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 5E129C4167B for ; Thu, 30 Nov 2023 15:49:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346407AbjK3PtJ (ORCPT ); Thu, 30 Nov 2023 10:49:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232208AbjK3PtH (ORCPT ); Thu, 30 Nov 2023 10:49:07 -0500 Received: from mail-wm1-x32f.google.com (mail-wm1-x32f.google.com [IPv6:2a00:1450:4864:20::32f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3A46C1; Thu, 30 Nov 2023 07:49:13 -0800 (PST) Received: by mail-wm1-x32f.google.com with SMTP id 5b1f17b1804b1-40859dee28cso9262135e9.0; Thu, 30 Nov 2023 07:49:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701359352; x=1701964152; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:organization:references:to :content-language:subject:reply-to:user-agent:mime-version:date :message-id:from:from:to:cc:subject:date:message-id:reply-to; bh=G8ImaGSq+yK32uci9kQ8gJDa7ZpsaoeN49Mmc0aXtG4=; b=LOgMPLvSO1wo4/NWXGQZLGa4gzMaod1ajDjN+AmhtWIXIKpJHHvBjj8jbSPaB3tOzo /y3Ak0CFwbpbbdM5crV7IYCTBGVxAaF5k34D1akQP1svwIrVGbzZd99uJGVa7MXfymg3 UoNVcI7kVuajnNwMwDMVAsdvKsJDIlNL5CfGtVkC6r4pDXtuJmIZuKkmGN+SJ0ehHXx1 hm6zpGOF8bCgav8wIDIraFjRBiTR3bhoDmOYKLknmszvYi3TX0x+An+uOjdXtaDKjNB+ OK8LmHyZ15Ko6GHTPxx0ZXEu+q+/dw+lEjjRw81mXmEa78qAjAwAWb83kJDENfPVsHub NfQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701359352; x=1701964152; h=content-transfer-encoding:in-reply-to:organization:references: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=G8ImaGSq+yK32uci9kQ8gJDa7ZpsaoeN49Mmc0aXtG4=; b=XizxQv0PLD9oUNACzbjz/j+Z7dAVcX0CPxiLOWT81vTbeS7fNCiAwbuwbVQg+R0kQJ 3kb0GFKCfSxU4qZQ+DP/2toX2onBLSMh4AameX243danvUi+gAhokavdBV7rMWdaAmKg GCYulJJXyJi9+ylX+jw+S5z6HrIPn5r/u7zckvALcaQzIqbJGtOyClOVnlsZnB/qbryj 9KcueSJs2uDV5/CWu3y+cOEnHNXNefJh5J6k12BDOXS7fd4SyLJ4AZNWS4JLTpCjYzQK C+GHYry7Ux8DrjLTT0kMHcN/E106iaT4FQlK8qUVmXmIGEKxzWvzDBx63zpab4hT0uZe uKqw== X-Gm-Message-State: AOJu0YxxSUBj0wUfj0MfCuhoh1AnHnN+EF1y7CICkdtCC5jP0V5dgvTZ myzkNltGlgPH7yje1DmXqScYL+tNni0ucMOF X-Google-Smtp-Source: AGHT+IEB9DPksNcsSDJF+gYbx+4U10uRUhKK0tMFC5I8x3MPbxcI5/dtvTBLoAnKpdVt/viAq1hJTw== X-Received: by 2002:adf:f985:0:b0:332:c9be:d9bd with SMTP id f5-20020adff985000000b00332c9bed9bdmr14938111wrr.45.1701359351919; Thu, 30 Nov 2023 07:49:11 -0800 (PST) Received: from [192.168.17.228] (54-240-197-239.amazon.com. [54.240.197.239]) by smtp.gmail.com with ESMTPSA id d9-20020a056000114900b00332e8dd713fsm1846302wrx.74.2023.11.30.07.49.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Nov 2023 07:49:11 -0800 (PST) From: Paul Durrant X-Google-Original-From: Paul Durrant Message-ID: Date: Thu, 30 Nov 2023 15:49:07 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: paul@xen.org Subject: Re: [PATCH v5] KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT Content-Language: en-US To: David Woodhouse , 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, Sean Christopherson References: <20231102162128.2353459-1-paul@xen.org> <356a88e424a58990a1b83afa719662e75f42bf98.camel@infradead.org> Organization: Xen Project In-Reply-To: <356a88e424a58990a1b83afa719662e75f42bf98.camel@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/11/2023 18:39, David Woodhouse wrote: > On Thu, 2023-11-02 at 16:21 +0000, Paul Durrant wrote: >> From: Paul Durrant >> >> Unless explicitly told to do so (by passing 'clocksource=tsc' and >> 'tsc=stable:socket', and then jumping through some hoops concerning >> potential CPU hotplug) Xen will never use TSC as its clocksource. >> Hence, by default, a Xen guest will not see PVCLOCK_TSC_STABLE_BIT set >> in either the primary or secondary pvclock memory areas. This has >> led to bugs in some guest kernels which only become evident if >> PVCLOCK_TSC_STABLE_BIT *is* set in the pvclocks. Hence, to support >> such guests, give the VMM a new Xen HVM config flag to tell KVM to >> forcibly clear the bit in the Xen pvclocks. >> >> Signed-off-by: Paul Durrant > > Reviewed-by: David Woodhouse Sean, Is any more work needed on this? Paul