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=-17.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 8A375C433E0 for ; Tue, 5 Jan 2021 19:20:29 +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 42DD622D5B for ; Tue, 5 Jan 2021 19:20:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42DD622D5B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org 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.62179.109949 (Exim 4.92) (envelope-from ) id 1kwrsT-0007uF-8y; Tue, 05 Jan 2021 19:20:21 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 62179.109949; Tue, 05 Jan 2021 19:20:21 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kwrsT-0007u8-5u; Tue, 05 Jan 2021 19:20:21 +0000 Received: by outflank-mailman (input) for mailman id 62179; Tue, 05 Jan 2021 19:20:20 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kwrsS-0007u3-Ew for xen-devel@lists.xenproject.org; Tue, 05 Jan 2021 19:20:20 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kwrsM-0008C3-Nd; Tue, 05 Jan 2021 19:20:14 +0000 Received: from [54.239.6.177] (helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1kwrsM-00061g-F2; Tue, 05 Jan 2021 19:20:14 +0000 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" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=n+9VYMUuCUAFtRFpil3X268193X7jEHCqwXEN4OxvWI=; b=02X7pXgsSQJgW2i+E2XBFdPZJ1 EYXM/aLHOsKja5pIOeIMXFeLwm4EAFjB7raY3LsSaYlG/2pqqWP0cpkh1zhAoPwzvW0pm/ir7Vxj+ crtsrmjkZk3j7FnkM6x/GSsms5d/Cs3dnzDYtd+JHHEXOdSv8vpVpn3Is+dq1C6N8Q0E=; Subject: Re: [PATCH] xen/arm: do not read MVFR2 on arm32 To: Stefano Stabellini , xen-devel@lists.xenproject.org Cc: bertrand.marquis@arm.com, iwj@xenproject.org, Andrew.Cooper3@citrix.com, Volodymyr_Babchuk@epam.com, Stefano Stabellini References: <20210105190548.13677-1-sstabellini@kernel.org> From: Julien Grall Message-ID: <2646e16b-e59e-3f94-5d3e-59c8b8dab857@xen.org> Date: Tue, 5 Jan 2021 19:20:12 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210105190548.13677-1-sstabellini@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit On 05/01/2021 19:05, Stefano Stabellini wrote: > MVFR2 is not available on arm32. Don't try to read it. Make MVFR2 arm64 > only. Not really, MVFR2 is allocated when running in AArch32 mode on Armv8. It just doesn't exist on Armv7. See my answer your previous e-mail for more details. > > Fixes: 9cfdb489af81 ("xen/arm: Add ID registers and complete cpuinfo") > Signed-off-by: Stefano Stabellini > --- > xen/arch/arm/cpufeature.c | 2 ++ > xen/include/asm-arm/cpufeature.h | 2 +- > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/cpufeature.c b/xen/arch/arm/cpufeature.c > index 1f6a85aafe..9e3377eae3 100644 > --- a/xen/arch/arm/cpufeature.c > +++ b/xen/arch/arm/cpufeature.c > @@ -150,7 +150,9 @@ void identify_cpu(struct cpuinfo_arm *c) > > c->mvfr.bits[0] = READ_SYSREG(MVFR0_EL1); > c->mvfr.bits[1] = READ_SYSREG(MVFR1_EL1); > +#ifdef CONFIG_ARM_64 > c->mvfr.bits[2] = READ_SYSREG(MVFR2_EL1); > +#endif > } > > /* > diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h > index 6058744c18..fa20cb493a 100644 > --- a/xen/include/asm-arm/cpufeature.h > +++ b/xen/include/asm-arm/cpufeature.h > @@ -272,7 +272,7 @@ struct cpuinfo_arm { > } isa32; > > struct { > - register_t bits[3]; > + register_t bits[2 + IS_ENABLED(CONFIG_ARM_64)]; mvfr.bits[2] will be accessed from arch/arm/vcpreg.c, so you will provide garbagge to guest if the user happen to run Xen on Arm32 on Armv8. Given that MVFR2 exists, I think it would be best to keep the definition in cpuinfo_arm around and only hardcode the value in cpufeature.c. Please see my previous e-mail for more rationale on this approach. Cheers, -- Julien Grall