From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 659746B0279 for ; Wed, 31 May 2017 09:38:00 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id p29so11287950pgn.3 for ; Wed, 31 May 2017 06:38:00 -0700 (PDT) Received: from NAM02-CY1-obe.outbound.protection.outlook.com (mail-cys01nam02on0073.outbound.protection.outlook.com. [104.47.37.73]) by mx.google.com with ESMTPS id t61si48242728plb.200.2017.05.31.06.37.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 31 May 2017 06:37:59 -0700 (PDT) Subject: Re: [PATCH v5 32/32] x86/mm: Add support to make use of Secure Memory Encryption References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net> <20170418212223.10190.85121.stgit@tlendack-t1.amdoffice.net> <20170519112703.voajtn4t7uy6nwa3@pd.tnic> <7c522f65-c5c8-9362-e1eb-d0765e3ea6c9@amd.com> <20170530145459.tyuy6veqxnrqkhgw@pd.tnic> <115ca39d-6ae7-f603-a415-ead7c4e8193d@amd.com> <20170531084923.mmlpefxfx53f3okp@pd.tnic> From: Tom Lendacky Message-ID: <706d6ae0-bc4c-5ba7-529c-b0fc5e4ad464@amd.com> Date: Wed, 31 May 2017 08:37:50 -0500 MIME-Version: 1.0 In-Reply-To: <20170531084923.mmlpefxfx53f3okp@pd.tnic> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Borislav Petkov Cc: linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Rik van Riel , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Toshimitsu Kani , Arnd Bergmann , Jonathan Corbet , Matt Fleming , "Michael S. Tsirkin" , Joerg Roedel , Konrad Rzeszutek Wilk , Paolo Bonzini , Larry Woodman , Brijesh Singh , Ingo Molnar , Andy Lutomirski , "H. Peter Anvin" , Andrey Ryabinin , Alexander Potapenko , Dave Young , Thomas Gleixner , Dmitry Vyukov On 5/31/2017 3:49 AM, Borislav Petkov wrote: > On Tue, May 30, 2017 at 10:37:03AM -0500, Tom Lendacky wrote: >> I can define the command line option and the "on" and "off" values as >> character buffers in the function and initialize them on a per character >> basis (using a static string causes the same issues as referencing a >> string constant), i.e.: >> >> char cmdline_arg[] = {'m', 'e', 'm', '_', 'e', 'n', 'c', 'r', 'y', 'p', 't', '\0'}; >> char cmdline_off[] = {'o', 'f', 'f', '\0'}; >> char cmdline_on[] = {'o', 'n', '\0'}; >> >> It doesn't look the greatest, but it works and removes the need for the >> rip-relative addressing. > > Well, I'm not thrilled about this one either. It's like being between a > rock and a hard place. :-\ > > On the one hand, we need the encryption mask before we do the fixups and > OTOH we need to do the fixups in order to access the strings properly. > Yuck. > > Well, the only thing I can think of right now is maybe define > "mem_encrypt=" at the end of head_64.S and pass it in from asm to > sme_enable() and then do the "on"/"off" comparsion with local char > buffers. That could make it less ugly... I like keeping the command line option and the values together. It may not look the greatest but I like it more than defining the command line option in head_64.S and passing it in as an argument. OTOH, I don't think the rip-relative addressing was that bad, I can always go back to that... Thanks, Tom > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org