Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751747AbbEBMRO (ORCPT ); Sat, 2 May 2015 08:17:14 -0400 Received: from vserver.eikelenboom.it ([84.200.39.61]:41007 "EHLO smtp.eikelenboom.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbbEBMRM (ORCPT ); Sat, 2 May 2015 08:17:12 -0400 X-Greylist: delayed 385 seconds by postgrey-1.27 at vger.kernel.org; Sat, 02 May 2015 08:17:12 EDT Date: Sat, 2 May 2015 14:10:40 +0200 From: Sander Eikelenboom Organization: Eikelenboom IT services X-Priority: 3 (Normal) Message-ID: <943161960.20150502141040@eikelenboom.it> To: Boris Ostrovsky CC: David Vrabel , konrad.wilk@oracle.com, , , , , , Subject: Re: [Xen-devel] [PATCH] hypervisor/x86/xen: Unset X86_BUG_SYSRET_SS_ATTRS on Xen PV guests In-Reply-To: <55435782.3040506@citrix.com> References: <1430420925-20474-1-git-send-email-boris.ostrovsky@oracle.com> <55435782.3040506@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1139 Lines: 33 Friday, May 1, 2015, 12:37:54 PM, you wrote: > On 30/04/15 20:08, Boris Ostrovsky wrote: >> Commit 61f01dd941ba ("x86_64, asm: Work around AMD SYSRET SS descriptor >> attribute issue") makes AMD processors set SS to __KERNEL_DS in >> __switch_to() to deal with cases when SS is NULL. >> >> This breaks Xen PV guests who do not want to load SS with__KERNEL_DS. >> >> Since the problem that the commit is trying to address would have to be >> fixed in the hypervisor (if it in fact exists under Xen) there is no >> reason to set X86_BUG_SYSRET_SS_ATTRS flag for PV VPCUs here. >> >> This can be easily achieved by adding x86_hyper_xen_hvm.set_cpu_features >> op which will clear this flag. (And since this structure is no longer >> HVM-specific we should do some renaming). > Applied to for-linus-4.1b, thanks. > David Also works fine here. Thanks Boris ! -- Sander -- 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/