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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 89B15C48BD6 for ; Wed, 26 Jun 2019 09:03:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6AA2020645 for ; Wed, 26 Jun 2019 09:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726948AbfFZJD3 (ORCPT ); Wed, 26 Jun 2019 05:03:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:40168 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725379AbfFZJD2 (ORCPT ); Wed, 26 Jun 2019 05:03:28 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 80357AD09; Wed, 26 Jun 2019 09:03:26 +0000 (UTC) Subject: Re: [PATCH v2 5/7] x86/xen: nopv parameter support for HVM guest To: Zhenzhong Duan , linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@kernel.org, bp@alien8.de, hpa@zytor.com, boris.ostrovsky@oracle.com, sstabellini@kernel.org, peterz@infradead.org, srinivas.eeda@oracle.com, Ingo Molnar , xen-devel@lists.xenproject.org References: <1561377779-28036-1-git-send-email-zhenzhong.duan@oracle.com> <1561377779-28036-6-git-send-email-zhenzhong.duan@oracle.com> <99a28880-c2bf-e328-ee52-afc782af3b74@suse.com> From: Juergen Gross Message-ID: Date: Wed, 26 Jun 2019 11:03:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26.06.19 10:56, Zhenzhong Duan wrote: > > On 2019/6/25 20:31, Juergen Gross wrote: >> On 24.06.19 14:02, Zhenzhong Duan wrote: >>> PVH guest needs PV extentions to work, so nopv parameter is ignored >>> for PVH but not for HVM guest. >>> >>> In order for nopv parameter to take effect for HVM guest, we need to >>> distinguish between PVH and HVM guest early in hypervisor detection >>> code. By moving the detection of PVH in xen_platform_hvm(), >>> xen_pvh_domain() could be used for that purpose. >>> >>> Signed-off-by: Zhenzhong Duan >>> Cc: Boris Ostrovsky >>> Cc: Juergen Gross >>> Cc: Stefano Stabellini >>> Cc: Thomas Gleixner >>> Cc: Ingo Molnar >>> Cc: Borislav Petkov >>> Cc: xen-devel@lists.xenproject.org >>> --- >>>   arch/x86/xen/enlighten_hvm.c | 18 ++++++++++++------ >>>   1 file changed, 12 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c >>> index 7fcb4ea..26939e7 100644 >>> --- a/arch/x86/xen/enlighten_hvm.c >>> +++ b/arch/x86/xen/enlighten_hvm.c >>> @@ -25,6 +25,7 @@ >>>   #include "mmu.h" >>>   #include "smp.h" >>>   +extern bool nopv; >>>   static unsigned long shared_info_pfn; >>>     void xen_hvm_init_shared_info(void) >>> @@ -226,20 +227,24 @@ static uint32_t __init xen_platform_hvm(void) >>>       if (xen_pv_domain()) >>>           return 0; >>>   +#ifdef CONFIG_XEN_PVH >>> +    /* Test for PVH domain (PVH boot path taken overrides ACPI >>> flags). */ >>> +    if (!x86_platform.legacy.rtc && x86_platform.legacy.no_vga) >>> +        xen_pvh = true; >> >> Sorry, this won't work, as ACPI tables are scanned only some time later. > Hmm, right. Thanks for point out. >> >> You can test for xen_pvh being true here (for the case where the guest >> has been booted via the Xen-PVH boot entry) and handle that case, but >> the case of a PVH guest started via the normal boot entry (like via >> grub2) and nopv specified is difficult. The only idea I have right now >> would be to use another struct hypervisor_x86 for that case which will >> only be used for Xen HVM/PVH _and_ nopv specified. It should be a copy >> of the bare metal variant, but a special guest_late_init member issuing >> a big fat warning in case PVH is being detected. > > After that warning, I guess PVH will run into hang finally? If it's > true, BUG() is better? > > Adding another hypervisor_x86 is a bit redundant, I think of below change. > > I'll test it tomorrow. But appreciate your suggestion whether it's > feasible. Thanks Yes, this seems to be a viable option. > > --- a/arch/x86/xen/enlighten_hvm.c > +++ b/arch/x86/xen/enlighten_hvm.c > @@ -25,6 +25,7 @@ >  #include "mmu.h" >  #include "smp.h" > > +extern bool nopv; >  static unsigned long shared_info_pfn; > >  void xen_hvm_init_shared_info(void) > @@ -221,11 +222,37 @@ bool __init xen_hvm_need_lapic(void) >         return true; >  } > > +static __init void xen_hvm_nopv_guest_late_init(void) > +{ > +#ifdef CONFIG_XEN_PVH > +       if (x86_platform.legacy.rtc || !x86_platform.legacy.no_vga) > +               return; > + > +       /* PVH detected. */ > +       xen_pvh = true; > + > +       printk(KERN_CRIT "nopv parameter isn't supported in PVH guest\n"); > +       BUG(); > +#endif > +} > + > + >  static uint32_t __init xen_platform_hvm(void) >  { >         if (xen_pv_domain()) >                 return 0; > > +       if (xen_pvh_domain() && nopv) > +       { > +       /* guest booting via the Xen-PVH boot entry goes here */ Mind adjusting indentation of that comment? > +               printk(KERN_INFO "nopv parameter is ignored in PVH > guest\n"); > +       } > +       else if (nopv) > +       { > +       /* guest booting via normal boot entry (like via grub2) goes > here */ Same again? With those corrected and no other changes you can add my: Reviewed-by: Juergen Gross Juergen