From nobody Sun May 19 05:22:50 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1644412411143787.7776363026138; Wed, 9 Feb 2022 05:13:31 -0800 (PST) Received: from list by lists.xenproject.org with outflank-mailman.269137.463139 (Exim 4.92) (envelope-from ) id 1nHmmY-0005LU-88; Wed, 09 Feb 2022 13:13:14 +0000 Received: by outflank-mailman (output) from mailman id 269137.463139; Wed, 09 Feb 2022 13:13:14 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nHmmY-0005LN-3z; Wed, 09 Feb 2022 13:13:14 +0000 Received: by outflank-mailman (input) for mailman id 269137; Wed, 09 Feb 2022 13:13:12 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nHmmV-0005LH-LQ for xen-devel@lists.xenproject.org; Wed, 09 Feb 2022 13:13:12 +0000 Received: from smtp1.irit.fr (smtp1.irit.fr [141.115.24.2]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 06be1a6b-89aa-11ec-8f75-fffcc8bd4f1a; Wed, 09 Feb 2022 14:13:09 +0100 (CET) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 06be1a6b-89aa-11ec-8f75-fffcc8bd4f1a From: Tu Dinh Ngoc To: xen-devel@lists.xenproject.org Cc: Tu Dinh Ngoc Subject: [PATCH v2] x86: Use low memory size directly from Multiboot Date: Wed, 9 Feb 2022 14:12:51 +0100 Message-Id: <20220209131251.387-1-dinhngoc.tu@irit.fr> In-Reply-To: References: Content-Transfer-Encoding: quoted-printable X-ZM-MESSAGEID: 1644412411932100001 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Previously, Xen used information from the BDA to detect the amount of available low memory. This does not work on some scenarios such as Coreboot, or when booting from Kexec on a UEFI system without CSM. Use the information directly supplied by Multiboot boot information instead. --- xen/arch/x86/boot/head.S | 34 ++++++++++++---------------------- 1 file changed, 12 insertions(+), 22 deletions(-) diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S index dd1bea0d10..62fe3fe55b 100644 --- a/xen/arch/x86/boot/head.S +++ b/xen/arch/x86/boot/head.S @@ -524,33 +524,23 @@ trampoline_bios_setup: mov %ecx,%fs mov %ecx,%gs =20 - /* Set up trampoline segment 64k below EBDA */ - movzwl 0x40e,%ecx /* EBDA segment */ - cmp $0xa000,%ecx /* sanity check (high) */ - jae 0f - cmp $0x4000,%ecx /* sanity check (low) */ - jae 1f -0: - movzwl 0x413,%ecx /* use base memory size on failure */ - shl $10-4,%ecx -1: + /* Use lower memory size directly from Multiboot */ + mov %edx,%ecx /* - * Compare the value in the BDA with the information from the - * multiboot structure (if available) and use the smallest. + * Old Kexec used to report the value in bytes instead of kilobytes + * like it's supposed to, so fix that if detected. */ - cmp $0x100,%edx /* is the multiboot value too small? */ - jb 2f /* if so, do not use it */ - shl $10-4,%edx - cmp %ecx,%edx /* compare with BDA value */ - cmovb %edx,%ecx /* and use the smaller */ + cmpl $640,%ecx + jbe 1f + shr $10,%ecx +1: + /* From arch/x86/smpboot.c: start_eip had better be page-aligned! = */ + shr $2,%ecx =20 -2: /* Reserve memory for the trampoline and the low-memory stack. */ - sub $((TRAMPOLINE_SPACE+TRAMPOLINE_STACK_SPACE)>>4),%ecx + sub $((TRAMPOLINE_SPACE+TRAMPOLINE_STACK_SPACE)>>12),%ecx =20 - /* From arch/x86/smpboot.c: start_eip had better be page-aligned! = */ - xor %cl, %cl - shl $4, %ecx + shl $12,%ecx mov %ecx,sym_esi(trampoline_phys) =20 trampoline_setup: --=20 2.25.1