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=-12.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 AB9A3C433B4 for ; Fri, 21 May 2021 07:26:25 +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 6E84F61175 for ; Fri, 21 May 2021 07:26:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6E84F61175 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.131165.245291 (Exim 4.92) (envelope-from ) id 1ljzXv-0001Y8-QB; Fri, 21 May 2021 07:26:11 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 131165.245291; Fri, 21 May 2021 07:26:11 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ljzXv-0001Y1-MI; Fri, 21 May 2021 07:26:11 +0000 Received: by outflank-mailman (input) for mailman id 131165; Fri, 21 May 2021 07:26:10 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ljzXu-0001Xv-Fq for xen-devel@lists.xenproject.org; Fri, 21 May 2021 07:26:10 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id f31b127d-d8d8-43de-bf31-c4e7d1435439; Fri, 21 May 2021 07:26:09 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D1B53AB64; Fri, 21 May 2021 07:26:08 +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: f31b127d-d8d8-43de-bf31-c4e7d1435439 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=1621581968; 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=QgWvsxiemLxZi6Uo1RdnfIDagmZQ6WxkASMEMiRYIuw=; b=ApjhcA9Onsc9oxlCzlv1VwnpqrBBAlRvnZAy4KReIEJDcHvIuwESNFDFJRelvJaQpoin/f lBUmfBRQ4nqTEmqzBPd2mcrIfhfnTIIkrqqBffYNhkB7XzxywFBKOWKscjsUuF7Y0ZViHO xmwqgFAU9P1ZKwQ40yVFoshHwtMTF8A= Subject: Re: [PATCH] x86/Xen: swap NX determination and GDT setup on BSP To: Juergen Gross Cc: "xen-devel@lists.xenproject.org" , Boris Ostrovsky References: <12a866b0-9e89-59f7-ebeb-a2a6cec0987a@suse.com> <65bbc317-893e-da41-97e0-c8f2e1feb3e2@suse.com> <3953076f-c2fa-2e2a-4b07-fb610046a27d@suse.com> From: Jan Beulich Message-ID: <89c46d1a-9474-0f17-3fda-4809a14adb45@suse.com> Date: Fri, 21 May 2021 09:26:08 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <3953076f-c2fa-2e2a-4b07-fb610046a27d@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 21.05.2021 09:18, Juergen Gross wrote: > On 20.05.21 14:08, Jan Beulich wrote: >> On 20.05.2021 13:57, Juergen Gross wrote: >>> On 20.05.21 13:42, Jan Beulich wrote: >>>> xen_setup_gdt(), via xen_load_gdt_boot(), wants to adjust page tables. >>>> For this to work when NX is not available, x86_configure_nx() needs to >>>> be called first. >>>> >>>> Reported-by: Olaf Hering >>>> Signed-off-by: Jan Beulich >>> >>> Reviewed-by: Juergen Gross >> >> Thanks. I guess I forgot >> >> Cc: stable@vger.kernel.org >> >> If you agree, can you please add this before pushing to Linus? > > Uh, just had a look why x86_configure_nx() was called after > xen_setup_gdt(). > > Upstream your patch will be fine, but before kernel 5.9 it will > break running as 32-bit PV guest (see commit 36104cb9012a82e7). Oh, indeed. That commit then actually introduced the issue here, and hence a Fixes: tag may be warranted. > So I will take your patch as is, but for kernels 5.8 and older I > recommend a different approach by directly setting the NX > capability after checking the cpuid bit instead of letting that > do get_cpu_cap(). Right - perhaps the only halfway viable option. 64-bit kernels predating 4f277295e54c may then also need that one, but perhaps all stable ones already have it because it was tagged for stable. Jan