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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 A6B36C433E0 for ; Fri, 3 Jul 2020 05:15:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81BED20772 for ; Fri, 3 Jul 2020 05:15:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726245AbgGCFPb (ORCPT ); Fri, 3 Jul 2020 01:15:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:57886 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725779AbgGCFPb (ORCPT ); Fri, 3 Jul 2020 01:15:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 33B3FB03E; Fri, 3 Jul 2020 05:15:29 +0000 (UTC) Subject: Re: [PATCH v2 1/4] x86/xen: remove 32-bit Xen PV guest support To: Boris Ostrovsky , xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org Cc: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Stefano Stabellini References: <20200701110650.16172-1-jgross@suse.com> <20200701110650.16172-2-jgross@suse.com> <6d0b517a-6c53-61d3-117b-40e33e013037@oracle.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <96159aed-9fdb-9fcb-a1b1-7c6c2c47e6a1@suse.com> Date: Fri, 3 Jul 2020 07:15:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <6d0b517a-6c53-61d3-117b-40e33e013037@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03.07.20 00:59, Boris Ostrovsky wrote: > On 7/1/20 7:06 AM, Juergen Gross wrote: >> Xen is requiring 64-bit machines today and since Xen 4.14 it can be >> built without 32-bit PV guest support. There is no need to carry the >> burden of 32-bit PV guest support in the kernel any longer, as new >> guests can be either HVM or PVH, or they can use a 64 bit kernel. >> >> Remove the 32-bit Xen PV support from the kernel. >> >> Signed-off-by: Juergen Gross >> --- >> arch/x86/entry/entry_32.S | 109 +---------- >> arch/x86/include/asm/proto.h | 2 +- >> arch/x86/include/asm/segment.h | 2 +- >> arch/x86/kernel/head_32.S | 31 --- >> arch/x86/xen/Kconfig | 3 +- >> arch/x86/xen/Makefile | 3 +- >> arch/x86/xen/apic.c | 17 -- >> arch/x86/xen/enlighten_pv.c | 48 +---- > > > Should we drop PageHighMem() test in set_aliased_prot()? > > > (And there are few other places where is is used, in mmu_pv.c) Yes, will drop those. > > > >> @@ -555,13 +547,8 @@ static void xen_load_tls(struct thread_struct *t, unsigned int cpu) >> * exception between the new %fs descriptor being loaded and >> * %fs being effectively cleared at __switch_to(). >> */ >> - if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) { >> -#ifdef CONFIG_X86_32 >> - lazy_load_gs(0); >> -#else > > > I think this also needs an adjustment to the preceding comment. Yes. > > >> >> -#ifdef CONFIG_X86_PAE >> -static void xen_set_pte_atomic(pte_t *ptep, pte_t pte) >> -{ >> - trace_xen_mmu_set_pte_atomic(ptep, pte); >> - __xen_set_pte(ptep, pte); > > > Probably not for this series but I wonder whether __xen_set_pte() should > continue to use hypercall now that we are 64-bit only. As Andrew wrote already the hypercall will be cheaper. I'll adjust the comment, though. > > >> @@ -654,14 +621,12 @@ static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd, > > > Comment above should be updated. Yes. Juergen