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 1F9FCC4332F for ; Wed, 1 Nov 2023 11:02:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233043AbjKALC2 (ORCPT ); Wed, 1 Nov 2023 07:02:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231499AbjKALC0 (ORCPT ); Wed, 1 Nov 2023 07:02:26 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65AEFFC; Wed, 1 Nov 2023 04:02:24 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id ffacd0b85a97d-32f8441dfb5so2259928f8f.0; Wed, 01 Nov 2023 04:02:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1698836543; x=1699441343; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:organization:references:cc:to :content-language:subject:reply-to:user-agent:mime-version:date :message-id:from:from:to:cc:subject:date:message-id:reply-to; bh=lLGQwWjL2Aw3sFfyWPVTh2LkEYh2Jo+b78gHIPc7ugc=; b=DBJCW2NsUaqE0lQjq3liJexnkoVaIj4KK0h4KXmguzQSy8anfcloF93TuCrsuT9IPt Fhkg950aQykwX6PBRgzXw5hXphmNo2u1xdGuJ7uxYBvnGHFriLYM5IL+gWdIQOeDcUuz fqcJTO/ilUd6HvlZQfC6LGJp3xtQZURa2mxQbkcpSRzZ9bZd2A50J2yCwJdXal3EmAbg aTk0oh15xTILtIEY3rE4lYLes13o+BOAqyG0oxvXMQ9rYNpmS7Dn5lXZuavuUPrC1QB4 jHKnMP8QW6ndB3y5qT+uLGtPmf4C5piIgb5kdSc3g/jhD84nApD4lgz9iLPt/K8T8/rO VnFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698836543; x=1699441343; h=content-transfer-encoding:in-reply-to:organization:references:cc:to :content-language:subject:reply-to:user-agent:mime-version:date :message-id:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=lLGQwWjL2Aw3sFfyWPVTh2LkEYh2Jo+b78gHIPc7ugc=; b=EdJsOsS/59cJ7Yq+tqMyoVrDdDaODkkTouhNSPCWznd5h98xqrxCR5ZAtU2ScXq4uZ J18YE9hY1osvZ9PF1EYOfTTnYgDOuFWOWq9/agv0LFdz91jA0v2WGybMkKsjGGTViugm NMdVmwI5i3kgC3n5EVkpuv2MHm6pprnUonkJZKx+xY+eNYoFLBsxY86E/fW2roKDeBuc eoMRgwiIvotuhlMTwRheo/JqWaYknpuNI64Iw5qBqzU3qbKH0exOxhiBHkaRcQ3bcgDv UcQJeFSirK3SKYbgaEp3Eeq61SadTSbPMtM164t+qfWF4Xi6vhn7EpDjqijq9k4lvuwz qm4w== X-Gm-Message-State: AOJu0YxLtZewPrG1I+aFFERCPxPBq21bNYM4wYue7DrxG+NyJ+DBF830 v+xjf6Jveba8telt/BFQNBdBo38i9HZ3fA== X-Google-Smtp-Source: AGHT+IGhSCFjWDlSAeyzhKo7ObrQNOoHY2TZnOfL4+qkuskUlpbXSKzRJk8C/Me6qA29voKfgh8GNg== X-Received: by 2002:adf:eb47:0:b0:32c:837e:ef0 with SMTP id u7-20020adfeb47000000b0032c837e0ef0mr11190912wrn.50.1698836542620; Wed, 01 Nov 2023 04:02:22 -0700 (PDT) Received: from [10.95.173.140] (54-240-197-235.amazon.com. [54.240.197.235]) by smtp.gmail.com with ESMTPSA id g8-20020a056000118800b0032f933556b8sm3897074wrx.7.2023.11.01.04.02.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Nov 2023 04:02:22 -0700 (PDT) From: Paul Durrant X-Google-Original-From: Paul Durrant Message-ID: Date: Wed, 1 Nov 2023 11:02:16 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: paul@xen.org Subject: Re: [PATCH v2] KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT Content-Language: en-US To: David Woodhouse , Sean Christopherson Cc: Paolo Bonzini , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20231031115748.622578-1-paul@xen.org> <028f629d16377f9a7e9fd87ef9564846b0ab4ed9.camel@infradead.org> Organization: Xen Project In-Reply-To: <028f629d16377f9a7e9fd87ef9564846b0ab4ed9.camel@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/10/2023 22:48, David Woodhouse wrote: > On Tue, 2023-10-31 at 15:39 -0700, Sean Christopherson wrote: >> On Tue, Oct 31, 2023, Paul Durrant wrote: >>> >>> +       if (force_tsc_unstable) >>> +               guest_hv_clock->flags &= ~PVCLOCK_TSC_STABLE_BIT; >> >> I don't see how this works.  This clears the bit in the guest copy, then clobbers >> all of guest_hv_clock with a memcpy(). > > Agreed, that seems wrong. > It is indeed. Looks like it got moved the wrong side of the memcpy() when I rebased. Paul