From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E76CAC47096 for ; Thu, 3 Jun 2021 18:34:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFF40613D7 for ; Thu, 3 Jun 2021 18:34:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229955AbhFCSfs (ORCPT ); Thu, 3 Jun 2021 14:35:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:51224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229902AbhFCSfr (ORCPT ); Thu, 3 Jun 2021 14:35:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7F2C8613B8; Thu, 3 Jun 2021 18:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622745242; bh=osyrOd8rLcVCMiPHAeJKLzTGdMUBbbPPNLLfrYOVNtE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fOt+VKmNu2qb7NlmlC8F8f7NZks31mqaTKoFAcQTxTnnIZsP99bm4KVUW3Fy5BRvN k2jFjdJeC1Ex6aXIlzQTS6Z+2nmuqbXQ5BCBEDUFJ2hXtvBa2kF4PGG8m6Ug2xCo0Q 2mkPnUbq1g9fcBSTNR1e0d8gzL2CvA8qU1mdCLwmONsEdMYiX9MBJPQUtdKpSzTkEr ei3Ud1mbQSStGuUhg7+ec20zSiVnEUYt0Fyd7Ylz0JXyoDEzLq6C2N7S8fN7v4J9dy l0CBMMnNmYEK9oOkkz2xWN2Ub6RyqV+ey0y9/m+fBqIL12YAOOv7nPK2CygTSFZayc TwB4LD/lrL5yg== From: Will Deacon To: kvmarm@lists.cs.columbia.edu Cc: Will Deacon , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Mark Rutland , Christoffer Dall , Paolo Bonzini , Fuad Tabba , Quentin Perret , Sean Christopherson , David Brazdil , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/4] KVM: arm64: Extend comment in has_vhe() Date: Thu, 3 Jun 2021 19:33:45 +0100 Message-Id: <20210603183347.1695-3-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210603183347.1695-1-will@kernel.org> References: <20210603183347.1695-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org has_vhe() expands to a compile-time constant when evaluated from the VHE or nVHE code, alternatively checking a static key when called from elsewhere in the kernel. On face value, this looks like a case of premature optimization, but in fact this allows symbol references on VHE-specific code paths to be dropped from the nVHE object. Expand the comment in has_vhe() to make this clearer, hopefully discouraging anybody from simplifying the code. Cc: David Brazdil Signed-off-by: Will Deacon --- arch/arm64/include/asm/virt.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 7379f35ae2c6..3218ca17f819 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -111,6 +111,9 @@ static __always_inline bool has_vhe(void) /* * Code only run in VHE/NVHE hyp context can assume VHE is present or * absent. Otherwise fall back to caps. + * This allows the compiler to discard VHE-specific code from the + * nVHE object, reducing the number of external symbol references + * needed to link. */ if (is_vhe_hyp_code()) return true; -- 2.32.0.rc0.204.g9fa02ecfa5-goog