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[35.233.69.230]) by smtp.gmail.com with ESMTPSA id j30sm28608530wrj.62.2021.03.17.07.47.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Mar 2021 07:47:27 -0700 (PDT) Date: Wed, 17 Mar 2021 14:47:25 +0000 From: Quentin Perret To: Marc Zyngier Subject: Re: [PATCH 1/2] KVM: arm64: Introduce KVM_PGTABLE_S2_NOFWB Stage-2 flag Message-ID: References: <20210315143536.214621-34-qperret@google.com> <20210317141714.383046-1-qperret@google.com> <20210317141714.383046-2-qperret@google.com> <87a6r1j10k.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87a6r1j10k.wl-maz@kernel.org> Cc: kernel-team@android.com, android-kvm@google.com, catalin.marinas@arm.com, mate.toth-pal@arm.com, tabba@google.com, linux-kernel@vger.kernel.org, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org, seanjc@google.com, will@kernel.org, kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Wednesday 17 Mar 2021 at 14:41:31 (+0000), Marc Zyngier wrote: > Hi Quentin, > > On Wed, 17 Mar 2021 14:17:13 +0000, > Quentin Perret wrote: > > > > In order to further configure stage-2 page-tables, pass flags to the > > init function using a new enum. > > > > The first of these flags allows to disable FWB even if the hardware > > supports it as we will need to do so for the host stage-2. > > > > Signed-off-by: Quentin Perret > > > > --- > > > > One question is, do we want to use stage2_has_fwb() everywhere, including > > guest-specific paths (e.g. kvm_arch_prepare_memory_region(), ...) ? > > > > That'd make this patch more intrusive, but would make the whole codebase > > work with FWB enabled on a guest by guest basis. I don't see us use that > > anytime soon (other than maybe debug of some sort?) but it'd be good to > > have an agreement. > > I'm not sure how useful that would be. We fought long and hard to get > FWB, and I can't see a good reason to disable it for guests unless the > HW was buggy (but in which case that'd be for everyone). I'd rather > keep the changes small for now (this whole series is invasive > enough!). OK, that works for me. > As for this patch, I only have a few cosmetic comments: Happy with the suggestions, I'll fold that in v6. Cheers, Quentin _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C40FCC433E6 for ; Wed, 17 Mar 2021 14:49:43 +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 8AA0764EF9 for ; Wed, 17 Mar 2021 14:49:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8AA0764EF9 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.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-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=3VU7YuGeyaPlDFDnV9X6vmWWJb5QOe9rxAMuG65+mSU=; b=Kh4FE0gNEe3/+8rPqKyQIudDA wkqR/3Zd3mLYEdFEUc8uAQu6UYCkLVZlGblXHA3Bg5kfh+DuNzqAWYjZj/q65yBP+oropbQ/8AAt9 6hrqC3f1QnFTIQi2E558DsBHQbWvcm/6wZ9iF0XoelJk2AOBee2R09zLn+ypgU8a9dmvsvjzlhi/X B0R5nlQA5GFIiE04zoBYHVqOnjduhezfh+spyyvggLPmfmavWNeBCz2UOLPEnQqt1Zyll2bVdEKW8 SXk9gthi4J+82ocjKrD+KTXik5q0pjvIJSf+4t4xbna4c+EVpgKewavsPoy5/pp77gjm5VOgkaddD lskQCT0eQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lMXSU-003Lk1-KO; Wed, 17 Mar 2021 14:47:39 +0000 Received: from mail-wm1-x336.google.com ([2a00:1450:4864:20::336]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lMXSL-003LgX-39 for linux-arm-kernel@lists.infradead.org; Wed, 17 Mar 2021 14:47:33 +0000 Received: by mail-wm1-x336.google.com with SMTP id r15-20020a05600c35cfb029010e639ca09eso3541239wmq.1 for ; Wed, 17 Mar 2021 07:47:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=+NAwyApKGr9OeZM13UJcb083CY8RcBRmmL5kmNSORk4=; b=nxH0ZK/Z7SqIpebv2BlNzbvBvCRL5tEEruzMTQdpRepI5rsoy3EZLK4EEJC1LcX9fX sZHM/Q8lK2uJl//w+rXeQthlNb61MBnMXN+zTp3nVHigR4jyXmNOpaYn1UZU/71AiA3r v9ekQg3b1cv3QMlWeD+X3BlwdAHitT4uZAQtmtPYGdS9FEWzy9arlQ4fD01OFvaj/LXh