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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 BF765C433DF for ; Mon, 19 Oct 2020 14:19:38 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 DC1CB221FC for ; Mon, 19 Oct 2020 14:19:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="MczSj6+E" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC1CB221FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46972 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kUW0d-0007Qo-Jw for qemu-devel@archiver.kernel.org; Mon, 19 Oct 2020 10:19:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56156) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kUVza-0006xl-D5 for qemu-devel@nongnu.org; Mon, 19 Oct 2020 10:18:30 -0400 Received: from mail-ej1-x644.google.com ([2a00:1450:4864:20::644]:42794) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kUVzU-0003ns-MB for qemu-devel@nongnu.org; Mon, 19 Oct 2020 10:18:29 -0400 Received: by mail-ej1-x644.google.com with SMTP id h24so14149495ejg.9 for ; Mon, 19 Oct 2020 07:18:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=P+q5eYuI1k2apwhrOjSGFGRHo5809gNHaxtenpNMuYw=; b=MczSj6+E+TEhn3EmNgvtfVGUNeTN65ETQn8oj+HFePDmEj2lsrhjWodyiSMAg6RpKT 2+kiYIRLNP0W7O2qdRMjCW+j8weNipZVBX2q9w8Ci4ydrIwmGVgNqm5keZV33N7gjPcu 4QX8jUPxFaXeyD+sox2QMUbhMsg3ugWN8xXzPrqIGiTihy80L44c9ASAqPxF0aC6Yg0I g3SDYH33fDJY6vZHkeHmomE3y5rhd+QXpZYGDTRIgTMKjU4B16EAYnexwX21FgxKrnNa V5f9qD4iVZwbTNSyhruBMB8AUn3Ok8PPqVekpDQmYYu8RMfpp2S1aXfuKcXBZBdPznk8 qQ8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=P+q5eYuI1k2apwhrOjSGFGRHo5809gNHaxtenpNMuYw=; b=lpyEprvcYa6vakdomqs6pFpK/6DQiF1sCp0M8p+KkQFvx4huAti/zfxYBL6JkuPJOz Q6U+zV5Jeyb0j8UMAJrZqDW3qYdgE7z7OXKNxhwKXJjBAG7jySA7a1X+5Pf8NC5lBUEz pLV5wTg7R6S1PzEGM8aXvL26mtGApKqwZ8Oz5xJmVDZMuW9Hbeb9d0Ro0CJn6GYugPid wA/UKB4yHfIR177u2tMgmuAcqkvUqGJfwzrJISa3og2t3Iz+Hh41IXoGlxPe5iZRoV69 ymAEgOaoSPW5IbNg2+wX3kWEreOnohmo1sbFEcuDhj8cgtXegk+sgz2G3oJCZCEa2BPs 8tYg== X-Gm-Message-State: AOAM532Mrv5s2eOkYOaGB/zP6ArXNiWtL173US+SA5IJTQ0AkpWdzMjW 3v2UhRlVqf7tdLU6kAUItFJthnRDdk4soSoxqpzINg== X-Google-Smtp-Source: ABdhPJw3vW4GnAqPbWP30F0VUJ7G6Yt8X9gS2VaxnQj6oSBN9PU9jmUQyfruo6m9TLe6heauDs/6WHB+Df/7MFucyiY= X-Received: by 2002:a17:906:c7d9:: with SMTP id dc25mr110314ejb.482.1603117102813; Mon, 19 Oct 2020 07:18:22 -0700 (PDT) MIME-Version: 1.0 References: <20201015040639.70C6D414009F@webmail.sinamail.sina.com.cn> <7fecfc67da4caab1d677a8b4cd5386b3@kernel.org> <20201015133505.ubxvbrt6xyvl4362@kamzik.brq.redhat.com> <16400df4bdf79b8b22e824eb1a20e2b4@kernel.org> <20201015144104.ytwzpxjlsgyun3ob@kamzik.brq.redhat.com> <20201019092525.ekvgbcwwtm63pueu@kamzik.brq.redhat.com> <20201019113157.GN32292@arm.com> <20201019134043.vqusmzhqp7owjt6x@kamzik.brq.redhat.com> In-Reply-To: <20201019134043.vqusmzhqp7owjt6x@kamzik.brq.redhat.com> From: Peter Maydell Date: Mon, 19 Oct 2020 15:18:11 +0100 Message-ID: Subject: Re: Kernel patch cases qemu live migration failed. To: Andrew Jones Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2a00:1450:4864:20::644; envelope-from=peter.maydell@linaro.org; helo=mail-ej1-x644.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , xu910121@sina.com, Dave Martin , kvmarm , qemu-devel Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 19 Oct 2020 at 14:40, Andrew Jones wrote: > > On Mon, Oct 19, 2020 at 12:43:33PM +0100, Peter Maydell wrote: > > Well, ID regs are special in the architecture -- they always exist > > and must RAZ/WI, even if they're not actually given any fields yet. > > This is different from other "unused" parts of the system register > > encoding space, which UNDEF. > > Table D12-2 confirms the register should be RAZ, as it says the register > is "RO, but RAZ if SVE is not implemented". Does "RO" imply "WI", though? > For the guest we inject an exception on writes, and for userspace we > require the value to be preserved on write. Sorry, I mis-spoke. They're RAZ, but not WI, just RO (which is to say they'll UNDEF if you try to write to them). > I think we should follow the spec, even for userspace access, and be RAZ > for when the feature isn't implemented. As for writes, assuming the > exception injection is what we want for the guest (not WI), then that's > correct. For userspace, I think we should continue forcing preservation > (which will force preservation of zero when it's RAZ). Yes, that sounds right. thanks -- PMM