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 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DF3CCC433F5 for ; Thu, 16 Dec 2021 11:00:48 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.247859.427428 (Exim 4.92) (envelope-from ) id 1mxoUp-0002PP-9N; Thu, 16 Dec 2021 11:00:23 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 247859.427428; Thu, 16 Dec 2021 11:00:23 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mxoUp-0002PI-5t; Thu, 16 Dec 2021 11:00:23 +0000 Received: by outflank-mailman (input) for mailman id 247859; Thu, 16 Dec 2021 11:00:21 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mxoUn-0002PC-JQ for xen-devel@lists.xenproject.org; Thu, 16 Dec 2021 11:00:21 +0000 Received: from ppsw-33.csi.cam.ac.uk (ppsw-33.csi.cam.ac.uk [131.111.8.133]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 5b12132c-5e5f-11ec-9e60-abaf8a552007; Thu, 16 Dec 2021 12:00:19 +0100 (CET) Received: from hades.srcf.societies.cam.ac.uk ([131.111.179.67]:43862) by ppsw-33.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.137]:25) with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) id 1mxoUk-000aVM-gZ (Exim 4.95) (return-path ); Thu, 16 Dec 2021 11:00:18 +0000 Received: from [192.168.1.10] (host-92-12-61-86.as13285.net [92.12.61.86]) (Authenticated sender: amc96) by hades.srcf.societies.cam.ac.uk (Postfix) with ESMTPSA id 01E271FA47; Thu, 16 Dec 2021 11:00:17 +0000 (GMT) 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: 5b12132c-5e5f-11ec-9e60-abaf8a552007 X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: https://help.uis.cam.ac.uk/email-scanner-virus Message-ID: Date: Thu, 16 Dec 2021 11:00:17 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH] revert "hvmloader: PA range 0xfc000000-0xffffffff should be UC" Content-Language: en-GB To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Jan Beulich Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper , Wei Liu References: <036c6899-dbfe-eca8-7974-5a13d20455a7@suse.com> From: Andrew Cooper In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 16/12/2021 09:54, Roger Pau Monné wrote: > On Tue, Dec 14, 2021 at 09:21:22AM +0100, Jan Beulich wrote: >> This reverts commit c22bd567ce22f6ad9bd93318ad0d7fd1c2eadb0d. >> >> While its description is correct from an abstract or real hardware pov, >> the range is special inside HVM guests. The range being UC in particular >> gets in the way of OVMF, which places itself at [FFE00000,FFFFFFFF]. > I would assume this range to be unpopulated? Does hvmloader populate > it in order to place ovmf? It's generally not unpopulated.  The video RAM lives there until the VGA BAR is reprogrammed. The reason OVMF places itself there is because it is where the real SPI ROM is mapped in address space on a real system. >> While this is benign to epte_get_entry_emt() as long as the IOMMU isn't >> enabled for a guest, it becomes a very noticable problem otherwise: It >> takes about half a minute for OVMF to decompress itself into its >> designated address range. >> >> And even beyond OVMF there's no reason to have e.g. the ACPI memory >> range marked UC. >> >> Fixes: c22bd567ce22 ("hvmloader: PA range 0xfc000000-0xffffffff should be UC") >> Signed-off-by: Jan Beulich > Reviewed-by: Roger Pau Monné Acked-by: Andrew Cooper ~Andrew