From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 71F8639C001; Mon, 23 Mar 2026 12:17:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774268255; cv=none; b=s+iKLdQsMv9BpAsvRUaASaKbmmp2OBwVlBG90RfuAoZ3+rnny6e+muR3gNhiRYujQtE4t4N7jcZlFxqnK3Zz9RJhFxQn7RBSZAxA13wz2LJNuyE1mJP1mlcpPUDV6fG+pV144oXpDY/trTwRxJr4r+FBVFblH5qjuSDlb5C3o1Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774268255; c=relaxed/simple; bh=2o9t91MAFkEEC33gJK2BYO/b2oCktQ5ZVRUEjJeP8Zw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dewwr0gFVhO2AnD5FEbkyRpNlNL8Q71mZJyWUfvIT1QlpxDtamR5BKUZVdHLNv7qQvCerRadcEJJi+sS2PYrOKe2fEUgA6TjFH3JVDfA/JVoZAG2lztCq4qTzjZDxdBkGndPbHL5Z9Md7bkKVPKrOeGZLYJKuMtXzINESKD6yW8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=Sg9ithsY; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="Sg9ithsY" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 80A3040E019D; Mon, 23 Mar 2026 12:17:28 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id ELMIRdKi8huZ; Mon, 23 Mar 2026 12:17:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1774268244; bh=f738n672SoV7BVsc9oVqYhfWXfRA4kWj+hTcFk69Th4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Sg9ithsYbaS952b3lKr4QIpqjR5Z6xSJA+S+Fgv1dDR93sv5j/GtHSV+gqdlNVdeI JevPbyz3diPKaL5Cf34yLUZq0lbIrLT/s+ku9HjSbSFOftOf3dH8gqyq4PR+irWUDx 2m/NItVJ4vGJ6jYA/YYFXnVAO5k9ehwrlRDmh5vZKfsvgbrQ3m+aXNc2qNDWHlNY/E ZavgEuzz7j6M8UJ5N696oa0IGtH76JAuStf0Vg6PBkpCxL48YgPOMEo8yf0A0dEq8v 5ZYmmj6g/GwB5I6fOGGxFd2L97tFWtk7tGLrrIfeWfgHYXY0ZF+uX8UdbzVfHfx0eX Lyac1tBMJM2hWbqB+KzFdeE64ZFjIg9kAVAvpEl098DqFiAoaXOcgH4V8FLMuk41EH qxvpBhgtDD7F41ssl6VvVw7nuh/xpTj+TKtV2WopFrTHtPM5r8uCteM69DJdxzoZgq TxCqhn9rcZGtGe+uervtNN1ueizekHLhePZi2zNs1Sz1RT29EjSo++pHLK+pzbk4R8 h7iqZHlHyQAJjR63PflEdjlSh3Ddyp1D74CY3on+3e8z0/BDqIqbIloRdSPZvKUYm0 c0IASD9FMdXlev6+qrnmz2t6SdYdJPqZMbh54SVumYEoh65NUmdk9hbBqt2TUVxVui fh4QfmqrPq27ujqF9MaRWKW4= Received: from zn.tnic (p5de8e020.dip0.t-ipconnect.de [93.232.224.32]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with UTF8SMTPSA id BF9C040E0163; Mon, 23 Mar 2026 12:17:16 +0000 (UTC) Date: Mon, 23 Mar 2026 13:17:08 +0100 From: Borislav Petkov To: Paolo Bonzini Cc: "Kernel Mailing List, Linux" , kvm , Jon Kohler , Marcelo Tosatti , Nikunj A Dadhania , Amit Shah , Sean Christopherson Subject: Re: [PATCH 18/22] KVM: SVM: add GMET bit definitions Message-ID: <20260323121708.GAacEvRNp0sFRf8dA-@fat_crate.local> References: <20260321000931.1947084-1-pbonzini@redhat.com> <20260321000931.1947084-19-pbonzini@redhat.com> <20260321115826.GCab6H4lNYIih_g0B0@fat_crate.local> <20260321154219.GEab68W-ln67dqTB5x@fat_crate.local> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Mon, Mar 23, 2026 at 08:53:32AM +0100, Paolo Bonzini wrote: > I am not sure what you mean by ABI in this context, maybe "there are It means that once we show it in /proc/cpuinfo, we're stuck with it forever because something in userspace might depend on it. So we try to avoid that if it can be solved in a different way. > rules for whether to add stuff to cpuinfo.rst"? If so, GMET matches > what cpuinfo.rst says: > > * the kernel knows about the feature enough to have an X86_FEATURE bit > * the kernel supports it and is currently making it available to userspace > * the hardware supports it. > > The bullet that applies here is the second from the above list: 1) > this series makes the feature available for userspace and guests to > use it, This is the key question: what in userspace is going to parse /proc/cpuinfo and look for "gmet"? Because parsing /proc/cpuinfo is the silliest option available but glibc does it and for some things like, "did the kernel *actually* enable this?" it is the only way. If the above applies, can this be solved in a different way? CPUID, guest_cpu_cap_has(), whatever... Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette