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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03E07C54EE9 for ; Mon, 19 Sep 2022 16:17:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229731AbiISQRU (ORCPT ); Mon, 19 Sep 2022 12:17:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbiISQRQ (ORCPT ); Mon, 19 Sep 2022 12:17:16 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A87713F77 for ; Mon, 19 Sep 2022 09:17:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663604234; h=from:from:reply-to:subject:subject: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=Xn5fnqKtyryYA5w5sfE3wIiUTcmcdDi6qpfcSbkJ4Lw=; b=fL75oB0UK/7xkFg/t9YdFFr3UKA3fT0on11Ga9ay9FnKJC9VzHCNXk0cxwSoSK5iF/mNwu tR58Am+aMuTM1v0HyAjzog/SErZImJawuxLY2I+p6Kaj18+n9uEVrmNfSf8kkgVu7Ty51e ZDe2l0yQ/yDDDt/c6zjsOX1p0DeUYiQ= Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-618-leChdT8yNvqL75bh3tAKCg-1; Mon, 19 Sep 2022 12:17:05 -0400 X-MC-Unique: leChdT8yNvqL75bh3tAKCg-1 Received: by mail-qt1-f197.google.com with SMTP id s21-20020a05622a1a9500b0035bb9e79172so15583993qtc.20 for ; Mon, 19 Sep 2022 09:17:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=Xn5fnqKtyryYA5w5sfE3wIiUTcmcdDi6qpfcSbkJ4Lw=; b=ngLczfNUjJsbZba1+AvaECYriYRFRTMxaDPV7xdvL3lfpFq1fiyteRSs/JLnuVWvrz FeKUT0nXQepS+znELDmHsPKBImoQy1388P4QaEZcSKC7737EQYHLAaeG0NIoNk9EkUYY ATetvYxp0BMMrgcHhfNZ5182zQk4XlQNL3fMrs/d2huHR7gkX6Tu+qN3XCWXy2vUAFDB 71lx1QNkphJn4YLz8dVckmOczjRIBhw2GjNNMSvR5eqWszry8uE4AZk1V9pnsPvAED/+ ItmmXO7xo9WkDk0Bda52SNoM0yMlI0kNhQdUrXAPUUEXBsxsPbaACLVYDh408Ea3XZFw XfFg== X-Gm-Message-State: ACrzQf2wjBcI/+zi/6p2ho1HFhjyYYJt133DnP4NPVE94nNfkCcfYA01 6scovIY/kv8+cX5yWn5cyiWRfxeDExARtVKWxFNGKjjuzvSSgzj09CTl1rliR3rMUCdTmHbFMSl fHS5BwQsUTZO8HNEH4VxGaduG X-Received: by 2002:ac8:5e0a:0:b0:35c:e8d8:6c19 with SMTP id h10-20020ac85e0a000000b0035ce8d86c19mr5068663qtx.178.1663604225349; Mon, 19 Sep 2022 09:17:05 -0700 (PDT) X-Google-Smtp-Source: AMsMyM51+LmYDmB5JjErlr4hYbacMbbiBwggTg81wkAjJVlWGP8agHsUu4S5cY7WS6QJw0cvQ6qJIg== X-Received: by 2002:ac8:5e0a:0:b0:35c:e8d8:6c19 with SMTP id h10-20020ac85e0a000000b0035ce8d86c19mr5068640qtx.178.1663604225144; Mon, 19 Sep 2022 09:17:05 -0700 (PDT) Received: from xz-m1.local (bras-base-aurron9127w-grc-46-70-31-27-79.dsl.bell.ca. [70.31.27.79]) by smtp.gmail.com with ESMTPSA id bv12-20020a05622a0a0c00b0035cf2995ad8sm826570qtb.51.2022.09.19.09.17.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Sep 2022 09:17:04 -0700 (PDT) Date: Mon, 19 Sep 2022 12:17:02 -0400 From: Peter Xu To: Gavin Shan Cc: Marc Zyngier , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-doc@vger.kernel.org, catalin.marinas@arm.com, linux-kselftest@vger.kernel.org, bgardon@google.com, shuah@kernel.org, corbet@lwn.net, drjones@redhat.com, will@kernel.org, zhenyzha@redhat.com, dmatlack@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, oliver.upton@linux.dev, shan.gavin@gmail.com Subject: Re: [PATCH v2 1/5] KVM: x86: Introduce KVM_REQ_RING_SOFT_FULL Message-ID: References: <20220916045135.154505-1-gshan@redhat.com> <20220916045135.154505-2-gshan@redhat.com> <87illlkqfu.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 19, 2022 at 09:58:10AM +1000, Gavin Shan wrote: > I think Marc's explanation makes sense. It won't make difference in terms > of performance. We need to explicitly handle barrier when kvm_test_request() > is used. So I prefer to keep the code if Peter agrees. No strong opinion here. I keep thinking clear+set look awkward even if it's unlikely path to trigger (ring should be recycled when reaching here for any sane user app), but if it's already 2:1 then please go ahead. :) Thanks, -- Peter Xu