spWFU8d78nqCj04AcACb3fE1uwwa0MLw3TYG8DZpJtf5IZkwn9yxoH/faccSN+wTUWf4 2RDQfbmbFAKdXhc/jkyDlWHxa02Mv3hAk5WA1xczlUSB/2fqQrovbN795fJIbS1Y3Pjv wZyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=+NAwyApKGr9OeZM13UJcb083CY8RcBRmmL5kmNSORk4=; b=tI749pRO3TamMFNltsI0VlVuQQjeKRlGC1/EwoOIBJaVABJIV7K4Ld6vTnh3qgUrha FT+O/YVI0O4/iRlZopvFRqAj94DsDMPk6VyB9vM6JMOj8y4nsGIA/01eMBJu/bEKp6gT MOVgYGTwwD6PuhhWByIAhytTeg8EB0A1ooO1dY5HSpgdc9oSeqXzGyRl1O32prc848Kz ktzRpllSTNRCC86+vWGBTz6QLfl/FE/f2AfNCmxCD+JxFjVvNiNc8UgYrabOJYytIgIS WHx96dHuCTRJudZDWHwNHVcpVKyLfYgVYq13JZvghQNbRGLg1mL7PqYXTBqMtR9ehA44 aGeA== X-Gm-Message-State: AOAM530ljZA58j9QGtQDuQz5o1u7dDqjcNUzslRNUPdB4TuOL0Vqds8Q GArYLpQ6mu8Xkf/+M1h1DeQcqg== X-Google-Smtp-Source: ABdhPJx6AfATlLEiTNGqh1ucC7Hd3kT3uV12yFJvjNGYlQxmEPb67BtfUEuJl/OZaTdbQtSNc86AuA== X-Received: by 2002:a7b:c5c7:: with SMTP id n7mr4102199wmk.30.1615992448272; Wed, 17 Mar 2021 07:47:28 -0700 (PDT) Received: from google.com (230.69.233.35.bc.googleusercontent.com. [35.233.69.230]) by smtp.gmail.com with ESMTPSA id j30sm28608530wrj.62.2021.03.17.07.47.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Mar 2021 07:47:27 -0700 (PDT) Date: Wed, 17 Mar 2021 14:47:25 +0000 From: Quentin Perret To: Marc Zyngier Cc: catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, android-kvm@google.com, seanjc@google.com, linux-kernel@vger.kernel.org, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, tabba@google.com, ardb@kernel.org, mark.rutland@arm.com, dbrazdil@google.com, mate.toth-pal@arm.com Subject: Re: [PATCH 1/2] KVM: arm64: Introduce KVM_PGTABLE_S2_NOFWB Stage-2 flag Message-ID: References: <20210315143536.214621-34-qperret@google.com> <20210317141714.383046-1-qperret@google.com> <20210317141714.383046-2-qperret@google.com> <87a6r1j10k.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87a6r1j10k.wl-maz@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210317_144731_129403_59B4F674 X-CRM114-Status: GOOD ( 23.22 ) 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: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wednesday 17 Mar 2021 at 14:41:31 (+0000), Marc Zyngier wrote: > Hi Quentin, > > On Wed, 17 Mar 2021 14:17:13 +0000, > Quentin Perret wrote: > > > > In order to further configure stage-2 page-tables, pass flags to the > > init function using a new enum. > > > > The first of these flags allows to disable FWB even if the hardware > > supports it as we will need to do so for the host stage-2. > > > > Signed-off-by: Quentin Perret > > > > --- > > > > One question is, do we want to use stage2_has_fwb() everywhere, including > > guest-specific paths (e.g. kvm_arch_prepare_memory_region(), ...) ? > > > > That'd make this patch more intrusive, but would make the whole codebase > > work with FWB enabled on a guest by guest basis. I don't see us use that > > anytime soon (other than maybe debug of some sort?) but it'd be good to > > have an agreement. > > I'm not sure how useful that would be. We fought long and hard to get > FWB, and I can't see a good reason to disable it for guests unless the > HW was buggy (but in which case that'd be for everyone). I'd rather > keep the changes small for now (this whole series is invasive > enough!). OK, that works for me. > As for this patch, I only have a few cosmetic comments: Happy with the suggestions, I'll fold that in v6. Cheers, Quentin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 186D5C433DB for ; Wed, 17 Mar 2021 14:48:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C474364F50 for ; Wed, 17 Mar 2021 14:48:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231858AbhCQOr5 (ORCPT ); Wed, 17 Mar 2021 10:47:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231184AbhCQOra (ORCPT ); Wed, 17 Mar 2021 10:47:30 -0400 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96D72C06174A for ; Wed, 17 Mar 2021 07:47:29 -0700 (PDT) Received: by mail-wm1-x32b.google.com with SMTP id m20-20020a7bcb940000b029010cab7e5a9fso3525117wmi.3 for ; Wed, 17 Mar 2021 07:47:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=+NAwyApKGr9OeZM13UJcb083CY8RcBRmmL5kmNSORk4=; b=nxH0ZK/Z7SqIpebv2BlNzbvBvCRL5tEEruzMTQdpRepI5rsoy3EZLK4EEJC1LcX9fX sZHM/Q8lK2uJl//w+rXeQthlNb61MBnMXN+zTp3nVHigR4jyXmNOpaYn1UZU/71AiA3r v9ekQg3b1cv3QMlWeD+X3BlwdAHitT4uZAQtmtPYGdS9FEWzy9arlQ4fD01OFvaj/LXh spWFU8d78nqCj04AcACb3fE1uwwa0MLw3TYG8DZpJtf5IZkwn9yxoH/faccSN+wTUWf4 2RDQfbmbFAKdXhc/jkyDlWHxa02Mv3hAk5WA1xczlUSB/2fqQrovbN795fJIbS1Y3Pjv wZyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=+NAwyApKGr9OeZM13UJcb083CY8RcBRmmL5kmNSORk4=; b=YDyzJu5uoAGwQbylR5mwQHuJtaMyfbmXj/WeD1t6yZCBBAdQTRXts6pOtTr7jWmmin pa1y6nbQCvDPW7wkgxaTZq0tf7RyRfK3IhVTvMt58MMnjP44sG0Tsl5dzXkygB1j8C5W dwkXg3m5Sd7IpTs0mCpO1ymyTvfRfM0M8B8Iw/tC8fCnVgDfolJSkUOI8YWPjTQV+ntG 6NuVW0dF/IsBf0NmvT9HLPwsoEJh1z3QYTrYLm6a+heHhkfGb5H5zkLmitCaN63ftRI9 uoLXzYiDOK5ou8ARnsrGHD2ysF7iD3SLmlBglVfgGe60k9N3z2ZiLWPmd0/Q1TexTe4o 5v/A== X-Gm-Message-State: AOAM533P1DDuuAvnE1uy7x1r1k2iI9LHHF++tizJ/gfjMHJxkzsKKOIA H3SD9Mplg9J3kykWDuYxzyPiAA== X-Google-Smtp-Source: ABdhPJx6AfATlLEiTNGqh1ucC7Hd3kT3uV12yFJvjNGYlQxmEPb67BtfUEuJl/OZaTdbQtSNc86AuA== X-Received: by 2002:a7b:c5c7:: with SMTP id n7mr4102199wmk.30.1615992448272; Wed, 17 Mar 2021 07:47:28 -0700 (PDT) Received: from google.com (230.69.233.35.bc.googleusercontent.com. [35.233.69.230]) by smtp.gmail.com with ESMTPSA id j30sm28608530wrj.62.2021.03.17.07.47.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Mar 2021 07:47:27 -0700 (PDT) Date: Wed, 17 Mar 2021 14:47:25 +0000 From: Quentin Perret To: Marc Zyngier Cc: catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, android-kvm@google.com, seanjc@google.com, linux-kernel@vger.kernel.org, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, tabba@google.com, ardb@kernel.org, mark.rutland@arm.com, dbrazdil@google.com, mate.toth-pal@arm.com Subject: Re: [PATCH 1/2] KVM: arm64: Introduce KVM_PGTABLE_S2_NOFWB Stage-2 flag Message-ID: References: <20210315143536.214621-34-qperret@google.com> <20210317141714.383046-1-qperret@google.com> <20210317141714.383046-2-qperret@google.com> <87a6r1j10k.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87a6r1j10k.wl-maz@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 17 Mar 2021 at 14:41:31 (+0000), Marc Zyngier wrote: > Hi Quentin, > > On Wed, 17 Mar 2021 14:17:13 +0000, > Quentin Perret wrote: > > > > In order to further configure stage-2 page-tables, pass flags to the > > init function using a new enum. > > > > The first of these flags allows to disable FWB even if the hardware > > supports it as we will need to do so for the host stage-2. > > > > Signed-off-by: Quentin Perret > > > > --- > > > > One question is, do we want to use stage2_has_fwb() everywhere, including > > guest-specific paths (e.g. kvm_arch_prepare_memory_region(), ...) ? > > > > That'd make this patch more intrusive, but would make the whole codebase > > work with FWB enabled on a guest by guest basis. I don't see us use that > > anytime soon (other than maybe debug of some sort?) but it'd be good to > > have an agreement. > > I'm not sure how useful that would be. We fought long and hard to get > FWB, and I can't see a good reason to disable it for guests unless the > HW was buggy (but in which case that'd be for everyone). I'd rather > keep the changes small for now (this whole series is invasive > enough!). OK, that works for me. > As for this patch, I only have a few cosmetic comments: Happy with the suggestions, I'll fold that in v6. Cheers, Quentin