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 09:58:54 -0500 Message-ID: <47ccc32e-e113-48e0-d2e0-2f23b37cc452@amd.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170725143615.GA26029@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 9:36 AM, Borislav Petkov wrote: > On Tue, Jul 25, 2017 at 09:29:40AM -0500, Tom Lendacky wrote: >> Yup, we can do something like that. I believe the only change that >> would be needed to your patch would be to move the IS_ENABLED() check >> to after the physical address space reduction check. > > Yeah, I wasn't sure about that. The logic is that if BIOS has enabled > SME and thus reduction is in place, we need to update x86_phys_bits on > 32-bit regardless, right? > > But, come to think of it, that reduction won't have any effect since we > have 32-bit addresses and the reduction is above 32-bits, right? And > thus it is moot. True, but it is more about being accurate and making sure the value is correct where ever it may be used. Thanks, Tom > > Or? > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from NAM01-BY2-obe.outbound.protection.outlook.com (mail-by2nam01on0077.outbound.protection.outlook.com [104.47.34.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xH1bh0xLyzDqmr for ; Wed, 26 Jul 2017 00:59:11 +1000 (AEST) Subject: Re: [RFC Part1 PATCH v3 02/17] x86/CPU/AMD: Add the Secure Encrypted Virtualization CPU feature 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 Biederman , Benjamin Herrenschmidt , Paul Mackerras , Konrad Rzeszutek Wilk , Jonathan Corbet , Dave Airlie , Kees Cook , Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Arnd Bergmann , Tejun Heo , Christoph Lameter 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> From: Tom Lendacky Message-ID: <47ccc32e-e113-48e0-d2e0-2f23b37cc452@amd.com> Date: Tue, 25 Jul 2017 09:58:54 -0500 MIME-Version: 1.0 In-Reply-To: <20170725143615.GA26029@nazgul.tnic> Content-Type: text/plain; charset=utf-8; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 7/25/2017 9:36 AM, Borislav Petkov wrote: > On Tue, Jul 25, 2017 at 09:29:40AM -0500, Tom Lendacky wrote: >> Yup, we can do something like that. I believe the only change that >> would be needed to your patch would be to move the IS_ENABLED() check >> to after the physical address space reduction check. > > Yeah, I wasn't sure about that. The logic is that if BIOS has enabled > SME and thus reduction is in place, we need to update x86_phys_bits on > 32-bit regardless, right? > > But, come to think of it, that reduction won't have any effect since we > have 32-bit addresses and the reduction is above 32-bits, right? And > thus it is moot. True, but it is more about being accurate and making sure the value is correct where ever it may be used. Thanks, Tom > > Or? > 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 09:58:54 -0500 Message-ID: <47ccc32e-e113-48e0-d2e0-2f23b37cc452@amd.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit 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 Biederman To: Borislav Petkov Return-path: In-Reply-To: <20170725143615.GA26029@nazgul.tnic> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 7/25/2017 9:36 AM, Borislav Petkov wrote: > On Tue, Jul 25, 2017 at 09:29:40AM -0500, Tom Lendacky wrote: >> Yup, we can do something like that. I believe the only change that >> would be needed to your patch would be to move the IS_ENABLED() check >> to after the physical address space reduction check. > > Yeah, I wasn't sure about that. The logic is that if BIOS has enabled > SME and thus reduction is in place, we need to update x86_phys_bits on > 32-bit regardless, right? > > But, come to think of it, that reduction won't have any effect since we > have 32-bit addresses and the reduction is above 32-bits, right? And > thus it is moot. True, but it is more about being accurate and making sure the value is correct where ever it may be used. Thanks, Tom > > Or? >