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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 2BFE6C433E0 for ; Mon, 11 Jan 2021 08:50:08 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CFF0C22581 for ; Mon, 11 Jan 2021 08:50:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CFF0C22581 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.64663.114256 (Exim 4.92) (envelope-from ) id 1kysth-0006fR-BT; Mon, 11 Jan 2021 08:49:57 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 64663.114256; Mon, 11 Jan 2021 08:49:57 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kysth-0006fK-7y; Mon, 11 Jan 2021 08:49:57 +0000 Received: by outflank-mailman (input) for mailman id 64663; Mon, 11 Jan 2021 08:49:56 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kystg-0006fF-71 for xen-devel@lists.xenproject.org; Mon, 11 Jan 2021 08:49:56 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 9030a980-4e22-4d91-83fc-5e87270209c3; Mon, 11 Jan 2021 08:49:55 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8326FAD2B; Mon, 11 Jan 2021 08:49:54 +0000 (UTC) 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: 9030a980-4e22-4d91-83fc-5e87270209c3 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1610354994; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6JpEEx487B/qI2x5uPIhVpi6GWgTrJkWc5mqOtm7pw4=; b=CX+jvK9pzOJUAc7FIH/d8oFoPRUQvFUOATS6wslIX8PmZjMbL+irqklI0zZhL6G4beOeWw X8fr5ZTPInjDj2P1653SXalfgLzglgdMT5E0ic3sA7pLs269NHNukS+fzy8CkaXjvvj6Wf 9JEayxnQ61xDHiuIVoMrILqGGkQPvQQ= Subject: Re: [PATCH v2] xen/arm: do not read MVFR2 when is not defined To: Stefano Stabellini , bertrand.marquis@arm.com Cc: julien@xen.org, Volodymyr_Babchuk@epam.com, Stefano Stabellini , xen-devel@lists.xenproject.org References: <20210108192243.25889-1-sstabellini@kernel.org> From: Jan Beulich Message-ID: Date: Mon, 11 Jan 2021 09:49:53 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210108192243.25889-1-sstabellini@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 08.01.2021 20:22, Stefano Stabellini wrote: > MVFR2 is not available on ARMv7. It is available on ARMv8 aarch32 and > aarch64. If Xen reads MVFR2 on ARMv7 it could crash. > > Avoid the issue by doing the following: > > - define MVFR2_MAYBE_UNDEFINED on arm32 > - if MVFR2_MAYBE_UNDEFINED, do not attempt to read MVFR2 in Xen > - keep the 3rd register_t in struct cpuinfo_arm.mvfr on arm32 so that a > guest read to the register returns '0' instead of crashing the guest. > > '0' is an appropriate value to return to the guest because it is defined > as "no support for miscellaneous features". > > Aarch64 Xen is not affected by this patch. But it looks to also be affected by ... > Fixes: 9cfdb489af81 ("xen/arm: Add ID registers and complete cpuinfo") ... this, faulting (according to osstest logs) early during boot on 000000000025D314 mrs x1, id_pfr2_el1 afaict. Jan