >=20 > or so, to tsc.c instead and call that here and make that long var name = a > a shorter and static one in tsc.c instead. I need to transfer a boolean value, so it would need to be set_sched_clock_native(bool state); In the end the difference is only marginal IMO. Just had another idea: I could add a function to static_call.h for querying the current function. This would avoid the double book keeping and could probably be used later when switching other pv_ops calls to static_call, too (e.g. pv_is_native_spin_unlock()). What do you think? 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