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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 CA2B5C433DB for ; Mon, 25 Jan 2021 15:25:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 914C42310E for ; Mon, 25 Jan 2021 15:25:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729986AbhAYPUS (ORCPT ); Mon, 25 Jan 2021 10:20:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729844AbhAYO4u (ORCPT ); Mon, 25 Jan 2021 09:56:50 -0500 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95461C061574 for ; Mon, 25 Jan 2021 06:56:00 -0800 (PST) Received: from zn.tnic (p200300ec2f09db0095810f165069682a.dip0.t-ipconnect.de [IPv6:2003:ec:2f09:db00:9581:f16:5069:682a]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 1D88C1EC0572; Mon, 25 Jan 2021 15:55:59 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1611586559; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=Xbmme6GPysiAM30p3FHQ7t0SqIqLTadlifqkOIOeX7w=; b=XBDN0S9oHrd0cVkGGvg4dl7QfxlPampHCLYMp0YbMRGpN7h0eoPPcKB0EjnLeESghZo4JF pGgGYhLQiDzxB0l4tuX3Gb4lxhk016px6SbRptHLaJePGTfUdXvJd1xxlXUyi7nPOjHmjC PIB4AQbDuSHQ19k/8R6M9e0r88fjTT8= Date: Mon, 25 Jan 2021 15:55:58 +0100 From: Borislav Petkov To: Mike Rapoport Cc: Andrew Morton , Andrea Arcangeli , Baoquan He , David Hildenbrand , "H. Peter Anvin" , Ingo Molnar , Mel Gorman , Michal Hocko , Mike Rapoport , Qian Cai , Thomas Gleixner , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Subject: Re: [PATCH 2/2] x86/setup: merge several reservations of start of the memory Message-ID: <20210125145558.GE23070@zn.tnic> References: <20210115083255.12744-1-rppt@kernel.org> <20210115083255.12744-3-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210115083255.12744-3-rppt@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 15, 2021 at 10:32:55AM +0200, Mike Rapoport wrote: > From: Mike Rapoport > > Currently the first several pages are reserved both to avoid leaking their > contents on systems with L1TF and to avoid corrupting BIOS memory. > > Merge the two memory reservations. > > Signed-off-by: Mike Rapoport > --- > arch/x86/kernel/setup.c | 29 +++++++++++------------------ > 1 file changed, 11 insertions(+), 18 deletions(-) > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 32cd2e790a0a..3f2fd67240f8 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -715,20 +715,6 @@ static int __init parse_reservelow(char *p) > > early_param("reservelow", parse_reservelow); > > -static void __init trim_low_memory_range(void) > -{ > - /* > - * A special case is the first 4Kb of memory; > - * This is a BIOS owned area, not kernel ram, but generally > - * not listed as such in the E820 table. > - * > - * This typically reserves additional memory (64KiB by default) > - * since some BIOSes are known to corrupt low memory. See the > - * Kconfig help text for X86_RESERVE_LOW. > - */ > - memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); > -} > - > static void __init early_reserve_memory(void) > { > /* > @@ -741,10 +727,18 @@ static void __init early_reserve_memory(void) > (unsigned long)__end_of_kernel_reserve - (unsigned long)_text); > > /* > - * Make sure page 0 is always reserved because on systems with > - * L1TF its contents can be leaked to user processes. > + * The first 4Kb of memory is a BIOS owned area, but generally it is > + * not listed as such in the E820 table. > + * > + * Reserve the first memory page and typically some additional > + * memory (64KiB by default) since some BIOSes are known to corrupt > + * low memory. See the Kconfig help text for X86_RESERVE_LOW. > + * > + * In addition, we must make sure page 0 is always reserved because s/we must// Other than that: Reviewed-by: Borislav Petkov -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette