Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754747AbbGQRxh (ORCPT ); Fri, 17 Jul 2015 13:53:37 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:50939 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754559AbbGQRxf (ORCPT ); Fri, 17 Jul 2015 13:53:35 -0400 Message-ID: <55A940CC.6090509@oracle.com> Date: Fri, 17 Jul 2015 13:52:12 -0400 From: Boris Ostrovsky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: david.vrabel@citrix.com, roger.pau@citrix.com, elena.ufimtseva@oracle.com, stefano.stabellini@eu.citrix.com, tim@xen.org, jbeulich@suse.com, andrew.cooper3@citrix.com, ian.campbell@citrix.com, ian.jackson@eu.citrix.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 4/6] xen/x86/pvh: Set up descriptors for 32-bit PVH guests References: <1437083021-24488-1-git-send-email-boris.ostrovsky@oracle.com> <1437083021-24488-5-git-send-email-boris.ostrovsky@oracle.com> <20150717152113.GB18085@l.oracle.com> <55A920FD.6050101@oracle.com> <20150717164331.GA19827@l.oracle.com> In-Reply-To: <20150717164331.GA19827@l.oracle.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2036 Lines: 47 On 07/17/2015 12:43 PM, Konrad Rzeszutek Wilk wrote: > On Fri, Jul 17, 2015 at 11:36:29AM -0400, Boris Ostrovsky wrote: >> On 07/17/2015 11:21 AM, Konrad Rzeszutek Wilk wrote: >>> On Thu, Jul 16, 2015 at 05:43:39PM -0400, Boris Ostrovsky wrote: >>>> Signed-off-by: Boris Ostrovsky >>>> --- >>>> Changes in v2: >>>> * Set segment selectors using loadsegment() instead of assembly >>>> >>>> arch/x86/xen/enlighten.c | 15 ++++++++++----- >>>> 1 file changed, 10 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c >>>> index f8dc398..d665b1d 100644 >>>> --- a/arch/x86/xen/enlighten.c >>>> +++ b/arch/x86/xen/enlighten.c >>>> @@ -1362,12 +1362,12 @@ static void __init xen_boot_params_init_edd(void) >>>> static void __ref xen_setup_gdt(int cpu) >>>> { >>>> if (xen_feature(XENFEAT_auto_translated_physmap)) { >>>> -#ifdef CONFIG_X86_64 >>>> - unsigned long dummy; >>>> + unsigned long __attribute__((unused)) dummy; >>>> - load_percpu_segment(cpu); /* We need to access per-cpu area */ >>> You removed that - where are we going to do that? As the >>> 'switch_to_new_gdt' uses the per-cpu GDT table. >> load_percpu_segment() is part of switch_to_new_gdt(), so I thought there is >> no need to call it here. >> >> But you are right --- switch_to_new_gdt() starts with get_cpu_gdt_table() >> which accesses per-CPU area. How did this manage to work then? > I was surprised as well - I was expecting your patch to have blow up. > Unless we are doing something fancy for CPU0 and for the other CPUs we > already have the per-cpu segment setup during bootup (copied from BSP)? No, %fs is zero when we enter xen_setup_gdt() (for 32-bit). In any case, I should put load_percpu_segment() back. -boris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/