From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935176AbcCQJUz (ORCPT ); Thu, 17 Mar 2016 05:20:55 -0400 Received: from terminus.zytor.com ([198.137.202.10]:39022 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933251AbcCQJUw (ORCPT ); Thu, 17 Mar 2016 05:20:52 -0400 Date: Thu, 17 Mar 2016 02:19:34 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: torvalds@linux-foundation.org, mingo@kernel.org, JBeulich@suse.com, david.vrabel@citrix.com, luto@kernel.org, tglx@linutronix.de, bp@alien8.de, luto@amacapital.net, hpa@zytor.com, boris.ostrovsky@oracle.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, brgerst@gmail.com, dvlasenk@redhat.com, peterz@infradead.org Reply-To: luto@amacapital.net, bp@alien8.de, hpa@zytor.com, boris.ostrovsky@oracle.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, brgerst@gmail.com, dvlasenk@redhat.com, peterz@infradead.org, torvalds@linux-foundation.org, mingo@kernel.org, david.vrabel@citrix.com, JBeulich@suse.com, luto@kernel.org, tglx@linutronix.de In-Reply-To: <8ce12013e6e4c0a44a97e316be4a6faff31bd5ea.1458162709.git.luto@kernel.org> References: <8ce12013e6e4c0a44a97e316be4a6faff31bd5ea.1458162709.git.luto@kernel.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/iopl: Fix iopl capability check on Xen PV Git-Commit-ID: c29016cf41fe9fa994a5ecca607cf5f1cd98801e X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: c29016cf41fe9fa994a5ecca607cf5f1cd98801e Gitweb: http://git.kernel.org/tip/c29016cf41fe9fa994a5ecca607cf5f1cd98801e Author: Andy Lutomirski AuthorDate: Wed, 16 Mar 2016 14:14:22 -0700 Committer: Ingo Molnar CommitDate: Thu, 17 Mar 2016 09:49:27 +0100 x86/iopl: Fix iopl capability check on Xen PV iopl(3) is supposed to work if iopl is already 3, even if unprivileged. This didn't work right on Xen PV. Fix it. Reviewewd-by: Jan Beulich Signed-off-by: Andy Lutomirski Cc: Andrew Cooper Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: David Vrabel Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jan Beulich Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/8ce12013e6e4c0a44a97e316be4a6faff31bd5ea.1458162709.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/ioport.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c index 37dae79..589b319 100644 --- a/arch/x86/kernel/ioport.c +++ b/arch/x86/kernel/ioport.c @@ -96,9 +96,14 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) SYSCALL_DEFINE1(iopl, unsigned int, level) { struct pt_regs *regs = current_pt_regs(); - unsigned int old = (regs->flags >> 12) & 3; struct thread_struct *t = ¤t->thread; + /* + * Careful: the IOPL bits in regs->flags are undefined under Xen PV + * and changing them has no effect. + */ + unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT; + if (level > 3) return -EINVAL; /* Trying to gain more privileges? */ @@ -106,8 +111,9 @@ SYSCALL_DEFINE1(iopl, unsigned int, level) if (!capable(CAP_SYS_RAWIO)) return -EPERM; } - regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); - t->iopl = level << 12; + regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | + (level << X86_EFLAGS_IOPL_BIT); + t->iopl = level << X86_EFLAGS_IOPL_BIT; set_iopl_mask(t->iopl); return 0;