From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Lendacky Subject: Re: [RFC Part1 PATCH v3 02/17] x86/CPU/AMD: Add the Secure Encrypted Virtualization CPU feature Date: Tue, 25 Jul 2017 10:29:40 -0500 Message-ID: References: <20170724190757.11278-1-brijesh.singh@amd.com> <20170724190757.11278-3-brijesh.singh@amd.com> <20170725102657.GD21822@nazgul.tnic> <7236d267-ebcb-8b45-b8d3-5955903e395f@amd.com> <20170725143615.GA26029@nazgul.tnic> <47ccc32e-e113-48e0-d2e0-2f23b37cc452@amd.com> <20170725151301.GC26029@nazgul.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170725151301.GC26029@nazgul.tnic> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Borislav Petkov Cc: Brijesh Singh , linux-kernel@vger.kernel.org, x86@kernel.org, linux-efi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Andy Lutomirski , Tony Luck , Piotr Luc , Fenghua Yu , Lu Baolu , Reza Arbab , David Howells , Matt Fleming , "Kirill A . Shutemov" , Laura Abbott , Ard Biesheuvel , Andrew Morton , Eric List-Id: linux-efi@vger.kernel.org On 7/25/2017 10:13 AM, Borislav Petkov wrote: > On Tue, Jul 25, 2017 at 09:58:54AM -0500, Tom Lendacky wrote: >> True, but it is more about being accurate and making sure the value is >> correct where ever it may be used. > > So early_identify_cpu() initializes phys_bits to 32 on 32-bit. > Subtracting it there would actually make actively it wrong, AFAICT. But early_identify_cpu() calls get_cpu_cap() which will check for cpuid leaf 0x80000008 support and set x86_phys_bits. I'll try to build and run a 32-bit kernel and see how this all flows. Thanks, Tom >