Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751864AbbGIKFn (ORCPT ); Thu, 9 Jul 2015 06:05:43 -0400 Received: from foss.arm.com ([217.140.101.70]:45253 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751499AbbGIKFh (ORCPT ); Thu, 9 Jul 2015 06:05:37 -0400 Message-ID: <559E476E.2000306@arm.com> Date: Thu, 09 Jul 2015 11:05:34 +0100 From: Marc Zyngier Organization: ARM Ltd User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.7.0 MIME-Version: 1.0 To: Mark Rutland CC: Catalin Marinas , Will Deacon , Christoffer Dall , "kvmarm@lists.cs.columbia.edu" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH 01/13] arm/arm64: Add new is_kernel_in_hyp_mode predicate References: <1436372356-30410-1-git-send-email-marc.zyngier@arm.com> <1436372356-30410-2-git-send-email-marc.zyngier@arm.com> <20150709094230.GA20105@leverpostej> In-Reply-To: <20150709094230.GA20105@leverpostej> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 871 Lines: 32 On 09/07/15 10:42, Mark Rutland wrote: > Hi, > >> +static inline bool is_kernel_in_hyp_mode(void) >> +{ >> + u64 el; >> + >> + asm("mrs %0, CurrentEL" : "=r" (el)); >> + return el == CurrentEL_EL2; >> +} > > If you can include cputype.h, I think this can be: > > static inline bool is_kernel_in_hyp_mode(void) > { > return read_cpuid(CurrentEL) == CurrentEL_EL2; > } This would indeed work, but CurrentEL is hardly an ID register. I feel slightly uncomfortable using read_cpuid (which might return a cached version at some point) for random system registers. Thoughts? M. -- Jazz is not dead. It just smells funny... -- 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/