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[2604:1380:40f1:3f00::1]) by mx.google.com with ESMTPS id s22-20020a170902a51600b001dc3437ccabsi1453716plq.580.2024.02.27.07.34.51 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Feb 2024 07:34:51 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-83456-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=UUs9dr7x; arc=pass (i=1 dkim=pass dkdomain=kernel.org); spf=pass (google.com: domain of linux-kernel+bounces-83456-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-83456-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sy.mirrors.kernel.org (Postfix) with ESMTPS id E036DB21909 for ; Tue, 27 Feb 2024 15:02:04 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9D298149DF2; Tue, 27 Feb 2024 14:57:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UUs9dr7x" Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C7352149DED for ; Tue, 27 Feb 2024 14:57:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709045875; cv=none; b=tlk9s3XglzEn51C0ikyR03eZF3ikqA08rwHbKgYKrQnRhDp2YpMJhUlcv5T0/eI6yFynph+RgxQ1LEFa7IkAv19AsCErAWwfqY2AUz1h0H9oSmXHcD7lSCy8PjN6TL3IEa7GmXXl8TtYsPT4bsjZV6bmgqQ/D0UTfHzFeV4O5MY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709045875; c=relaxed/simple; bh=ZiS0Y8N/JNHPCRbZw5+rrcFF3RECZft2ksh+TkOABqw=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=Qu2jYg2KM3+NtiqVOqI3QuLSN+Zdqrhl8butTkAgsLXQNdVlmGFzXNYmU+lkE74df3s3VQROsrjJOWECPdua+7l61WMj8YO2pjKGAl+Il0ipmX8QODJD3DQxVZQ8jw/Tqly3B6vEie/s/OMALIXQecaamN2RGrudqYQ9BhOVkFs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UUs9dr7x; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61B60C433F1 for ; Tue, 27 Feb 2024 14:57:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709045875; bh=ZiS0Y8N/JNHPCRbZw5+rrcFF3RECZft2ksh+TkOABqw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=UUs9dr7x5w4S2+mheN0Uu/lGmDjtCEatSMfcKIYJMY7q3NtxfskvrvnzuviFWkxBc 8yTOGeZ/AmMBjhvNLSZsGcFcC+VaMTSJ/7P4qidUBIOymRdvngM5HJ2NLFg+Sqv9/8 0JbmSDJ7ET5LIYXTRExJh2ZJwnjA+gkgQSDRkxtOFLY/IixIg2E0/Wsn9bgyvz9h4B tkdu2jl3+iFHPQ5MPXmP3NHXxkYYPXsc/suk/hPUYGMYROub4hBnu+aLVqlBGcqynY Fe0vrbhOpOMsY1z176OekD9vujRn7+tUjoGosn8iOn/ulIe7B1VM2hlTaL2eOyKEPJ qAZo3bSE4hH6w== Received: by mail-lf1-f45.google.com with SMTP id 2adb3069b0e04-512b29f82d1so5948880e87.1 for ; Tue, 27 Feb 2024 06:57:55 -0800 (PST) X-Gm-Message-State: AOJu0YwT2/1lnm75XRfhIZMekcnc/ZmGOhnezYfImD7kQHk4Ke0hbGHB IF/gyioVN1aWUHktK8lh1tJdjYJMde7w0UDg+vK18rJOHgSxQ1cjeoSJEDCQusS3pCqfuu5pp4h LByFny2nknlVkamGOXgP3EbuUqGg= X-Received: by 2002:ac2:4833:0:b0:512:ccd2:5cb0 with SMTP id 19-20020ac24833000000b00512ccd25cb0mr6502413lft.29.1709045873616; Tue, 27 Feb 2024 06:57:53 -0800 (PST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240226220544.70769-1-brgerst@gmail.com> In-Reply-To: <20240226220544.70769-1-brgerst@gmail.com> From: Ard Biesheuvel Date: Tue, 27 Feb 2024 15:57:42 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2] x86/boot/64: Load kernel GDT in early boot To: Brian Gerst Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Ingo Molnar , Thomas Gleixner , Borislav Petkov , "H . Peter Anvin" , Peter Zijlstra Content-Type: text/plain; charset="UTF-8" On Mon, 26 Feb 2024 at 23:05, Brian Gerst wrote: > > Instead of loading a duplicate GDT just for early boot, load the kernel > GDT from its physical address. > > Signed-off-by: Brian Gerst > --- > v2: Updated to latest tip tree > Acked-by: Ard Biesheuvel > arch/x86/include/asm/desc.h | 1 + > arch/x86/kernel/head64.c | 13 ++----------- > 2 files changed, 3 insertions(+), 11 deletions(-) > > diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h > index ec95fe44fa3a..62dc9f59ea76 100644 > --- a/arch/x86/include/asm/desc.h > +++ b/arch/x86/include/asm/desc.h > @@ -46,6 +46,7 @@ struct gdt_page { > } __attribute__((aligned(PAGE_SIZE))); > > DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page); > +DECLARE_INIT_PER_CPU(gdt_page); > > /* Provide the original GDT */ > static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu) > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index 72351c3121a6..fd77a266f29d 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -68,15 +68,6 @@ unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4; > EXPORT_SYMBOL(vmemmap_base); > #endif > > -/* > - * GDT used on the boot CPU before switching to virtual addresses. > - */ > -static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = { > - [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff), > - [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff), > - [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff), > -}; > - > #ifdef CONFIG_X86_5LEVEL > static void __head *fixup_pointer(void *ptr, unsigned long physaddr) > { > @@ -589,8 +580,8 @@ void __head startup_64_setup_gdt_idt(void) > void *handler = NULL; > > struct desc_ptr startup_gdt_descr = { > - .address = (unsigned long)&RIP_REL_REF(startup_gdt), > - .size = sizeof(startup_gdt) - 1, > + .address = (unsigned long)&RIP_REL_REF(init_per_cpu_var(gdt_page.gdt)), > + .size = GDT_SIZE - 1, > }; > > /* Load GDT */ > > base-commit: afb9cce6ad6e808cf659f43925941be96f61b9c9 > -- > 2.43.2 >