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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 871B1C4708A for ; Thu, 27 May 2021 11:49:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E13C613B4 for ; Thu, 27 May 2021 11:49:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233270AbhE0Luq (ORCPT ); Thu, 27 May 2021 07:50:46 -0400 Received: from mail.skyhub.de ([5.9.137.197]:54910 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233633AbhE0Lup (ORCPT ); Thu, 27 May 2021 07:50:45 -0400 Received: from zn.tnic (p200300ec2f0f02008ae29220a5f6f448.dip0.t-ipconnect.de [IPv6:2003:ec:2f0f:200:8ae2:9220:a5f6:f448]) (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 C06C21EC01DF; Thu, 27 May 2021 13:49:11 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1622116151; 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=4hf7uF3C3I8f6GPjngHoeAScPG99btQaF7u7u7H1D/A=; b=Sgaak1NAhP9i6jE1h6KeI0CFwvsb66ueQKL0EFfIisNKKFKCoTW1tpdbkI7bXxWcuy/MCK 80H09PtaLz2sMTfzm5E9z7fMJcu+d/OVcF8V0Bywzlm2RLd5hoiasH2O0YGO4vm7DOsPPZ I7YCb5bhulGA5S2gyslVXUGbksoe9/Y= Date: Thu, 27 May 2021 13:49:05 +0200 From: Borislav Petkov To: Brijesh Singh Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, tglx@linutronix.de, jroedel@suse.de, thomas.lendacky@amd.com, pbonzini@redhat.com, mingo@redhat.com, dave.hansen@intel.com, rientjes@google.com, seanjc@google.com, peterz@infradead.org, hpa@zytor.com, tony.luck@intel.com Subject: Re: [PATCH Part1 RFC v2 16/20] x86/kernel: Validate rom memory before accessing when SEV-SNP is active Message-ID: References: <20210430121616.2295-1-brijesh.singh@amd.com> <20210430121616.2295-17-brijesh.singh@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210430121616.2295-17-brijesh.singh@amd.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Apr 30, 2021 at 07:16:12AM -0500, Brijesh Singh wrote: > + /* > + * The ROM memory is not part of the E820 system RAM and is not pre-validated > + * by the BIOS. The kernel page table maps the ROM region as encrypted memory, > + * the SEV-SNP requires the encrypted memory must be validated before the > + * access. Validate the ROM before accessing it. > + */ > + n = ((system_rom_resource.end + 1) - video_rom_resource.start) >> PAGE_SHIFT; > + early_snp_set_memory_private((unsigned long)__va(video_rom_resource.start), > + video_rom_resource.start, n); >From last review: I don't like this sprinkling of SNP-special stuff that needs to be done, around the tree. Instead, pls define a function called snp_prep_memory(unsigned long pa, unsigned int num_pages, enum operation); or so which does all the manipulation needed and the callsites only simply unconditionally call that function so that all detail is extracted and optimized away when not config-enabled. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette