From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932571AbdJ0ULw (ORCPT ); Fri, 27 Oct 2017 16:11:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:56144 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932470AbdJ0ULu (ORCPT ); Fri, 27 Oct 2017 16:11:50 -0400 Date: Fri, 27 Oct 2017 22:11:53 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: X86 ML , "linux-kernel@vger.kernel.org" , Brian Gerst , Dave Hansen , Linus Torvalds Subject: Re: [PATCH 10/18] x86/asm/32: Pull MSR_IA32_SYSENTER_CS update code out of native_load_sp0() Message-ID: <20171027201153.GF12039@nazgul.tnic> References: <75b2372395f579c20ee6fd53d03eb79c6eea8e81.1509006199.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <75b2372395f579c20ee6fd53d03eb79c6eea8e81.1509006199.git.luto@kernel.org> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 26, 2017 at 01:26:42AM -0700, Andy Lutomirski wrote: > This causees the MSR_IA32_SYSENTER_CS write to move out of the Spellcheck pls. > paravirt hook. This shouldn't affect Xen PV: Xen already ignores > MSR_IA32_SYSENTER_ESP writes. In any event, Xen doesn't support > vm86() in a useful way. > > Note to any potential backporters: This patch won't break lguest, as > lguest didn't have any SYSENTER support at all. ... > diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c > index 11966251cd42..84d6c9f554d0 100644 > --- a/arch/x86/kernel/process_32.c > +++ b/arch/x86/kernel/process_32.c > @@ -287,6 +287,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) > * current_thread_info(). > */ > load_sp0(tss, next); > + refresh_sysenter_cs(next); /* in case prev or next is vm86 */ Ewww, side comments. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --