From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail02.groups.io (mail02.groups.io [66.175.222.108]) by spool.mail.gandi.net (Postfix) with ESMTPS id A5AF5AC1440 for ; Thu, 11 Jan 2024 10:21:21 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=K+6e0uEywjVbkgh0hNCBlF+UU9ddxmTKC1v4XhbjRtQ=; c=relaxed/simple; d=groups.io; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version:In-Reply-To:Precedence:List-Subscribe:List-Help:Sender:List-Id:Mailing-List:Delivered-To:Reply-To:List-Unsubscribe-Post:List-Unsubscribe:Content-Type:Content-Disposition; s=20140610; t=1704968480; v=1; b=E2gk/R6e2hIkxRaX24hWI+/o6ou+TKTX7cFP0m4qMWDsaMhlV7om+ADqLC0Pa/reqZJN7TkL 2Ped9z7hgFFBts7HmxkuWpdvgJCdiM+XDqNoZwLz/zYRBVOK2XeKI4/6tpIVNZlhkXAHFLeVtPF qP50zDwp6XvcH7FAZ9U+AG2c= X-Received: by 127.0.0.2 with SMTP id 9n7jYY7687511x8QWcd5SLJz; Thu, 11 Jan 2024 02:21:20 -0800 X-Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mx.groups.io with SMTP id smtpd.web11.8625.1704968479721051404 for ; Thu, 11 Jan 2024 02:21:19 -0800 X-Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-467-DcwtM7LtMMyKwCKDNYEuvQ-1; Thu, 11 Jan 2024 05:21:15 -0500 X-MC-Unique: DcwtM7LtMMyKwCKDNYEuvQ-1 X-Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1E6A41C106AB; Thu, 11 Jan 2024 10:21:15 +0000 (UTC) X-Received: from sirius.home.kraxel.org (unknown [10.39.192.101]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DCB8B40C6EB9; Thu, 11 Jan 2024 10:21:14 +0000 (UTC) X-Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id CCE661800605; Thu, 11 Jan 2024 11:21:13 +0100 (CET) Date: Thu, 11 Jan 2024 11:21:13 +0100 From: "Gerd Hoffmann" To: Dun Tan Cc: devel@edk2.groups.io, Ray Ni , Laszlo Ersek , Rahul Kumar Subject: Re: [edk2-devel] [Patch V3] UefiCpuPkg:Limit PhysicalAddressBits in special case Message-ID: References: <20240111085947.1105-1-dun.tan@intel.com> MIME-Version: 1.0 In-Reply-To: <20240111085947.1105-1-dun.tan@intel.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Precedence: Bulk List-Subscribe: List-Help: Sender: devel@edk2.groups.io List-Id: Mailing-List: list devel@edk2.groups.io; contact devel+owner@edk2.groups.io Reply-To: devel@edk2.groups.io,kraxel@redhat.com List-Unsubscribe-Post: List-Unsubscribe=One-Click List-Unsubscribe: X-Gm-Message-State: iFmVyeZju6L4YLyLlnXvs0LCx7686176AA= Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-GND-Status: LEGIT Authentication-Results: spool.mail.gandi.net; dkim=pass header.d=groups.io header.s=20140610 header.b="E2gk/R6e"; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=redhat.com (policy=none); spf=pass (spool.mail.gandi.net: domain of bounce@groups.io designates 66.175.222.108 as permitted sender) smtp.mailfrom=bounce@groups.io On Thu, Jan 11, 2024 at 04:59:47PM +0800, Dun Tan wrote: > When creating smm page table, limit maximum > supported physical address bits returned by > CalculateMaximumSupportAddress() to 47 if > 5-Level Paging is disabled. > When 5-Level Paging is disabled and the > PhysicalAddressBits retrived from CPU HOB or > CpuId is bigger than 47, and since virtual > addresses are sign-extended, only [0, 2^47-1] > range in 52-bit physical address is mapped > in page table. > + // > + // Only [0, 2^47 -1] in 52-bit physical addresses is mapped in page table > + // when 5-Level Paging is disabled. > + // > + ASSERT (PhysicalAddressBits <= 52); > + if (!Is5LevelPagingNeeded && (PhysicalAddressBits > 47)) { > + PhysicalAddressBits = 47; > + } The code change is fine but the comment should be more verbose and explain the why 47 not 48 is used here. The discussion on the patch clearly showed that the technical background is not obvious ... take care, Gerd -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#113613): https://edk2.groups.io/g/devel/message/113613 Mute This Topic: https://groups.io/mt/103658816/7686176 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io] -=-=-=-=-=-=-=-=-=-=-=-