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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id m19sm484596edd.38.2021.08.13.03.44.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Aug 2021 03:44:27 -0700 (PDT) Subject: Re: [PATCH v6 01/21] KVM: x86: Fix potential race in KVM_GET_CLOCK To: Oliver Upton Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Andrew Jones , Will Deacon , Catalin Marinas References: <20210804085819.846610-1-oupton@google.com> <20210804085819.846610-2-oupton@google.com> <78eeaf83-2bfa-8452-1301-a607fba7fa0c@redhat.com> From: Paolo Bonzini Message-ID: <0b415872-7a67-d38b-ae01-62c38b365be0@redhat.com> Date: Fri, 13 Aug 2021 12:44:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 13/08/21 12:39, Oliver Upton wrote: > Might it make sense to fix this issue under the existing locking > scheme, then shift to what you're proposing? I say that, but the > locking change in 03/21 would most certainly have a short lifetime > until this patch supersedes it. Yes, definitely. The seqcount change would definitely go in much later. Extracting KVM_{GET,SET}_CLOCK to separate function would also be a patch of its own. Give me a few more days of frantic KVM Forum preparation. :) Paolo 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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, 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 E3F58C4338F for ; Fri, 13 Aug 2021 10:44:37 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 5D1AB610CC for ; Fri, 13 Aug 2021 10:44:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5D1AB610CC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B806D4020A; Fri, 13 Aug 2021 06:44:36 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@redhat.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id kGGgoE1V7RZC; Fri, 13 Aug 2021 06:44:32 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D0F024086D; Fri, 13 Aug 2021 06:44:32 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 356AA4029F for ; Fri, 13 Aug 2021 06:44:32 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id C6NwLf7CiPIv for ; Fri, 13 Aug 2021 06:44:31 -0400 (EDT) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 53B5B4020A for ; Fri, 13 Aug 2021 06:44:31 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628851471; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CCRKNaL8rUMbzILuCY+AB0BP3lwlD4VuYd7MDG+p8TM=; b=XgVZGXYYGNr1GMR4AMqNeGXB0sdMy1O9Zxt343adCz4JJYmafc9+qzKjld8shxomEALTS1 xposwu/QJXiPDkr1ZWzY8rpePhQdBtYhWrcD23rdgEpdgGNoW9ocLV7v817EiptkO49JL4 UfEhAwzwwi3qW0Kti2IzU3/bEi8DwJk= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-92-BfUwsVV0Nt-PJBZky89BSA-1; Fri, 13 Aug 2021 06:44:29 -0400 X-MC-Unique: BfUwsVV0Nt-PJBZky89BSA-1 Received: by mail-ed1-f70.google.com with SMTP id p2-20020a50c9420000b02903a12bbba1ebso4653596edh.6 for ; Fri, 13 Aug 2021 03:44:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=CCRKNaL8rUMbzILuCY+AB0BP3lwlD4VuYd7MDG+p8TM=; b=IcP3Gxz8M3JI/ehxHdj06kUfibw2MhQTCEegnViRKpbA1VV7bxZZ8/8/yfdOnbSJUa 0dTzONzRol7WZb6Mxtb5oHVD9fb9DyQgVjeGZP43CpTccwwJoLD5ks2fTgQTRzOQPCWi d8ZgRXS9s682/hsJEYm8SGruAoz29Oo4MbGobMJR37tyRLT5qvgEdh58OZjZqlEINHu6 8bvIKVZlxlf78pCiErbtuZ7dc6u+qEXUq0XHljz0zvxbGp/GroJI7wNFRuUDhgqHnN0R cFru3BbN+EAiaZLetOvoFPgSPhvaiCUYsb69NHB+sGz0/JMtZUNrI9SwOgDrLl+Yqpr0 kP2g== X-Gm-Message-State: AOAM530uLYN7qWLUQXV5HzD/j4o7gkWXdUytUV5vm2dRbnQtd451OCS3 TMBCi+eC8WiuQYbTsIV4sTi6nrqybApZgA0bjx2J1osLOdK+BuQTsBvVPJ0MewaG/DjqYeImVio xdF6HuIjlbniSwA8YkNm1bAGt X-Received: by 2002:a17:906:6b0c:: with SMTP id q12mr141885ejr.0.1628851468596; Fri, 13 Aug 2021 03:44:28 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzbOi0KwA+drc3M+Egn5GSdsceHGVvGcEGdWBkM4ljas5GpNbvsJOOdudbDSGWUVsAACOZz2w== X-Received: by 2002:a17:906:6b0c:: with SMTP id q12mr141872ejr.0.1628851468394; Fri, 13 Aug 2021 03:44:28 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id m19sm484596edd.38.2021.08.13.03.44.