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 F1D7CC433EF for ; Mon, 29 Nov 2021 22:52:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236063AbhK2W4D (ORCPT ); Mon, 29 Nov 2021 17:56:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236150AbhK2WzT (ORCPT ); Mon, 29 Nov 2021 17:55:19 -0500 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62939C1A0D1F for ; Mon, 29 Nov 2021 10:36:36 -0800 (PST) Received: by mail-pj1-x102a.google.com with SMTP id j5-20020a17090a318500b001a6c749e697so12240125pjb.1 for ; Mon, 29 Nov 2021 10:36:36 -0800 (PST) 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=tlAzD3aQxZNbhH82DiZEqP09YfqX3PXGzrFEKOt1BUE=; b=VMyEtGnE90jgPkfdArsfFQ73biEKasoDaOcmKYoZKhQrm4TkNFsD5TTOC+i1xSw4IA QwSOEIYqYFet0ZZuJcRlz/K5uFQE/fenSx0d0EnnQ6oZbMNHkjflfqpu20QoV/0Nih3R nMzQUwHTrrLjS0cxhTgTVwhC7ZASBaqm1glT2gMVZ9zfl+0rqU/1lxZr1KBKehahtfy9 cXLL/bvyEMQd0qujLL/xmH/ESnBM3510+1Nuicl2fKEThRU8WVOA8JCJKg3STPnXD26P DDqxVmJCx2aXGJ6DArW+HHKb8MeCVbRgGp2m7sZZjJfZ78gCHNoKusXy9dix+Y0oTbAR QSXA== 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=tlAzD3aQxZNbhH82DiZEqP09YfqX3PXGzrFEKOt1BUE=; b=gN/HWKT82a1jY8wCnEe3PbjCI2tIPnpdCsuF/jzRIEg0+e7axIQrzcxGgqBa2OUIRd vFqHNqDXMx7iyJx3hcKpYnT4apqyUxJpb/wa4Z3eOdh5oKlCtqlqCp+YY83Ea3l7reSF qkA8XhhWip+VCj3TCoR6LTKMhVw92gykyOuuIEsamC7MAPfQ1lviyVmPs67YRgKASete B0vVg7O8DtOM09OQORGG+kTWaJwHhHiKDVF9tdcEk22mJfEuPQhzE4bSMWS59DBkla3n m7kfKOMjDToOykoqq25W0GNw5bzAGxrAASFWkdcfr19v8SgAJexlWtYKwsmeNzlA7KG7 MDpA== X-Gm-Message-State: AOAM5320kxDovq1r/jgp7gthoXOc1Kxr8djzqkxCu65JKmhZJGT53asi J4Gh4dPJDrkD1lUaz2TlSClDKw== X-Google-Smtp-Source: ABdhPJx8WtPK3FSjNprjLl/l1toByBy/n2qpSmC6t2XTOO85rqwFTlV9d2tAz2CyzikyPU9sLpNeRg== X-Received: by 2002:a17:902:aa43:b0:143:e20b:f37f with SMTP id c3-20020a170902aa4300b00143e20bf37fmr61456504plr.65.1638210995742; Mon, 29 Nov 2021 10:36:35 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id 95sm62436pjo.2.2021.11.29.10.36.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Nov 2021 10:36:35 -0800 (PST) Date: Mon, 29 Nov 2021 18:36:31 +0000 From: Sean Christopherson To: Thomas Gleixner Cc: isaku.yamahata@intel.com, Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , erdemaktas@google.com, Connor Kuehl , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, isaku.yamahata@gmail.com, Sean Christopherson , Xiaoyao Li Subject: Re: [RFC PATCH v3 47/59] KVM: TDX: Define TDCALL exit reason Message-ID: References: <87k0gwhttc.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k0gwhttc.ffs@tglx> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 25, 2021, Thomas Gleixner wrote: > On Wed, Nov 24 2021 at 16:20, isaku yamahata wrote: > > From: Sean Christopherson > > > > Define the TDCALL exit reason, which is carved out from the VMX exit > > reason namespace as the TDCALL exit from TDX guest to TDX-SEAM is really > > just a VM-Exit. > > How is this carved out? What's the value of this word salad? > > It's simply a new exit reason. Not more, not less. So what? The changelog is alluding to the fact that KVM should never directly see a TDCALL VM-Exit. For TDX, KVM deals only with "returns" from the TDX-Module. The "carved out" bit is calling out that the transition from SEAM Non-Root (the TDX guest) to SEAM Root (the TDX Module) is actually a VT-x/VMX VM-Exit, e.g. if TDX were somehow implemented without relying on VT-x/VMX, then the TDCALL exit reason wouldn't exist. > > Co-developed-by: Xiaoyao Li > > Signed-off-by: Xiaoyao Li > > Signed-off-by: Sean Christopherson > > I'm pretty sure that it does not take two engineers to add a new exit > reason define, but it takes at least two engineers to come up with a > convoluted explanation for it. Nah, just one ;-)