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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B8EC4C433F5 for ; Mon, 18 Oct 2021 20:05:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 981566108E for ; Mon, 18 Oct 2021 20:05:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232164AbhJRUH3 (ORCPT ); Mon, 18 Oct 2021 16:07:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230154AbhJRUH1 (ORCPT ); Mon, 18 Oct 2021 16:07:27 -0400 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61D3CC061745 for ; Mon, 18 Oct 2021 13:05:16 -0700 (PDT) Received: by mail-pl1-x629.google.com with SMTP id s1so10229900plg.12 for ; Mon, 18 Oct 2021 13:05:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=gA5NVBhwNW6cB47b6gADEH6G16s82hlNxMBdMQJ46G4=; b=SfaHX5YKldLyP3NtC+ktRQct4C+/GIRlpXxDZ9s68Y0YxnZuS8wh5ZJxfgE0maUIHq lVNuNsueljz7+BSE1iCbBtdSuAszidqeRlOCs6GDsOD+yrp5H/kZVTckts1UOleBYgFs aoVX1xzDWAXh7x4kNe8tGES57oERW9QwogHazvnM5HczEg7pa5/o2H+2lMHr1V50WDV7 jTihlgUATf3SQnWoLqUPQDtkStaUclvHepANzW/z1syaRhicRUHkLTGgOAfreFCVzCK1 tv63MtIYQtAB3ZAh1hS2qHJxFyyuOEPpNgdYr23ZR84YxFNmxX6XZRJXUNaV0JQ4JUqK 8pmg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=gA5NVBhwNW6cB47b6gADEH6G16s82hlNxMBdMQJ46G4=; b=HgSB9TjHd/ephL8Z9Y6h2WOFlyTlVVq+6ASqDYjnULOCAfXgiD0yPPPH1twjao2cKz AGn0/toGxyELev8YiGdOpXjXrjFfHtoMx8RnYr8ZMaDPp69dTEa3rfGh5guXi3DrCFOh DbkYtwgnhEdrrH9J9AiHwqizejQi/9HAWOiyS95SqK/rN8spXakIp7224xEb6hriTkr5 CwvjW+K8+ByXBy3qchqjKgw7o36kSSO7WdkEb9ifAJN0/eSKD6uAuzlOQCFjzcE9GLqf MyIA8tkLKwaaKo13bPk1BtPrNNHA8nhLK0XVJU0igGI1Leoo03xpPRWOM1gEfJsQFo1W QTwQ== X-Gm-Message-State: AOAM532AlGk6g/GKaPS9lBi16OtIu36hZ3LXBen5F8R5s1D/RdJpD7J5 hCWcXdvVoAUo1JZ+KIj6HpOM6g== X-Google-Smtp-Source: ABdhPJwSxbIu5Hn2VcVRe6RKLH//qooKR5tgpTVxwkjGgW2GG1l4y28tCj7bxanZ6i+w3vp1TpVD8g== X-Received: by 2002:a17:90b:4b07:: with SMTP id lx7mr1097565pjb.195.1634587515606; Mon, 18 Oct 2021 13:05:15 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id kb15sm272822pjb.43.2021.10.18.13.05.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Oct 2021 13:05:14 -0700 (PDT) Date: Mon, 18 Oct 2021 20:05:10 +0000 From: Sean Christopherson To: Borislav Petkov Cc: Jane Malalane , LKML , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Pu Wen , Paolo Bonzini , Peter Zijlstra , Andrew Cooper , Yazen Ghannam , Brijesh Singh , Huang Rui , Andy Lutomirski , Kim Phillips , stable@vger.kernel.org Subject: Re: [PATCH v2] x86/cpu: Fix migration safety with X86_BUG_NULL_SEL Message-ID: References: <20211013142230.10129-1-jane.malalane@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 18, 2021, Borislav Petkov wrote: > On Mon, Oct 18, 2021 at 07:29:41PM +0000, Sean Christopherson wrote: > > I agree. If the argument for this patch is that the kernel can be migrated to > > older hardware, then it stands to reason that the kernel could also be migrated > > to a different CPU vendor entirely. E.g. start on Intel, migrate to Zen1, kaboom. > > Migration across vendors? Really, that works? > > I'll believe it only when I see it with my own eyes. There are plenty of caveats, but it is feasible. KVM even has a few patches that came about specifically to support cross-vendor migration, e.g. commit adc2a23734ac ("KVM: nSVM: improve SYSENTER emulation on AMD").