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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B2E3CC35242 for ; Tue, 11 Feb 2020 22:29:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85E2C20708 for ; Tue, 11 Feb 2020 22:29:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581460179; bh=KbBBWvLVK/nodTeKKBzWdDxesPO9rH86mdssi2OYvmE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=Dbk3DrFcCoA6Iqe53CptNdHGBatWqb/dOxsQoJj+fk1h1LP3Fqw2eEH71s7OGrgMl 5wOibAorVGoL1sIb7gRXf7uo4jvW+lby5Dd1h22BjhjxoXiVNkTsWqs3ApRGvVYb4M BFDp4cNY8drnR4tUceibD4izmzf3DUXYJBMSfxbM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727620AbgBKW3i (ORCPT ); Tue, 11 Feb 2020 17:29:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:56158 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727029AbgBKW3i (ORCPT ); Tue, 11 Feb 2020 17:29:38 -0500 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CAFF220708 for ; Tue, 11 Feb 2020 22:29:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581460178; bh=KbBBWvLVK/nodTeKKBzWdDxesPO9rH86mdssi2OYvmE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=DEpqbkvuTZXMkr63GM08gp5bKr12sFU+qQi9r5Zj4HWdj7aslzu8jgZSigrAe2eQU RP6IiPQqnLnmgJBtQ8Sp0A5ySeD+z0EsIWHL/OXdxBcq/7M90Bi/UlGbpzm/2hPm0y UnqVtWL9dY39uCU4ZBjxv6N+E6hI3lWhITd4TEe8= Received: by mail-wm1-f51.google.com with SMTP id s144so3254827wme.1 for ; Tue, 11 Feb 2020 14:29:37 -0800 (PST) X-Gm-Message-State: APjAAAV/qP0wXGlXtZpbCGVbDMjAS+HOgtQm17JSwk1FWeiJI4WOolKn NLREegpRRNXz8l0ZURqaUbv7A64RzWRCLhso9aFiSg== X-Google-Smtp-Source: APXvYqxAXjknmXNrLHvDElSilQoVMSXHJMtigVdOl5IHhqhN4u1qCSPsaq5HYAeGjLH+qh9AEhijdGGotRqPNvYIFyc= X-Received: by 2002:a05:600c:2207:: with SMTP id z7mr8217365wml.138.1581460176281; Tue, 11 Feb 2020 14:29:36 -0800 (PST) MIME-Version: 1.0 References: <20200211135256.24617-1-joro@8bytes.org> <20200211135256.24617-26-joro@8bytes.org> In-Reply-To: <20200211135256.24617-26-joro@8bytes.org> From: Andy Lutomirski Date: Tue, 11 Feb 2020 14:29:24 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 25/62] x86/head/64: Install boot GDT To: Joerg Roedel Cc: X86 ML , "H. Peter Anvin" , Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , LKML , kvm list , Linux Virtualization , Joerg Roedel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 11, 2020 at 5:53 AM Joerg Roedel wrote: > > From: Joerg Roedel > > Handling exceptions during boot requires a working GDT. The kernel GDT > is not yet ready for use, so install a temporary boot GDT. > > Signed-off-by: Joerg Roedel > --- > arch/x86/kernel/head_64.S | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > index 4bbc770af632..5a3cde971cb7 100644 > --- a/arch/x86/kernel/head_64.S > +++ b/arch/x86/kernel/head_64.S > @@ -72,6 +72,20 @@ SYM_CODE_START_NOALIGN(startup_64) > /* Set up the stack for verify_cpu(), similar to initial_stack below */ > leaq (__end_init_task - SIZEOF_PTREGS)(%rip), %rsp > > + /* Setup boot GDT descriptor and load boot GDT */ > + leaq boot_gdt(%rip), %rax > + movq %rax, boot_gdt_base(%rip) > + lgdt boot_gdt_descr(%rip) > + > + /* GDT loaded - switch to __KERNEL_CS so IRET works reliably */ > + pushq $__KERNEL_CS > + leaq .Lon_kernel_cs(%rip), %rax > + pushq %rax > + lretq > + > +.Lon_kernel_cs: > + UNWIND_HINT_EMPTY I would suggest fixing at least SS as well.