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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 AB299C433EF for ; Mon, 9 Sep 2019 07:24:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 789B5222C4 for ; Mon, 9 Sep 2019 07:24:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388044AbfIIHYI (ORCPT ); Mon, 9 Sep 2019 03:24:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43180 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727736AbfIIHYI (ORCPT ); Mon, 9 Sep 2019 03:24:08 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E367E18C428C; Mon, 9 Sep 2019 07:24:07 +0000 (UTC) Received: from [10.72.12.61] (ovpn-12-61.pek2.redhat.com [10.72.12.61]) by smtp.corp.redhat.com (Postfix) with ESMTP id 970AF1001948; Mon, 9 Sep 2019 07:24:00 +0000 (UTC) Subject: Re: [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jgg@mellanox.com, aarcange@redhat.com, jglisse@redhat.com, linux-mm@kvack.org, James Bottomley , Christoph Hellwig , David Miller , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org References: <20190905122736.19768-1-jasowang@redhat.com> <20190905122736.19768-3-jasowang@redhat.com> <20190908063618-mutt-send-email-mst@kernel.org> <1cb5aa8d-6213-5fce-5a77-fcada572c882@redhat.com> <20190909004504-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <4ee20058-0beb-111c-6750-556965423f04@redhat.com> Date: Mon, 9 Sep 2019 15:23:58 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190909004504-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.62]); Mon, 09 Sep 2019 07:24:08 +0000 (UTC) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On 2019/9/9 下午12:45, Michael S. Tsirkin wrote: >>> Since idx can be speculated, I guess we need array_index_nospec here? >> So we have >> >> ACQUIRE(mmu_lock) >> >> get idx >> >> RELEASE(mmu_lock) >> >> ACQUIRE(mmu_lock) >> >> read array[idx] >> >> RELEASE(mmu_lock) >> >> Then I think idx can't be speculated consider we've passed RELEASE + >> ACQUIRE? > I don't think memory barriers have anything to do with speculation, > they are architectural. > Oh right. Let me add array_index_nospec() in next version. Thanks 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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 A1BCFC433EF for ; Mon, 9 Sep 2019 07:24:24 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 76036222C5 for ; Mon, 9 Sep 2019 07:24:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="NoiDvXlp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76036222C5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=c/O0XgI3Fnf5NZQCWdIbvd0SzfDqiqLnIcDM4cwWmWg=; b=NoiDvXlpjJNsRecG6Bg3LXMQ+ O+VB9Qlld/cPnBmmVN7g3PhsJs9Y57+4IUFt2ydx6KQ28wKK/raNfKlReEutI8knRXT1Qt+DLhIXz 0XgZfNqdtDe9Rad9xX4kDijQgnHi7rSwBNS1kizAq7JDDxsIv9Dc5DE44hgzpVdbGQHiY9nzndYgm NVTA8hG1QcFqATqRjSnu7b9tJQ+zt/PdnOQylqr061qNakfhMNvcSwaSgdl8xdSdWjWIrtbUNKlh6 TI3XpT3SEeKEMglTfsSuo4dp8+QSjcsqQxcGPN0/Yt6xyDTfo3QJbKfu93rgHlMtvgB3AXaGvoAUu Qpvk/EzHw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i7E20-0002xM-OZ; Mon, 09 Sep 2019 07:24:12 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i7E1w-0002wZ-Uy for linux-arm-kernel@lists.infradead.org; Mon, 09 Sep 2019 07:24:10 +0000 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E367E18C428C; Mon, 9 Sep 2019 07:24:07 +0000 (UTC) Received: from [10.72.12.61] (ovpn-12-61.pek2.redhat.com [10.72.12.61]) by smtp.corp.redhat.com (Postfix) with ESMTP id 970AF1001948; Mon, 9 Sep 2019 07:24:00 +0000 (UTC) Subject: Re: [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address To: "Michael S. Tsirkin" References: <20190905122736.19768-1-jasowang@redhat.com> <20190905122736.19768-3-jasowang@redhat.com> <20190908063618-mutt-send-email-mst@kernel.org> <1cb5aa8d-6213-5fce-5a77-fcada572c882@redhat.com> <20190909004504-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <4ee20058-0beb-111c-6750-556965423f04@redhat.com> Date: Mon, 9 Sep 2019 15:23:58 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190909004504-mutt-send-email-mst@kernel.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.62]); Mon, 09 Sep 2019 07:24:08 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190909_002409_017098_72609C49 X-CRM114-Status: GOOD ( 12.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aarcange@redhat.com, Christoph Hellwig , linux-parisc@vger.kernel.org, kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, James Bottomley , linux-mm@kvack.org, jglisse@redhat.com, jgg@mellanox.com, David Miller , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Ck9uIDIwMTkvOS85IOS4i+WNiDEyOjQ1LCBNaWNoYWVsIFMuIFRzaXJraW4gd3JvdGU6Cj4+PiBT aW5jZSBpZHggY2FuIGJlIHNwZWN1bGF0ZWQsIEkgZ3Vlc3Mgd2UgbmVlZCBhcnJheV9pbmRleF9u b3NwZWMgaGVyZT8KPj4gU28gd2UgaGF2ZQo+Pgo+PiBBQ1FVSVJFKG1tdV9sb2NrKQo+Pgo+PiBn ZXQgaWR4Cj4+Cj4+IFJFTEVBU0UobW11X2xvY2spCj4+Cj4+IEFDUVVJUkUobW11X2xvY2spCj4+ Cj4+IHJlYWQgYXJyYXlbaWR4XQo+Pgo+PiBSRUxFQVNFKG1tdV9sb2NrKQo+Pgo+PiBUaGVuIEkg dGhpbmsgaWR4IGNhbid0IGJlIHNwZWN1bGF0ZWQgY29uc2lkZXIgd2UndmUgcGFzc2VkIFJFTEVB U0UgKwo+PiBBQ1FVSVJFPwo+IEkgZG9uJ3QgdGhpbmsgbWVtb3J5IGJhcnJpZXJzIGhhdmUgYW55 dGhpbmcgdG8gZG8gd2l0aCBzcGVjdWxhdGlvbiwKPiB0aGV5IGFyZSBhcmNoaXRlY3R1cmFsLgo+ CgpPaCByaWdodC4gTGV0IG1lIGFkZCBhcnJheV9pbmRleF9ub3NwZWMoKSBpbiBuZXh0IHZlcnNp b24uCgpUaGFua3MKCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdApsaW51eC1hcm0ta2VybmVsQGxpc3Rz LmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5m by9saW51eC1hcm0ta2VybmVsCg==