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Aug 2021 03:44:27 -0700 (PDT) Subject: Re: [PATCH v6 01/21] KVM: x86: Fix potential race in KVM_GET_CLOCK To: Oliver Upton References: <20210804085819.846610-1-oupton@google.com> <20210804085819.846610-2-oupton@google.com> <78eeaf83-2bfa-8452-1301-a607fba7fa0c@redhat.com> From: Paolo Bonzini Message-ID: <0b415872-7a67-d38b-ae01-62c38b365be0@redhat.com> Date: Fri, 13 Aug 2021 12:44:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Cc: Catalin Marinas , kvm@vger.kernel.org, Will Deacon , Sean Christopherson , Raghavendra Rao Anata , Peter Shier , Marc Zyngier , David Matlack , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Jim Mattson 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 13/08/21 12:39, Oliver Upton wrote: > Might it make sense to fix this issue under the existing locking > scheme, then shift to what you're proposing? I say that, but the > locking change in 03/21 would most certainly have a short lifetime > until this patch supersedes it. Yes, definitely. The seqcount change would definitely go in much later. Extracting KVM_{GET,SET}_CLOCK to separate function would also be a patch of its own. Give me a few more days of frantic KVM Forum preparation. :) Paolo _______________________________________________ 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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 450ACC4320A for ; Fri, 13 Aug 2021 10:46:57 +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 12A976104F for ; Fri, 13 Aug 2021 10:46:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 12A976104F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ono3u88tQajzkqyCf3bZxHb3cAumPZcGshhzl1rKaYI=; b=aawR9XVTJaFVDU8d3B1WtrNAue teoKPgWsMJvr4S9uSDbLtd0qjyDYaTGkQRAUj1aoLQ7YaYEFDHA7Cwf1Kt7wpJrllHqalFpvpXPey K+XWVgS+JMzCJf6zzggDP1lfYQ1u9Kr3i/n5zA5dqgjhrpQQITqFBPW8XCMjf3q1OKQLatC8v2qDv +5p700h3lWCH24JniwPXw8w4vn3aAFIJmuW2UD/bWu9oDWLfJnzA1U4n6lx/GvhL4kWeYbVMyzd6w KTvZ8xxVfEtfcq7moDLrVTqI9Ff1d03tjFMwxREB5de6LaRddsNppodiKd8RjdbSirwQKczDODERo 0Mcsf77A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEUg2-00CTr3-E4; Fri, 13 Aug 2021 10:44:38 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mEUfw-00CTpn-3V for linux-arm-kernel@lists.infradead.org; Fri, 13 Aug 2021 10:44:34 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628851471; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CCRKNaL8rUMbzILuCY+AB0BP3lwlD4VuYd7MDG+p8TM=; b=XgVZGXYYGNr1GMR4AMqNeGXB0sdMy1O9Zxt343adCz4JJYmafc9+qzKjld8shxomEALTS1 xposwu/QJXiPDkr1ZWzY8rpePhQdBtYhWrcD23rdgEpdgGNoW9ocLV7v817EiptkO49JL4 UfEhAwzwwi3qW0Kti2IzU3/bEi8DwJk= Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-288-HRIcyXISMcaHzE_4YQqRug-1; Fri, 13 Aug 2021 06:44:29 -0400 X-MC-Unique: HRIcyXISMcaHzE_4YQqRug-1 Received: by mail-ej1-f72.google.com with SMTP id zp23-20020a17090684f7b02905a13980d522so2796101ejb.2 for ; Fri, 13 Aug 2021 03:44:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=CCRKNaL8rUMbzILuCY+AB0BP3lwlD4VuYd7MDG+p8TM=; b=hOxA6vo45pUZHCMU16Msg7g8lRNtIo0p3EkaMTPl963RLau0mYLkbrjE6CtO8TKrAy p7Nt6j4IRRJBG63E9eW1oabiLf3Vw2pGFfz3cK11l/giA1kLRE883a6aDRJqSwDrHDjF s5GXq3ZM8opVK++OZ4T5FRKI/E4wgf6+yPuf1g+6MY48Ku/QwKMNAwHx+FZ4UExgC6xY h4OwccFTVNlbUyWrXeqAfNolMNgE+aEQw167g1Nwg5o+Cg04m6IEiDSAyiUZwtycB8vJ fYA2wal/oayx6xE2l8MbO0tKYbUjBYtyM9TWORgnzK0n1XAyO2eR5yRuy2o+DeuQ/ISx cyXw== X-Gm-Message-State: AOAM531T0cBgdbew98XsINguQ5QvMRnJM6igDkHXKBkwOMjtCaXY7Ojr 6CKEm20jiZVoSzhVZb3KI8fkGq0CaetnUdnnZREswn+Z5MQk+TXut8we5S9vsAYWdWoqKLDHMqY ZNuYJwZ8T4HZdVaccMq694Q+S6zXCium8h/A= X-Received: by 2002:a17:906:6b0c:: with SMTP id q12mr141889ejr.0.1628851468596; Fri, 13 Aug 2021 03:44:28 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzbOi0KwA+drc3M+Egn5GSdsceHGVvGcEGdWBkM4ljas5GpNbvsJOOdudbDSGWUVsAACOZz2w== X-Received: by 2002:a17:906:6b0c:: with SMTP id q12mr141872ejr.0.1628851468394; Fri, 13 Aug 2021 03:44:28 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id m19sm484596edd.38.2021.08.13.03.44.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Aug 2021 03:44:27 -0700 (PDT) Subject: Re: [PATCH v6 01/21] KVM: x86: Fix potential race in KVM_GET_CLOCK To: Oliver Upton Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Andrew Jones , Will Deacon , Catalin Marinas References: <20210804085819.846610-1-oupton@google.com> <20210804085819.846610-2-oupton@google.com> <78eeaf83-2bfa-8452-1301-a607fba7fa0c@redhat.com> From: Paolo Bonzini Message-ID: <0b415872-7a67-d38b-ae01-62c38b365be0@redhat.com> Date: Fri, 13 Aug 2021 12:44:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210813_034432_306844_510AEBCE X-CRM114-Status: GOOD ( 11.80 ) 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 13/08/21 12:39, Oliver Upton wrote: > Might it make sense to fix this issue under the existing locking > scheme, then shift to what you're proposing? I say that, but the > locking change in 03/21 would most certainly have a short lifetime > until this patch supersedes it. Yes, definitely. The seqcount change would definitely go in much later. Extracting KVM_{GET,SET}_CLOCK to separate function would also be a patch of its own. Give me a few more days of frantic KVM Forum preparation. :) Paolo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel