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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CB0FC43334 for ; Thu, 6 Sep 2018 18:48:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E48D20659 for ; Thu, 6 Sep 2018 18:48:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2E48D20659 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730526AbeIFXYp (ORCPT ); Thu, 6 Sep 2018 19:24:45 -0400 Received: from mga05.intel.com ([192.55.52.43]:61319 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727126AbeIFXYp (ORCPT ); Thu, 6 Sep 2018 19:24:45 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Sep 2018 11:47:59 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,339,1531810800"; d="scan'208";a="261333616" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.20]) by fmsmga006.fm.intel.com with ESMTP; 06 Sep 2018 11:47:50 -0700 Date: Thu, 6 Sep 2018 11:47:50 -0700 From: Sean Christopherson To: Brijesh Singh Cc: Borislav Petkov , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Tom Lendacky , Thomas Gleixner , "H. Peter Anvin" , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH v5 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active Message-ID: <20180906184750.GB4570@linux.intel.com> References: <1536234182-2809-1-git-send-email-brijesh.singh@amd.com> <1536234182-2809-6-git-send-email-brijesh.singh@amd.com> <20180906122423.GA11144@zn.tnic> <20180906135041.GB32336@linux.intel.com> <20180906141825.GB370@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 06, 2018 at 01:37:50PM -0500, Brijesh Singh wrote: > > > On 09/06/2018 09:18 AM, Sean Christopherson wrote: > .... > > >>> > >>>So are we going to be defining a decrypted section for every piece of > >>>machinery now? > >>> > >>>That's a bit too much in my book. > >>> > >>>Why can't you simply free everything in .data..decrypted on !SVE guests? > >> > >>That would prevent adding __decrypted to existing declarations, e.g. > >>hv_clock_boot, which would be ugly in its own right. A more generic > >>solution would be to add something like __decrypted_exclusive to mark > >>data that is used if and only if SEV is active, and then free the > >>SEV-only data when SEV is disabled. > > > >Oh, and we'd need to make sure __decrypted_exclusive is freed when > >!CONFIG_AMD_MEM_ENCRYPT, and preferably !sev_active() since the big > >array is used only if SEV is active. This patch unconditionally > >defines hv_clock_dec but only frees it if CONFIG_AMD_MEM_ENCRYPT=y && > >!mem_encrypt_active(). > > > > Again we have to consider the bare metal scenario while doing this. The > aux array you proposed will be added in decrypted section only when > CONFIG_AMD_MEM_ENCRYPT=y. If CONFIG_AMD_MEM_ENCRYPT=n then nothng > gets put in .data.decrypted section. At the runtime, if memory > encryption is active then .data.decrypted_hvclock will contains useful > data. > > The __decrypted attribute in "" when CONFIG_AMD_MEM_ENCRYPT=n. Right, but won't the data get dumped into the regular .bss in that case, i.e. needs to be freed?